diff --git a/mini3d.c b/mini3d.c index 736d1fd..9ed3286 100644 --- a/mini3d.c +++ b/mini3d.c @@ -1,950 +1,950 @@ -//===================================================================== -// -// mini3d.c - Mini Software Render All-In-One -// -// build: -// mingw: gcc -O3 mini3d.c -o mini3d.exe -lgdi32 -// msvc: cl -O2 -nologo mini3d.c -// -// history: -// 2007.7.01 skywind create this file as a tutorial -// 2007.7.02 skywind implementate texture and color render -// 2008.3.15 skywind fixed a trapezoid issue -// 2015.8.09 skywind rewrite with more comment -// 2015.8.12 skywind adjust interfaces for clearity -// -//===================================================================== -#include -#include -#include -#include - -#include -#include - -typedef unsigned int IUINT32; - -//===================================================================== -// 数学库：此部分应该不用详解，熟悉 D3D 矩阵变换即可 -//===================================================================== -typedef struct { float m[4][4]; } matrix_t; -typedef struct { float x, y, z, w; } vector_t; -typedef vector_t point_t; - -int CMID(int x, int min, int max) { return (x < min)? min : ((x > max)? max : x); } - -// 计算插值：t 为 [0, 1] 之间的数值 -float interp(float x1, float x2, float t) { return x1 + (x2 - x1) * t; } - -// | v | -float vector_length(const vector_t *v) { - float sq = v->x * v->x + v->y * v->y + v->z * v->z; - return (float)sqrt(sq); -} - -// z = x + y -void vector_add(vector_t *z, const vector_t *x, const vector_t *y) { - z->x = x->x + y->x; - z->y = x->y + y->y; - z->z = x->z + y->z; - z->w = 1.0; -} - -// z = x - y -void vector_sub(vector_t *z, const vector_t *x, const vector_t *y) { - z->x = x->x - y->x; - z->y = x->y - y->y; - z->z = x->z - y->z; - z->w = 1.0; -} - -// 矢量点乘 -float vector_dotproduct(const vector_t *x, const vector_t *y) { - return x->x * y->x + x->y * y->y + x->z * y->z; -} - -// 矢量叉乘 -void vector_crossproduct(vector_t *z, const vector_t *x, const vector_t *y) { - float m1, m2, m3; - m1 = x->y * y->z - x->z * y->y; - m2 = x->z * y->x - x->x * y->z; - m3 = x->x * y->y - x->y * y->x; - z->x = m1; - z->y = m2; - z->z = m3; - z->w = 1.0f; -} - -// 矢量插值，t取值 [0, 1] -void vector_interp(vector_t *z, const vector_t *x1, const vector_t *x2, float t) { - z->x = interp(x1->x, x2->x, t); - z->y = interp(x1->y, x2->y, t); - z->z = interp(x1->z, x2->z, t); - z->w = 1.0f; -} - -// 矢量归一化 -void vector_normalize(vector_t *v) { - float length = vector_length(v); - if (length != 0.0f) { - float inv = 1.0f / length; - v->x *= inv; - v->y *= inv; - v->z *= inv; - } -} - -// c = a + b -void matrix_add(matrix_t *c, const matrix_t *a, const matrix_t *b) { - int i, j; - for (i = 0; i < 4; i++) { - for (j = 0; j < 4; j++) - c->m[i][j] = a->m[i][j] + b->m[i][j]; - } -} - -// c = a - b -void matrix_sub(matrix_t *c, const matrix_t *a, const matrix_t *b) { - int i, j; - for (i = 0; i < 4; i++) { - for (j = 0; j < 4; j++) - c->m[i][j] = a->m[i][j] - b->m[i][j]; - } -} - -// c = a * b -void matrix_mul(matrix_t *c, const matrix_t *a, const matrix_t *b) { - matrix_t z; - int i, j; - for (i = 0; i < 4; i++) { - for (j = 0; j < 4; j++) { - z.m[j][i] = (a->m[j][0] * b->m[0][i]) + - (a->m[j][1] * b->m[1][i]) + - (a->m[j][2] * b->m[2][i]) + - (a->m[j][3] * b->m[3][i]); - } - } - c[0] = z; -} - -// c = a * f -void matrix_scale(matrix_t *c, const matrix_t *a, float f) { - int i, j; - for (i = 0; i < 4; i++) { - for (j = 0; j < 4; j++) - c->m[i][j] = a->m[i][j] * f; - } -} - -// y = x * m -void matrix_apply(vector_t *y, const vector_t *x, const matrix_t *m) { - float X = x->x, Y = x->y, Z = x->z, W = x->w; - y->x = X * m->m[0][0] + Y * m->m[1][0] + Z * m->m[2][0] + W * m->m[3][0]; - y->y = X * m->m[0][1] + Y * m->m[1][1] + Z * m->m[2][1] + W * m->m[3][1]; - y->z = X * m->m[0][2] + Y * m->m[1][2] + Z * m->m[2][2] + W * m->m[3][2]; - y->w = X * m->m[0][3] + Y * m->m[1][3] + Z * m->m[2][3] + W * m->m[3][3]; -} - -void matrix_set_identity(matrix_t *m) { - m->m[0][0] = m->m[1][1] = m->m[2][2] = m->m[3][3] = 1.0f; - m->m[0][1] = m->m[0][2] = m->m[0][3] = 0.0f; - m->m[1][0] = m->m[1][2] = m->m[1][3] = 0.0f; - m->m[2][0] = m->m[2][1] = m->m[2][3] = 0.0f; - m->m[3][0] = m->m[3][1] = m->m[3][2] = 0.0f; -} - -void matrix_set_zero(matrix_t *m) { - m->m[0][0] = m->m[0][1] = m->m[0][2] = m->m[0][3] = 0.0f; - m->m[1][0] = m->m[1][1] = m->m[1][2] = m->m[1][3] = 0.0f; - m->m[2][0] = m->m[2][1] = m->m[2][2] = m->m[2][3] = 0.0f; - m->m[3][0] = m->m[3][1] = m->m[3][2] = m->m[3][3] = 0.0f; -} - -// 平移变换 -void matrix_set_translate(matrix_t *m, float x, float y, float z) { - matrix_set_identity(m); - m->m[3][0] = x; - m->m[3][1] = y; - m->m[3][2] = z; -} - -// 缩放变换 -void matrix_set_scale(matrix_t *m, float x, float y, float z) { - matrix_set_identity(m); - m->m[0][0] = x; - m->m[1][1] = y; - m->m[2][2] = z; -} - -// 旋转矩阵 -void matrix_set_rotate(matrix_t *m, float x, float y, float z, float theta) { - float qsin = (float)sin(theta * 0.5f); - float qcos = (float)cos(theta * 0.5f); - vector_t vec = { x, y, z, 1.0f }; - float w = qcos; - vector_normalize(&vec); - x = vec.x * qsin; - y = vec.y * qsin; - z = vec.z * qsin; - m->m[0][0] = 1 - 2 * y * y - 2 * z * z; - m->m[1][0] = 2 * x * y - 2 * w * z; - m->m[2][0] = 2 * x * z + 2 * w * y; - m->m[0][1] = 2 * x * y + 2 * w * z; - m->m[1][1] = 1 - 2 * x * x - 2 * z * z; - m->m[2][1] = 2 * y * z - 2 * w * x; - m->m[0][2] = 2 * x * z - 2 * w * y; - m->m[1][2] = 2 * y * z + 2 * w * x; - m->m[2][2] = 1 - 2 * x * x - 2 * y * y; - m->m[0][3] = m->m[1][3] = m->m[2][3] = 0.0f; - m->m[3][0] = m->m[3][1] = m->m[3][2] = 0.0f; - m->m[3][3] = 1.0f; -} - -// 设置摄像机 -void matrix_set_lookat(matrix_t *m, const vector_t *eye, const vector_t *at, const vector_t *up) { - vector_t xaxis, yaxis, zaxis; - - vector_sub(&zaxis, at, eye); - vector_normalize(&zaxis); - vector_crossproduct(&xaxis, up, &zaxis); - vector_normalize(&xaxis); - vector_crossproduct(&yaxis, &zaxis, &xaxis); - - m->m[0][0] = xaxis.x; - m->m[1][0] = xaxis.y; - m->m[2][0] = xaxis.z; - m->m[3][0] = -vector_dotproduct(&xaxis, eye); - - m->m[0][1] = yaxis.x; - m->m[1][1] = yaxis.y; - m->m[2][1] = yaxis.z; - m->m[3][1] = -vector_dotproduct(&yaxis, eye); - - m->m[0][2] = zaxis.x; - m->m[1][2] = zaxis.y; - m->m[2][2] = zaxis.z; - m->m[3][2] = -vector_dotproduct(&zaxis, eye); - - m->m[0][3] = m->m[1][3] = m->m[2][3] = 0.0f; - m->m[3][3] = 1.0f; -} - -// D3DXMatrixPerspectiveFovLH -void matrix_set_perspective(matrix_t *m, float fovy, float aspect, float zn, float zf) { - float fax = 1.0f / (float)tan(fovy * 0.5f); - matrix_set_zero(m); - m->m[0][0] = (float)(fax / aspect); - m->m[1][1] = (float)(fax); - m->m[2][2] = zf / (zf - zn); - m->m[3][2] = - zn * zf / (zf - zn); - m->m[2][3] = 1; -} - - -//===================================================================== -// 坐标变换 -//===================================================================== -typedef struct { - matrix_t world; // 世界坐标变换 - matrix_t view; // 摄影机坐标变换 - matrix_t projection; // 投影变换 - matrix_t transform; // transform = world * view * projection - float w, h; // 屏幕大小 -} transform_t; - - -// 矩阵更新，计算 transform = world * view * projection -void transform_update(transform_t *ts) { - matrix_t m; - matrix_mul(&m, &ts->world, &ts->view); - matrix_mul(&ts->transform, &m, &ts->projection); -} - -// 初始化，设置屏幕长宽 -void transform_init(transform_t *ts, int width, int height) { - float aspect = (float)width / ((float)height); - matrix_set_identity(&ts->world); - matrix_set_identity(&ts->view); - matrix_set_perspective(&ts->projection, 3.1415926f * 0.5f, aspect, 1.0f, 500.0f); - ts->w = (float)width; - ts->h = (float)height; - transform_update(ts); -} - -// 将矢量 x 进行 project -void transform_apply(const transform_t *ts, vector_t *y, const vector_t *x) { - matrix_apply(y, x, &ts->transform); -} - -// 检查齐次坐标同 cvv 的边界用于视锥裁剪 -int transform_check_cvv(const vector_t *v) { - float w = v->w; - int check = 0; - if (v->z < 0.0f) check |= 1; - if (v->z > w) check |= 2; - if (v->x < -w) check |= 4; - if (v->x > w) check |= 8; - if (v->y < -w) check |= 16; - if (v->y > w) check |= 32; - return check; -} - -// 归一化，得到屏幕坐标 -void transform_homogenize(const transform_t *ts, vector_t *y, const vector_t *x) { - float rhw = 1.0f / x->w; - y->x = (x->x * rhw + 1.0f) * ts->w * 0.5f; - y->y = (1.0f - x->y * rhw) * ts->h * 0.5f; - y->z = x->z * rhw; - y->w = 1.0f; -} - - -//===================================================================== -// 几何计算：顶点、扫描线、边缘、矩形、步长计算 -//===================================================================== -typedef struct { float r, g, b; } color_t; -typedef struct { float u, v; } texcoord_t; -typedef struct { point_t pos; texcoord_t tc; color_t color; float rhw; } vertex_t; - -typedef struct { vertex_t v, v1, v2; } edge_t; -typedef struct { float top, bottom; edge_t left, right; } trapezoid_t; -typedef struct { vertex_t v, step; int x, y, w; } scanline_t; - - -void vertex_rhw_init(vertex_t *v) { - float rhw = 1.0f / v->pos.w; - v->rhw = rhw; - v->tc.u *= rhw; - v->tc.v *= rhw; - v->color.r *= rhw; - v->color.g *= rhw; - v->color.b *= rhw; -} - -void vertex_interp(vertex_t *y, const vertex_t *x1, const vertex_t *x2, float t) { - vector_interp(&y->pos, &x1->pos, &x2->pos, t); - y->tc.u = interp(x1->tc.u, x2->tc.u, t); - y->tc.v = interp(x1->tc.v, x2->tc.v, t); - y->color.r = interp(x1->color.r, x2->color.r, t); - y->color.g = interp(x1->color.g, x2->color.g, t); - y->color.b = interp(x1->color.b, x2->color.b, t); - y->rhw = interp(x1->rhw, x2->rhw, t); -} - -void vertex_division(vertex_t *y, const vertex_t *x1, const vertex_t *x2, float w) { - float inv = 1.0f / w; - y->pos.x = (x2->pos.x - x1->pos.x) * inv; - y->pos.y = (x2->pos.y - x1->pos.y) * inv; - y->pos.z = (x2->pos.z - x1->pos.z) * inv; - y->pos.w = (x2->pos.w - x1->pos.w) * inv; - y->tc.u = (x2->tc.u - x1->tc.u) * inv; - y->tc.v = (x2->tc.v - x1->tc.v) * inv; - y->color.r = (x2->color.r - x1->color.r) * inv; - y->color.g = (x2->color.g - x1->color.g) * inv; - y->color.b = (x2->color.b - x1->color.b) * inv; - y->rhw = (x2->rhw - x1->rhw) * inv; -} - -void vertex_add(vertex_t *y, const vertex_t *x) { - y->pos.x += x->pos.x; - y->pos.y += x->pos.y; - y->pos.z += x->pos.z; - y->pos.w += x->pos.w; - y->rhw += x->rhw; - y->tc.u += x->tc.u; - y->tc.v += x->tc.v; - y->color.r += x->color.r; - y->color.g += x->color.g; - y->color.b += x->color.b; -} - -// 根据三角形生成 0-2 个梯形，并且返回合法梯形的数量 -int trapezoid_init_triangle(trapezoid_t *trap, const vertex_t *p1, - const vertex_t *p2, const vertex_t *p3) { - const vertex_t *p; - float k, x; - - if (p1->pos.y > p2->pos.y) p = p1, p1 = p2, p2 = p; - if (p1->pos.y > p3->pos.y) p = p1, p1 = p3, p3 = p; - if (p2->pos.y > p3->pos.y) p = p2, p2 = p3, p3 = p; - if (p1->pos.y == p2->pos.y && p1->pos.y == p3->pos.y) return 0; - if (p1->pos.x == p2->pos.x && p1->pos.x == p3->pos.x) return 0; - - if (p1->pos.y == p2->pos.y) { // triangle down - if (p1->pos.x > p2->pos.x) p = p1, p1 = p2, p2 = p; - trap[0].top = p1->pos.y; - trap[0].bottom = p3->pos.y; - trap[0].left.v1 = *p1; - trap[0].left.v2 = *p3; - trap[0].right.v1 = *p2; - trap[0].right.v2 = *p3; - return (trap[0].top < trap[0].bottom)? 1 : 0; - } - - if (p2->pos.y == p3->pos.y) { // triangle up - if (p2->pos.x > p3->pos.x) p = p2, p2 = p3, p3 = p; - trap[0].top = p1->pos.y; - trap[0].bottom = p3->pos.y; - trap[0].left.v1 = *p1; - trap[0].left.v2 = *p2; - trap[0].right.v1 = *p1; - trap[0].right.v2 = *p3; - return (trap[0].top < trap[0].bottom)? 1 : 0; - } - - trap[0].top = p1->pos.y; - trap[0].bottom = p2->pos.y; - trap[1].top = p2->pos.y; - trap[1].bottom = p3->pos.y; - - k = (p3->pos.y - p1->pos.y) / (p2->pos.y - p1->pos.y); - x = p1->pos.x + (p2->pos.x - p1->pos.x) * k; - - if (x <= p3->pos.x) { // triangle left - trap[0].left.v1 = *p1; - trap[0].left.v2 = *p2; - trap[0].right.v1 = *p1; - trap[0].right.v2 = *p3; - trap[1].left.v1 = *p2; - trap[1].left.v2 = *p3; - trap[1].right.v1 = *p1; - trap[1].right.v2 = *p3; - } else { // triangle right - trap[0].left.v1 = *p1; - trap[0].left.v2 = *p3; - trap[0].right.v1 = *p1; - trap[0].right.v2 = *p2; - trap[1].left.v1 = *p1; - trap[1].left.v2 = *p3; - trap[1].right.v1 = *p2; - trap[1].right.v2 = *p3; - } - - return 2; -} - -// 按照 Y 坐标计算出左右两条边纵坐标等于 Y 的顶点 -void trapezoid_edge_interp(trapezoid_t *trap, float y) { - float s1 = trap->left.v2.pos.y - trap->left.v1.pos.y; - float s2 = trap->right.v2.pos.y - trap->right.v1.pos.y; - float t1 = (y - trap->left.v1.pos.y) / s1; - float t2 = (y - trap->right.v1.pos.y) / s2; - vertex_interp(&trap->left.v, &trap->left.v1, &trap->left.v2, t1); - vertex_interp(&trap->right.v, &trap->right.v1, &trap->right.v2, t2); -} - -// 根据左右两边的端点，初始化计算出扫描线的起点和步长 -void trapezoid_init_scan_line(const trapezoid_t *trap, scanline_t *scanline, int y) { - float width = trap->right.v.pos.x - trap->left.v.pos.x; - scanline->x = (int)(trap->left.v.pos.x + 0.5f); - scanline->w = (int)(trap->right.v.pos.x + 0.5f) - scanline->x; - scanline->y = y; - scanline->v = trap->left.v; - if (trap->left.v.pos.x >= trap->right.v.pos.x) scanline->w = 0; - vertex_division(&scanline->step, &trap->left.v, &trap->right.v, width); -} - - -//===================================================================== -// 渲染设备 -//===================================================================== -typedef struct { - transform_t transform; // 坐标变换器 - int width; // 窗口宽度 - int height; // 窗口高度 - IUINT32 **framebuffer; // 像素缓存：framebuffer[y] 代表第 y行 - float **zbuffer; // 深度缓存：zbuffer[y] 为第 y行指针 - IUINT32 **texture; // 纹理：同样是每行索引 - int tex_width; // 纹理宽度 - int tex_height; // 纹理高度 - float max_u; // 纹理最大宽度：tex_width - 1 - float max_v; // 纹理最大高度：tex_height - 1 - int render_state; // 渲染状态 - IUINT32 background; // 背景颜色 - IUINT32 foreground; // 线框颜色 -} device_t; - -#define RENDER_STATE_WIREFRAME 1 // 渲染线框 -#define RENDER_STATE_TEXTURE 2 // 渲染纹理 -#define RENDER_STATE_COLOR 4 // 渲染颜色 - -// 设备初始化，fb为外部帧缓存，非 NULL 将引用外部帧缓存（每行 4字节对齐） -void device_init(device_t *device, int width, int height, void *fb) { - int need = sizeof(void*) * (height * 2 + 1024) + width * height * 8; - char *ptr = (char*)malloc(need + 64); - char *framebuf, *zbuf; - int j; - assert(ptr); - device->framebuffer = (IUINT32**)ptr; - device->zbuffer = (float**)(ptr + sizeof(void*) * height); - ptr += sizeof(void*) * height * 2; - device->texture = (IUINT32**)ptr; - ptr += sizeof(void*) * 1024; - framebuf = (char*)ptr; - zbuf = (char*)ptr + width * height * 4; - ptr += width * height * 8; - if (fb != NULL) framebuf = (char*)fb; - for (j = 0; j < height; j++) { - device->framebuffer[j] = (IUINT32*)(framebuf + width * 4 * j); - device->zbuffer[j] = (float*)(zbuf + width * 4 * j); - } - device->texture[0] = (IUINT32*)ptr; - device->texture[1] = (IUINT32*)(ptr + 16); - memset(device->texture[0], 0, 64); - device->tex_width = 2; - device->tex_height = 2; - device->max_u = 1.0f; - device->max_v = 1.0f; - device->width = width; - device->height = height; - device->background = 0xc0c0c0; - device->foreground = 0; - transform_init(&device->transform, width, height); - device->render_state = RENDER_STATE_WIREFRAME; -} - -// 删除设备 -void device_destroy(device_t *device) { - if (device->framebuffer) - free(device->framebuffer); - device->framebuffer = NULL; - device->zbuffer = NULL; - device->texture = NULL; -} - -// 设置当前纹理 -void device_set_texture(device_t *device, void *bits, long pitch, int w, int h) { - char *ptr = (char*)bits; - int j; - assert(w <= 1024 && h <= 1024); - for (j = 0; j < h; ptr += pitch, j++) // 重新计算每行纹理的指针 - device->texture[j] = (IUINT32*)ptr; - device->tex_width = w; - device->tex_height = h; - device->max_u = (float)(w - 1); - device->max_v = (float)(h - 1); -} - -// 清空 framebuffer 和 zbuffer -void device_clear(device_t *device, int mode) { - int y, x, height = device->height; - for (y = 0; y < device->height; y++) { - IUINT32 *dst = device->framebuffer[y]; - IUINT32 cc = (height - 1 - y) * 230 / (height - 1); - cc = (cc << 16) | (cc << 8) | cc; - if (mode == 0) cc = device->background; - for (x = device->width; x > 0; dst++, x--) dst[0] = cc; - } - for (y = 0; y < device->height; y++) { - float *dst = device->zbuffer[y]; - for (x = device->width; x > 0; dst++, x--) dst[0] = 0.0f; - } -} - -// 画点 -void device_pixel(device_t *device, int x, int y, IUINT32 color) { - if (((IUINT32)x) < (IUINT32)device->width && ((IUINT32)y) < (IUINT32)device->height) { - device->framebuffer[y][x] = color; - } -} - -// 绘制线段 -void device_draw_line(device_t *device, int x1, int y1, int x2, int y2, IUINT32 c) { - int x, y, rem = 0; - if (x1 == x2 && y1 == y2) { - device_pixel(device, x1, y1, c); - } else if (x1 == x2) { - int inc = (y1 <= y2)? 1 : -1; - for (y = y1; y != y2; y += inc) device_pixel(device, x1, y, c); - device_pixel(device, x2, y2, c); - } else if (y1 == y2) { - int inc = (x1 <= x2)? 1 : -1; - for (x = x1; x != x2; x += inc) device_pixel(device, x, y1, c); - device_pixel(device, x2, y2, c); - } else { - int dx = (x1 < x2)? x2 - x1 : x1 - x2; - int dy = (y1 < y2)? y2 - y1 : y1 - y2; - if (dx >= dy) { - if (x2 < x1) x = x1, y = y1, x1 = x2, y1 = y2, x2 = x, y2 = y; - for (x = x1, y = y1; x <= x2; x++) { - device_pixel(device, x, y, c); - rem += dy; - if (rem >= dx) { - rem -= dx; - y += (y2 >= y1)? 1 : -1; - device_pixel(device, x, y, c); - } - } - device_pixel(device, x2, y2, c); - } else { - if (y2 < y1) x = x1, y = y1, x1 = x2, y1 = y2, x2 = x, y2 = y; - for (x = x1, y = y1; y <= y2; y++) { - device_pixel(device, x, y, c); - rem += dx; - if (rem >= dy) { - rem -= dy; - x += (x2 >= x1)? 1 : -1; - device_pixel(device, x, y, c); - } - } - device_pixel(device, x2, y2, c); - } - } -} - -// 根据坐标读取纹理 -IUINT32 device_texture_read(const device_t *device, float u, float v) { - int x, y; - u = u * device->max_u; - v = v * device->max_v; - x = (int)(u + 0.5f); - y = (int)(v + 0.5f); - x = CMID(x, 0, device->tex_width - 1); - y = CMID(y, 0, device->tex_height - 1); - return device->texture[y][x]; -} - - -//===================================================================== -// 渲染实现 -//===================================================================== - -// 绘制扫描线 -void device_draw_scanline(device_t *device, scanline_t *scanline) { - IUINT32 *framebuffer = device->framebuffer[scanline->y]; - float *zbuffer = device->zbuffer[scanline->y]; - int x = scanline->x; - int w = scanline->w; - int width = device->width; - int render_state = device->render_state; - for (; w > 0; x++, w--) { - if (x >= 0 && x < width) { - float rhw = scanline->v.rhw; - if (rhw >= zbuffer[x]) { - float w = 1.0f / rhw; - zbuffer[x] = rhw; - if (render_state & RENDER_STATE_COLOR) { - float r = scanline->v.color.r * w; - float g = scanline->v.color.g * w; - float b = scanline->v.color.b * w; - int R = (int)(r * 255.0f); - int G = (int)(g * 255.0f); - int B = (int)(b * 255.0f); - R = CMID(R, 0, 255); - G = CMID(G, 0, 255); - B = CMID(B, 0, 255); - framebuffer[x] = (R << 16) | (G << 8) | (B); - } - if (render_state & RENDER_STATE_TEXTURE) { - float u = scanline->v.tc.u * w; - float v = scanline->v.tc.v * w; - IUINT32 cc = device_texture_read(device, u, v); - framebuffer[x] = cc; - } - } - } - vertex_add(&scanline->v, &scanline->step); - if (x >= width) break; - } -} - -// 主渲染函数 -void device_render_trap(device_t *device, trapezoid_t *trap) { - scanline_t scanline; - int j, top, bottom; - top = (int)(trap->top + 0.5f); - bottom = (int)(trap->bottom + 0.5f); - for (j = top; j < bottom; j++) { - if (j >= 0 && j < device->height) { - trapezoid_edge_interp(trap, (float)j + 0.5f); - trapezoid_init_scan_line(trap, &scanline, j); - device_draw_scanline(device, &scanline); - } - if (j >= device->height) break; - } -} - -// 根据 render_state 绘制原始三角形 -void device_draw_primitive(device_t *device, const vertex_t *v1, - const vertex_t *v2, const vertex_t *v3) { - point_t p1, p2, p3, c1, c2, c3; - int render_state = device->render_state; - - // 按照 Transform 变化 - transform_apply(&device->transform, &c1, &v1->pos); - transform_apply(&device->transform, &c2, &v2->pos); - transform_apply(&device->transform, &c3, &v3->pos); - - // 裁剪，注意此处可以完善为具体判断几个点在 cvv内以及同cvv相交平面的坐标比例 - // 进行进一步精细裁剪，将一个分解为几个完全处在 cvv内的三角形 - if (transform_check_cvv(&c1) != 0) return; - if (transform_check_cvv(&c2) != 0) return; - if (transform_check_cvv(&c3) != 0) return; - - // 归一化 - transform_homogenize(&device->transform, &p1, &c1); - transform_homogenize(&device->transform, &p2, &c2); - transform_homogenize(&device->transform, &p3, &c3); - - // 纹理或者色彩绘制 - if (render_state & (RENDER_STATE_TEXTURE | RENDER_STATE_COLOR)) { - vertex_t t1 = *v1, t2 = *v2, t3 = *v3; - trapezoid_t traps[2]; - int n; - - t1.pos = p1; - t2.pos = p2; - t3.pos = p3; - t1.pos.w = c1.w; - t2.pos.w = c2.w; - t3.pos.w = c3.w; - - vertex_rhw_init(&t1); // 初始化 w - vertex_rhw_init(&t2); // 初始化 w - vertex_rhw_init(&t3); // 初始化 w - - // 拆分三角形为0-2个梯形，并且返回可用梯形数量 - n = trapezoid_init_triangle(traps, &t1, &t2, &t3); - - if (n >= 1) device_render_trap(device, &traps[0]); - if (n >= 2) device_render_trap(device, &traps[1]); - } - - if (render_state & RENDER_STATE_WIREFRAME) { // 线框绘制 - device_draw_line(device, (int)p1.x, (int)p1.y, (int)p2.x, (int)p2.y, device->foreground); - device_draw_line(device, (int)p1.x, (int)p1.y, (int)p3.x, (int)p3.y, device->foreground); - device_draw_line(device, (int)p3.x, (int)p3.y, (int)p2.x, (int)p2.y, device->foreground); - } -} - - -//===================================================================== -// Win32 窗口及图形绘制：为 device 提供一个 DibSection 的 FB -//===================================================================== -int screen_w, screen_h, screen_exit = 0; -int screen_mx = 0, screen_my = 0, screen_mb = 0; -int screen_keys[512]; // 当前键盘按下状态 -static HWND screen_handle = NULL; // 主窗口 HWND -static HDC screen_dc = NULL; // 配套的 HDC -static HBITMAP screen_hb = NULL; // DIB -static HBITMAP screen_ob = NULL; // 老的 BITMAP -unsigned char *screen_fb = NULL; // frame buffer -long screen_pitch = 0; - -int screen_init(int w, int h, const TCHAR *title); // 屏幕初始化 -int screen_close(void); // 关闭屏幕 -void screen_dispatch(void); // 处理消息 -void screen_update(void); // 显示 FrameBuffer - -// win32 event handler -static LRESULT screen_events(HWND, UINT, WPARAM, LPARAM); - -#ifdef _MSC_VER -#pragma comment(lib, "gdi32.lib") -#pragma comment(lib, "user32.lib") -#endif - -// 初始化窗口并设置标题 -int screen_init(int w, int h, const TCHAR *title) { - WNDCLASS wc = { CS_BYTEALIGNCLIENT, (WNDPROC)screen_events, 0, 0, 0, - NULL, NULL, NULL, NULL, _T("SCREEN3.1415926") }; - BITMAPINFO bi = { { sizeof(BITMAPINFOHEADER), w, -h, 1, 32, BI_RGB, - w * h * 4, 0, 0, 0, 0 } }; - RECT rect = { 0, 0, w, h }; - int wx, wy, sx, sy; - LPVOID ptr; - HDC hDC; - - screen_close(); - - wc.hbrBackground = (HBRUSH)GetStockObject(BLACK_BRUSH); - wc.hInstance = GetModuleHandle(NULL); - wc.hCursor = LoadCursor(NULL, IDC_ARROW); - if (!RegisterClass(&wc)) return -1; - - screen_handle = CreateWindow(_T("SCREEN3.1415926"), title, - WS_OVERLAPPED | WS_CAPTION | WS_SYSMENU | WS_MINIMIZEBOX, - 0, 0, 0, 0, NULL, NULL, wc.hInstance, NULL); - if (screen_handle == NULL) return -2; - - screen_exit = 0; - hDC = GetDC(screen_handle); - screen_dc = CreateCompatibleDC(hDC); - ReleaseDC(screen_handle, hDC); - - screen_hb = CreateDIBSection(screen_dc, &bi, DIB_RGB_COLORS, &ptr, 0, 0); - if (screen_hb == NULL) return -3; - - screen_ob = (HBITMAP)SelectObject(screen_dc, screen_hb); - screen_fb = (unsigned char*)ptr; - screen_w = w; - screen_h = h; - screen_pitch = w * 4; - - AdjustWindowRect(&rect, GetWindowLong(screen_handle, GWL_STYLE), 0); - wx = rect.right - rect.left; - wy = rect.bottom - rect.top; - sx = (GetSystemMetrics(SM_CXSCREEN) - wx) / 2; - sy = (GetSystemMetrics(SM_CYSCREEN) - wy) / 2; - if (sy < 0) sy = 0; - SetWindowPos(screen_handle, NULL, sx, sy, wx, wy, (SWP_NOCOPYBITS | SWP_NOZORDER | SWP_SHOWWINDOW)); - SetForegroundWindow(screen_handle); - - ShowWindow(screen_handle, SW_NORMAL); - screen_dispatch(); - - memset(screen_keys, 0, sizeof(int) * 512); - memset(screen_fb, 0, w * h * 4); - - return 0; -} - -int screen_close(void) { - if (screen_dc) { - if (screen_ob) { - SelectObject(screen_dc, screen_ob); - screen_ob = NULL; - } - DeleteDC(screen_dc); - screen_dc = NULL; - } - if (screen_hb) { - DeleteObject(screen_hb); - screen_hb = NULL; - } - if (screen_handle) { - CloseWindow(screen_handle); - screen_handle = NULL; - } - return 0; -} - -static LRESULT screen_events(HWND hWnd, UINT msg, - WPARAM wParam, LPARAM lParam) { - switch (msg) { - case WM_CLOSE: screen_exit = 1; break; - case WM_KEYDOWN: screen_keys[wParam & 511] = 1; break; - case WM_KEYUP: screen_keys[wParam & 511] = 0; break; - default: return DefWindowProc(hWnd, msg, wParam, lParam); - } - return 0; -} - -void screen_dispatch(void) { - MSG msg; - while (1) { - if (!PeekMessage(&msg, NULL, 0, 0, PM_NOREMOVE)) break; - if (!GetMessage(&msg, NULL, 0, 0)) break; - DispatchMessage(&msg); - } -} - -void screen_update(void) { - HDC hDC = GetDC(screen_handle); - BitBlt(hDC, 0, 0, screen_w, screen_h, screen_dc, 0, 0, SRCCOPY); - ReleaseDC(screen_handle, hDC); - screen_dispatch(); -} - - -//===================================================================== -// 主程序 -//===================================================================== -vertex_t mesh[8] = { - { { -1, -1, 1, 1 }, { 0, 0 }, { 1.0f, 0.2f, 0.2f }, 1 }, - { { 1, -1, 1, 1 }, { 0, 1 }, { 0.2f, 1.0f, 0.2f }, 1 }, - { { 1, 1, 1, 1 }, { 1, 1 }, { 0.2f, 0.2f, 1.0f }, 1 }, - { { -1, 1, 1, 1 }, { 1, 0 }, { 1.0f, 0.2f, 1.0f }, 1 }, - { { -1, -1, -1, 1 }, { 0, 0 }, { 1.0f, 1.0f, 0.2f }, 1 }, - { { 1, -1, -1, 1 }, { 0, 1 }, { 0.2f, 1.0f, 1.0f }, 1 }, - { { 1, 1, -1, 1 }, { 1, 1 }, { 1.0f, 0.3f, 0.3f }, 1 }, - { { -1, 1, -1, 1 }, { 1, 0 }, { 0.2f, 1.0f, 0.3f }, 1 }, -}; - -void draw_plane(device_t *device, int a, int b, int c, int d) { - vertex_t p1 = mesh[a], p2 = mesh[b], p3 = mesh[c], p4 = mesh[d]; - p1.tc.u = 0, p1.tc.v = 0, p2.tc.u = 0, p2.tc.v = 1; - p3.tc.u = 1, p3.tc.v = 1, p4.tc.u = 1, p4.tc.v = 0; - device_draw_primitive(device, &p1, &p2, &p3); - device_draw_primitive(device, &p3, &p4, &p1); -} - -void draw_box(device_t *device, float theta) { - matrix_t m; - matrix_set_rotate(&m, -1, -0.5, 1, theta); - device->transform.world = m; - transform_update(&device->transform); - draw_plane(device, 0, 1, 2, 3); - draw_plane(device, 7, 6, 5, 4); - draw_plane(device, 0, 4, 5, 1); - draw_plane(device, 1, 5, 6, 2); - draw_plane(device, 2, 6, 7, 3); - draw_plane(device, 3, 7, 4, 0); -} - -void camera_at_zero(device_t *device, float x, float y, float z) { - point_t eye = { x, y, z, 1 }, at = { 0, 0, 0, 1 }, up = { 0, 0, 1, 1 }; - matrix_set_lookat(&device->transform.view, &eye, &at, &up); - transform_update(&device->transform); -} - -void init_texture(device_t *device) { - static IUINT32 texture[256][256]; - int i, j; - for (j = 0; j < 256; j++) { - for (i = 0; i < 256; i++) { - int x = i / 32, y = j / 32; - texture[j][i] = ((x + y) & 1)? 0xffffff : 0x3fbcef; - } - } - device_set_texture(device, texture, 256 * 4, 256, 256); -} - -int main(void) -{ - device_t device; - int states[] = { RENDER_STATE_TEXTURE, RENDER_STATE_COLOR, RENDER_STATE_WIREFRAME }; - int indicator = 0; - int kbhit = 0; - float alpha = 1; - float pos = 3.5; - - TCHAR *title = _T("Mini3d (software render tutorial) - ") - _T("Left/Right: rotation, Up/Down: forward/backward, Space: switch state"); - - if (screen_init(800, 600, title)) - return -1; - - device_init(&device, 800, 600, screen_fb); - camera_at_zero(&device, 3, 0, 0); - - init_texture(&device); - device.render_state = RENDER_STATE_TEXTURE; - - while (screen_exit == 0 && screen_keys[VK_ESCAPE] == 0) { - screen_dispatch(); - device_clear(&device, 1); - camera_at_zero(&device, pos, 0, 0); - - if (screen_keys[VK_UP]) pos -= 0.01f; - if (screen_keys[VK_DOWN]) pos += 0.01f; - if (screen_keys[VK_LEFT]) alpha += 0.01f; - if (screen_keys[VK_RIGHT]) alpha -= 0.01f; - - if (screen_keys[VK_SPACE]) { - if (kbhit == 0) { - kbhit = 1; - if (++indicator >= 3) indicator = 0; - device.render_state = states[indicator]; - } - } else { - kbhit = 0; - } - - draw_box(&device, alpha); - screen_update(); - Sleep(1); - } - return 0; -} - +//===================================================================== +// +// mini3d.c - Mini Software Render All-In-One +// +// build: +// mingw: gcc -O3 mini3d.c -o mini3d.exe -lgdi32 +// msvc: cl -O2 -nologo mini3d.c +// +// history: +// 2007.7.01 skywind create this file as a tutorial +// 2007.7.02 skywind implementate texture and color render +// 2008.3.15 skywind fixed a trapezoid issue +// 2015.8.09 skywind rewrite with more comment +// 2015.8.12 skywind adjust interfaces for clarity +// +//===================================================================== +#include +#include +#include +#include + +#include +#include + +typedef unsigned int IUINT32; + +//===================================================================== +// 数学库：此部分应该不用详解，熟悉 D3D 矩阵变换即可 +//===================================================================== +typedef struct { float m[4][4]; } matrix_t; +typedef struct { float x, y, z, w; } vector_t; +typedef vector_t point_t; + +int CMID(int x, int min, int max) { return (x < min)? min : ((x > max)? max : x); } + +// 计算插值：t 为 [0, 1] 之间的数值 +float interp(float x1, float x2, float t) { return x1 + (x2 - x1) * t; } + +// | v | +float vector_length(const vector_t *v) { + float sq = v->x * v->x + v->y * v->y + v->z * v->z; + return (float)sqrt(sq); +} + +// z = x + y +void vector_add(vector_t *z, const vector_t *x, const vector_t *y) { + z->x = x->x + y->x; + z->y = x->y + y->y; + z->z = x->z + y->z; + z->w = 1.0; +} + +// z = x - y +void vector_sub(vector_t *z, const vector_t *x, const vector_t *y) { + z->x = x->x - y->x; + z->y = x->y - y->y; + z->z = x->z - y->z; + z->w = 1.0; +} + +// 矢量点乘 +float vector_dotproduct(const vector_t *x, const vector_t *y) { + return x->x * y->x + x->y * y->y + x->z * y->z; +} + +// 矢量叉乘 +void vector_crossproduct(vector_t *z, const vector_t *x, const vector_t *y) { + float m1, m2, m3; + m1 = x->y * y->z - x->z * y->y; + m2 = x->z * y->x - x->x * y->z; + m3 = x->x * y->y - x->y * y->x; + z->x = m1; + z->y = m2; + z->z = m3; + z->w = 1.0f; +} + +// 矢量插值，t取值 [0, 1] +void vector_interp(vector_t *z, const vector_t *x1, const vector_t *x2, float t) { + z->x = interp(x1->x, x2->x, t); + z->y = interp(x1->y, x2->y, t); + z->z = interp(x1->z, x2->z, t); + z->w = 1.0f; +} + +// 矢量归一化 +void vector_normalize(vector_t *v) { + float length = vector_length(v); + if (length != 0.0f) { + float inv = 1.0f / length; + v->x *= inv; + v->y *= inv; + v->z *= inv; + } +} + +// c = a + b +void matrix_add(matrix_t *c, const matrix_t *a, const matrix_t *b) { + int i, j; + for (i = 0; i < 4; i++) { + for (j = 0; j < 4; j++) + c->m[i][j] = a->m[i][j] + b->m[i][j]; + } +} + +// c = a - b +void matrix_sub(matrix_t *c, const matrix_t *a, const matrix_t *b) { + int i, j; + for (i = 0; i < 4; i++) { + for (j = 0; j < 4; j++) + c->m[i][j] = a->m[i][j] - b->m[i][j]; + } +} + +// c = a * b +void matrix_mul(matrix_t *c, const matrix_t *a, const matrix_t *b) { + matrix_t z; + int i, j; + for (i = 0; i < 4; i++) { + for (j = 0; j < 4; j++) { + z.m[j][i] = (a->m[j][0] * b->m[0][i]) + + (a->m[j][1] * b->m[1][i]) + + (a->m[j][2] * b->m[2][i]) + + (a->m[j][3] * b->m[3][i]); + } + } + c[0] = z; +} + +// c = a * f +void matrix_scale(matrix_t *c, const matrix_t *a, float f) { + int i, j; + for (i = 0; i < 4; i++) { + for (j = 0; j < 4; j++) + c->m[i][j] = a->m[i][j] * f; + } +} + +// y = x * m +void matrix_apply(vector_t *y, const vector_t *x, const matrix_t *m) { + float X = x->x, Y = x->y, Z = x->z, W = x->w; + y->x = X * m->m[0][0] + Y * m->m[1][0] + Z * m->m[2][0] + W * m->m[3][0]; + y->y = X * m->m[0][1] + Y * m->m[1][1] + Z * m->m[2][1] + W * m->m[3][1]; + y->z = X * m->m[0][2] + Y * m->m[1][2] + Z * m->m[2][2] + W * m->m[3][2]; + y->w = X * m->m[0][3] + Y * m->m[1][3] + Z * m->m[2][3] + W * m->m[3][3]; +} + +void matrix_set_identity(matrix_t *m) { + m->m[0][0] = m->m[1][1] = m->m[2][2] = m->m[3][3] = 1.0f; + m->m[0][1] = m->m[0][2] = m->m[0][3] = 0.0f; + m->m[1][0] = m->m[1][2] = m->m[1][3] = 0.0f; + m->m[2][0] = m->m[2][1] = m->m[2][3] = 0.0f; + m->m[3][0] = m->m[3][1] = m->m[3][2] = 0.0f; +} + +void matrix_set_zero(matrix_t *m) { + m->m[0][0] = m->m[0][1] = m->m[0][2] = m->m[0][3] = 0.0f; + m->m[1][0] = m->m[1][1] = m->m[1][2] = m->m[1][3] = 0.0f; + m->m[2][0] = m->m[2][1] = m->m[2][2] = m->m[2][3] = 0.0f; + m->m[3][0] = m->m[3][1] = m->m[3][2] = m->m[3][3] = 0.0f; +} + +// 平移变换 +void matrix_set_translate(matrix_t *m, float x, float y, float z) { + matrix_set_identity(m); + m->m[3][0] = x; + m->m[3][1] = y; + m->m[3][2] = z; +} + +// 缩放变换 +void matrix_set_scale(matrix_t *m, float x, float y, float z) { + matrix_set_identity(m); + m->m[0][0] = x; + m->m[1][1] = y; + m->m[2][2] = z; +} + +// 旋转矩阵 +void matrix_set_rotate(matrix_t *m, float x, float y, float z, float theta) { + float qsin = (float)sin(theta * 0.5f); + float qcos = (float)cos(theta * 0.5f); + vector_t vec = { x, y, z, 1.0f }; + float w = qcos; + vector_normalize(&vec); + x = vec.x * qsin; + y = vec.y * qsin; + z = vec.z * qsin; + m->m[0][0] = 1 - 2 * y * y - 2 * z * z; + m->m[1][0] = 2 * x * y - 2 * w * z; + m->m[2][0] = 2 * x * z + 2 * w * y; + m->m[0][1] = 2 * x * y + 2 * w * z; + m->m[1][1] = 1 - 2 * x * x - 2 * z * z; + m->m[2][1] = 2 * y * z - 2 * w * x; + m->m[0][2] = 2 * x * z - 2 * w * y; + m->m[1][2] = 2 * y * z + 2 * w * x; + m->m[2][2] = 1 - 2 * x * x - 2 * y * y; + m->m[0][3] = m->m[1][3] = m->m[2][3] = 0.0f; + m->m[3][0] = m->m[3][1] = m->m[3][2] = 0.0f; + m->m[3][3] = 1.0f; +} + +// 设置摄像机 +void matrix_set_lookat(matrix_t *m, const vector_t *eye, const vector_t *at, const vector_t *up) { + vector_t xaxis, yaxis, zaxis; + + vector_sub(&zaxis, at, eye); + vector_normalize(&zaxis); + vector_crossproduct(&xaxis, up, &zaxis); + vector_normalize(&xaxis); + vector_crossproduct(&yaxis, &zaxis, &xaxis); + + m->m[0][0] = xaxis.x; + m->m[1][0] = xaxis.y; + m->m[2][0] = xaxis.z; + m->m[3][0] = -vector_dotproduct(&xaxis, eye); + + m->m[0][1] = yaxis.x; + m->m[1][1] = yaxis.y; + m->m[2][1] = yaxis.z; + m->m[3][1] = -vector_dotproduct(&yaxis, eye); + + m->m[0][2] = zaxis.x; + m->m[1][2] = zaxis.y; + m->m[2][2] = zaxis.z; + m->m[3][2] = -vector_dotproduct(&zaxis, eye); + + m->m[0][3] = m->m[1][3] = m->m[2][3] = 0.0f; + m->m[3][3] = 1.0f; +} + +// D3DXMatrixPerspectiveFovLH +void matrix_set_perspective(matrix_t *m, float fovy, float aspect, float zn, float zf) { + float fax = 1.0f / (float)tan(fovy * 0.5f); + matrix_set_zero(m); + m->m[0][0] = (float)(fax / aspect); + m->m[1][1] = (float)(fax); + m->m[2][2] = zf / (zf - zn); + m->m[3][2] = - zn * zf / (zf - zn); + m->m[2][3] = 1; +} + + +//===================================================================== +// 坐标变换 +//===================================================================== +typedef struct { + matrix_t world; // 世界坐标变换 + matrix_t view; // 摄影机坐标变换 + matrix_t projection; // 投影变换 + matrix_t transform; // transform = world * view * projection + float w, h; // 屏幕大小 +} transform_t; + + +// 矩阵更新，计算 transform = world * view * projection +void transform_update(transform_t *ts) { + matrix_t m; + matrix_mul(&m, &ts->world, &ts->view); + matrix_mul(&ts->transform, &m, &ts->projection); +} + +// 初始化，设置屏幕长宽 +void transform_init(transform_t *ts, int width, int height) { + float aspect = (float)width / ((float)height); + matrix_set_identity(&ts->world); + matrix_set_identity(&ts->view); + matrix_set_perspective(&ts->projection, 3.1415926f * 0.5f, aspect, 1.0f, 500.0f); + ts->w = (float)width; + ts->h = (float)height; + transform_update(ts); +} + +// 将矢量 x 进行 project +void transform_apply(const transform_t *ts, vector_t *y, const vector_t *x) { + matrix_apply(y, x, &ts->transform); +} + +// 检查齐次坐标同 cvv 的边界用于视锥裁剪 +int transform_check_cvv(const vector_t *v) { + float w = v->w; + int check = 0; + if (v->z < 0.0f) check |= 1; + if (v->z > w) check |= 2; + if (v->x < -w) check |= 4; + if (v->x > w) check |= 8; + if (v->y < -w) check |= 16; + if (v->y > w) check |= 32; + return check; +} + +// 归一化，得到屏幕坐标 +void transform_homogenize(const transform_t *ts, vector_t *y, const vector_t *x) { + float rhw = 1.0f / x->w; + y->x = (x->x * rhw + 1.0f) * ts->w * 0.5f; + y->y = (1.0f - x->y * rhw) * ts->h * 0.5f; + y->z = x->z * rhw; + y->w = 1.0f; +} + + +//===================================================================== +// 几何计算：顶点、扫描线、边缘、矩形、步长计算 +//===================================================================== +typedef struct { float r, g, b; } color_t; +typedef struct { float u, v; } texcoord_t; +typedef struct { point_t pos; texcoord_t tc; color_t color; float rhw; } vertex_t; + +typedef struct { vertex_t v, v1, v2; } edge_t; +typedef struct { float top, bottom; edge_t left, right; } trapezoid_t; +typedef struct { vertex_t v, step; int x, y, w; } scanline_t; + + +void vertex_rhw_init(vertex_t *v) { + float rhw = 1.0f / v->pos.w; + v->rhw = rhw; + v->tc.u *= rhw; + v->tc.v *= rhw; + v->color.r *= rhw; + v->color.g *= rhw; + v->color.b *= rhw; +} + +void vertex_interp(vertex_t *y, const vertex_t *x1, const vertex_t *x2, float t) { + vector_interp(&y->pos, &x1->pos, &x2->pos, t); + y->tc.u = interp(x1->tc.u, x2->tc.u, t); + y->tc.v = interp(x1->tc.v, x2->tc.v, t); + y->color.r = interp(x1->color.r, x2->color.r, t); + y->color.g = interp(x1->color.g, x2->color.g, t); + y->color.b = interp(x1->color.b, x2->color.b, t); + y->rhw = interp(x1->rhw, x2->rhw, t); +} + +void vertex_division(vertex_t *y, const vertex_t *x1, const vertex_t *x2, float w) { + float inv = 1.0f / w; + y->pos.x = (x2->pos.x - x1->pos.x) * inv; + y->pos.y = (x2->pos.y - x1->pos.y) * inv; + y->pos.z = (x2->pos.z - x1->pos.z) * inv; + y->pos.w = (x2->pos.w - x1->pos.w) * inv; + y->tc.u = (x2->tc.u - x1->tc.u) * inv; + y->tc.v = (x2->tc.v - x1->tc.v) * inv; + y->color.r = (x2->color.r - x1->color.r) * inv; + y->color.g = (x2->color.g - x1->color.g) * inv; + y->color.b = (x2->color.b - x1->color.b) * inv; + y->rhw = (x2->rhw - x1->rhw) * inv; +} + +void vertex_add(vertex_t *y, const vertex_t *x) { + y->pos.x += x->pos.x; + y->pos.y += x->pos.y; + y->pos.z += x->pos.z; + y->pos.w += x->pos.w; + y->rhw += x->rhw; + y->tc.u += x->tc.u; + y->tc.v += x->tc.v; + y->color.r += x->color.r; + y->color.g += x->color.g; + y->color.b += x->color.b; +} + +// 根据三角形生成 0-2 个梯形，并且返回合法梯形的数量 +int trapezoid_init_triangle(trapezoid_t *trap, const vertex_t *p1, + const vertex_t *p2, const vertex_t *p3) { + const vertex_t *p; + float k, x; + + if (p1->pos.y > p2->pos.y) p = p1, p1 = p2, p2 = p; + if (p1->pos.y > p3->pos.y) p = p1, p1 = p3, p3 = p; + if (p2->pos.y > p3->pos.y) p = p2, p2 = p3, p3 = p; + if (p1->pos.y == p2->pos.y && p1->pos.y == p3->pos.y) return 0; + if (p1->pos.x == p2->pos.x && p1->pos.x == p3->pos.x) return 0; + + if (p1->pos.y == p2->pos.y) { // triangle down + if (p1->pos.x > p2->pos.x) p = p1, p1 = p2, p2 = p; + trap[0].top = p1->pos.y; + trap[0].bottom = p3->pos.y; + trap[0].left.v1 = *p1; + trap[0].left.v2 = *p3; + trap[0].right.v1 = *p2; + trap[0].right.v2 = *p3; + return (trap[0].top < trap[0].bottom)? 1 : 0; + } + + if (p2->pos.y == p3->pos.y) { // triangle up + if (p2->pos.x > p3->pos.x) p = p2, p2 = p3, p3 = p; + trap[0].top = p1->pos.y; + trap[0].bottom = p3->pos.y; + trap[0].left.v1 = *p1; + trap[0].left.v2 = *p2; + trap[0].right.v1 = *p1; + trap[0].right.v2 = *p3; + return (trap[0].top < trap[0].bottom)? 1 : 0; + } + + trap[0].top = p1->pos.y; + trap[0].bottom = p2->pos.y; + trap[1].top = p2->pos.y; + trap[1].bottom = p3->pos.y; + + k = (p3->pos.y - p1->pos.y) / (p2->pos.y - p1->pos.y); + x = p1->pos.x + (p2->pos.x - p1->pos.x) * k; + + if (x <= p3->pos.x) { // triangle left + trap[0].left.v1 = *p1; + trap[0].left.v2 = *p2; + trap[0].right.v1 = *p1; + trap[0].right.v2 = *p3; + trap[1].left.v1 = *p2; + trap[1].left.v2 = *p3; + trap[1].right.v1 = *p1; + trap[1].right.v2 = *p3; + } else { // triangle right + trap[0].left.v1 = *p1; + trap[0].left.v2 = *p3; + trap[0].right.v1 = *p1; + trap[0].right.v2 = *p2; + trap[1].left.v1 = *p1; + trap[1].left.v2 = *p3; + trap[1].right.v1 = *p2; + trap[1].right.v2 = *p3; + } + + return 2; +} + +// 按照 Y 坐标计算出左右两条边纵坐标等于 Y 的顶点 +void trapezoid_edge_interp(trapezoid_t *trap, float y) { + float s1 = trap->left.v2.pos.y - trap->left.v1.pos.y; + float s2 = trap->right.v2.pos.y - trap->right.v1.pos.y; + float t1 = (y - trap->left.v1.pos.y) / s1; + float t2 = (y - trap->right.v1.pos.y) / s2; + vertex_interp(&trap->left.v, &trap->left.v1, &trap->left.v2, t1); + vertex_interp(&trap->right.v, &trap->right.v1, &trap->right.v2, t2); +} + +// 根据左右两边的端点，初始化计算出扫描线的起点和步长 +void trapezoid_init_scan_line(const trapezoid_t *trap, scanline_t *scanline, int y) { + float width = trap->right.v.pos.x - trap->left.v.pos.x; + scanline->x = (int)(trap->left.v.pos.x + 0.5f); + scanline->w = (int)(trap->right.v.pos.x + 0.5f) - scanline->x; + scanline->y = y; + scanline->v = trap->left.v; + if (trap->left.v.pos.x >= trap->right.v.pos.x) scanline->w = 0; + vertex_division(&scanline->step, &trap->left.v, &trap->right.v, width); +} + + +//===================================================================== +// 渲染设备 +//===================================================================== +typedef struct { + transform_t transform; // 坐标变换器 + int width; // 窗口宽度 + int height; // 窗口高度 + IUINT32 **framebuffer; // 像素缓存：framebuffer[y] 代表第 y行 + float **zbuffer; // 深度缓存：zbuffer[y] 为第 y行指针 + IUINT32 **texture; // 纹理：同样是每行索引 + int tex_width; // 纹理宽度 + int tex_height; // 纹理高度 + float max_u; // 纹理最大宽度：tex_width - 1 + float max_v; // 纹理最大高度：tex_height - 1 + int render_state; // 渲染状态 + IUINT32 background; // 背景颜色 + IUINT32 foreground; // 线框颜色 +} device_t; + +#define RENDER_STATE_WIREFRAME 1 // 渲染线框 +#define RENDER_STATE_TEXTURE 2 // 渲染纹理 +#define RENDER_STATE_COLOR 4 // 渲染颜色 + +// 设备初始化，fb为外部帧缓存，非 NULL 将引用外部帧缓存（每行 4字节对齐） +void device_init(device_t *device, int width, int height, void *fb) { + int need = sizeof(void*) * (height * 2 + 1024) + width * height * 8; + char *ptr = (char*)malloc(need + 64); + char *framebuf, *zbuf; + int j; + assert(ptr); + device->framebuffer = (IUINT32**)ptr; + device->zbuffer = (float**)(ptr + sizeof(void*) * height); + ptr += sizeof(void*) * height * 2; + device->texture = (IUINT32**)ptr; + ptr += sizeof(void*) * 1024; + framebuf = (char*)ptr; + zbuf = (char*)ptr + width * height * 4; + ptr += width * height * 8; + if (fb != NULL) framebuf = (char*)fb; + for (j = 0; j < height; j++) { + device->framebuffer[j] = (IUINT32*)(framebuf + width * 4 * j); + device->zbuffer[j] = (float*)(zbuf + width * 4 * j); + } + device->texture[0] = (IUINT32*)ptr; + device->texture[1] = (IUINT32*)(ptr + 16); + memset(device->texture[0], 0, 64); + device->tex_width = 2; + device->tex_height = 2; + device->max_u = 1.0f; + device->max_v = 1.0f; + device->width = width; + device->height = height; + device->background = 0xc0c0c0; + device->foreground = 0; + transform_init(&device->transform, width, height); + device->render_state = RENDER_STATE_WIREFRAME; +} + +// 删除设备 +void device_destroy(device_t *device) { + if (device->framebuffer) + free(device->framebuffer); + device->framebuffer = NULL; + device->zbuffer = NULL; + device->texture = NULL; +} + +// 设置当前纹理 +void device_set_texture(device_t *device, void *bits, long pitch, int w, int h) { + char *ptr = (char*)bits; + int j; + assert(w <= 1024 && h <= 1024); + for (j = 0; j < h; ptr += pitch, j++) // 重新计算每行纹理的指针 + device->texture[j] = (IUINT32*)ptr; + device->tex_width = w; + device->tex_height = h; + device->max_u = (float)(w - 1); + device->max_v = (float)(h - 1); +} + +// 清空 framebuffer 和 zbuffer +void device_clear(device_t *device, int mode) { + int y, x, height = device->height; + for (y = 0; y < device->height; y++) { + IUINT32 *dst = device->framebuffer[y]; + IUINT32 cc = (height - 1 - y) * 230 / (height - 1); + cc = (cc << 16) | (cc << 8) | cc; + if (mode == 0) cc = device->background; + for (x = device->width; x > 0; dst++, x--) dst[0] = cc; + } + for (y = 0; y < device->height; y++) { + float *dst = device->zbuffer[y]; + for (x = device->width; x > 0; dst++, x--) dst[0] = 0.0f; + } +} + +// 画点 +void device_pixel(device_t *device, int x, int y, IUINT32 color) { + if (((IUINT32)x) < (IUINT32)device->width && ((IUINT32)y) < (IUINT32)device->height) { + device->framebuffer[y][x] = color; + } +} + +// 绘制线段 +void device_draw_line(device_t *device, int x1, int y1, int x2, int y2, IUINT32 c) { + int x, y, rem = 0; + if (x1 == x2 && y1 == y2) { + device_pixel(device, x1, y1, c); + } else if (x1 == x2) { + int inc = (y1 <= y2)? 1 : -1; + for (y = y1; y != y2; y += inc) device_pixel(device, x1, y, c); + device_pixel(device, x2, y2, c); + } else if (y1 == y2) { + int inc = (x1 <= x2)? 1 : -1; + for (x = x1; x != x2; x += inc) device_pixel(device, x, y1, c); + device_pixel(device, x2, y2, c); + } else { + int dx = (x1 < x2)? x2 - x1 : x1 - x2; + int dy = (y1 < y2)? y2 - y1 : y1 - y2; + if (dx >= dy) { + if (x2 < x1) x = x1, y = y1, x1 = x2, y1 = y2, x2 = x, y2 = y; + for (x = x1, y = y1; x <= x2; x++) { + device_pixel(device, x, y, c); + rem += dy; + if (rem >= dx) { + rem -= dx; + y += (y2 >= y1)? 1 : -1; + device_pixel(device, x, y, c); + } + } + device_pixel(device, x2, y2, c); + } else { + if (y2 < y1) x = x1, y = y1, x1 = x2, y1 = y2, x2 = x, y2 = y; + for (x = x1, y = y1; y <= y2; y++) { + device_pixel(device, x, y, c); + rem += dx; + if (rem >= dy) { + rem -= dy; + x += (x2 >= x1)? 1 : -1; + device_pixel(device, x, y, c); + } + } + device_pixel(device, x2, y2, c); + } + } +} + +// 根据坐标读取纹理 +IUINT32 device_texture_read(const device_t *device, float u, float v) { + int x, y; + u = u * device->max_u; + v = v * device->max_v; + x = (int)(u + 0.5f); + y = (int)(v + 0.5f); + x = CMID(x, 0, device->tex_width - 1); + y = CMID(y, 0, device->tex_height - 1); + return device->texture[y][x]; +} + + +//===================================================================== +// 渲染实现 +//===================================================================== + +// 绘制扫描线 +void device_draw_scanline(device_t *device, scanline_t *scanline) { + IUINT32 *framebuffer = device->framebuffer[scanline->y]; + float *zbuffer = device->zbuffer[scanline->y]; + int x = scanline->x; + int w = scanline->w; + int width = device->width; + int render_state = device->render_state; + for (; w > 0; x++, w--) { + if (x >= 0 && x < width) { + float rhw = scanline->v.rhw; + if (rhw >= zbuffer[x]) { + float w = 1.0f / rhw; + zbuffer[x] = rhw; + if (render_state & RENDER_STATE_COLOR) { + float r = scanline->v.color.r * w; + float g = scanline->v.color.g * w; + float b = scanline->v.color.b * w; + int R = (int)(r * 255.0f); + int G = (int)(g * 255.0f); + int B = (int)(b * 255.0f); + R = CMID(R, 0, 255); + G = CMID(G, 0, 255); + B = CMID(B, 0, 255); + framebuffer[x] = (R << 16) | (G << 8) | (B); + } + if (render_state & RENDER_STATE_TEXTURE) { + float u = scanline->v.tc.u * w; + float v = scanline->v.tc.v * w; + IUINT32 cc = device_texture_read(device, u, v); + framebuffer[x] = cc; + } + } + } + vertex_add(&scanline->v, &scanline->step); + if (x >= width) break; + } +} + +// 主渲染函数 +void device_render_trap(device_t *device, trapezoid_t *trap) { + scanline_t scanline; + int j, top, bottom; + top = (int)(trap->top + 0.5f); + bottom = (int)(trap->bottom + 0.5f); + for (j = top; j < bottom; j++) { + if (j >= 0 && j < device->height) { + trapezoid_edge_interp(trap, (float)j + 0.5f); + trapezoid_init_scan_line(trap, &scanline, j); + device_draw_scanline(device, &scanline); + } + if (j >= device->height) break; + } +} + +// 根据 render_state 绘制原始三角形 +void device_draw_primitive(device_t *device, const vertex_t *v1, + const vertex_t *v2, const vertex_t *v3) { + point_t p1, p2, p3, c1, c2, c3; + int render_state = device->render_state; + + // 按照 Transform 变化 + transform_apply(&device->transform, &c1, &v1->pos); + transform_apply(&device->transform, &c2, &v2->pos); + transform_apply(&device->transform, &c3, &v3->pos); + + // 裁剪，注意此处可以完善为具体判断几个点在 cvv内以及同cvv相交平面的坐标比例 + // 进行进一步精细裁剪，将一个分解为几个完全处在 cvv内的三角形 + if (transform_check_cvv(&c1) != 0) return; + if (transform_check_cvv(&c2) != 0) return; + if (transform_check_cvv(&c3) != 0) return; + + // 归一化 + transform_homogenize(&device->transform, &p1, &c1); + transform_homogenize(&device->transform, &p2, &c2); + transform_homogenize(&device->transform, &p3, &c3); + + // 纹理或者色彩绘制 + if (render_state & (RENDER_STATE_TEXTURE | RENDER_STATE_COLOR)) { + vertex_t t1 = *v1, t2 = *v2, t3 = *v3; + trapezoid_t traps[2]; + int n; + + t1.pos = p1; + t2.pos = p2; + t3.pos = p3; + t1.pos.w = c1.w; + t2.pos.w = c2.w; + t3.pos.w = c3.w; + + vertex_rhw_init(&t1); // 初始化 w + vertex_rhw_init(&t2); // 初始化 w + vertex_rhw_init(&t3); // 初始化 w + + // 拆分三角形为0-2个梯形，并且返回可用梯形数量 + n = trapezoid_init_triangle(traps, &t1, &t2, &t3); + + if (n >= 1) device_render_trap(device, &traps[0]); + if (n >= 2) device_render_trap(device, &traps[1]); + } + + if (render_state & RENDER_STATE_WIREFRAME) { // 线框绘制 + device_draw_line(device, (int)p1.x, (int)p1.y, (int)p2.x, (int)p2.y, device->foreground); + device_draw_line(device, (int)p1.x, (int)p1.y, (int)p3.x, (int)p3.y, device->foreground); + device_draw_line(device, (int)p3.x, (int)p3.y, (int)p2.x, (int)p2.y, device->foreground); + } +} + + +//===================================================================== +// Win32 窗口及图形绘制：为 device 提供一个 DibSection 的 FB +//===================================================================== +int screen_w, screen_h, screen_exit = 0; +int screen_mx = 0, screen_my = 0, screen_mb = 0; +int screen_keys[512]; // 当前键盘按下状态 +static HWND screen_handle = NULL; // 主窗口 HWND +static HDC screen_dc = NULL; // 配套的 HDC +static HBITMAP screen_hb = NULL; // DIB +static HBITMAP screen_ob = NULL; // 老的 BITMAP +unsigned char *screen_fb = NULL; // frame buffer +long screen_pitch = 0; + +int screen_init(int w, int h, const TCHAR *title); // 屏幕初始化 +int screen_close(void); // 关闭屏幕 +void screen_dispatch(void); // 处理消息 +void screen_update(void); // 显示 FrameBuffer + +// win32 event handler +static LRESULT screen_events(HWND, UINT, WPARAM, LPARAM); + +#ifdef _MSC_VER +#pragma comment(lib, "gdi32.lib") +#pragma comment(lib, "user32.lib") +#endif + +// 初始化窗口并设置标题 +int screen_init(int w, int h, const TCHAR *title) { + WNDCLASS wc = { CS_BYTEALIGNCLIENT, (WNDPROC)screen_events, 0, 0, 0, + NULL, NULL, NULL, NULL, _T("SCREEN3.1415926") }; + BITMAPINFO bi = { { sizeof(BITMAPINFOHEADER), w, -h, 1, 32, BI_RGB, + w * h * 4, 0, 0, 0, 0 } }; + RECT rect = { 0, 0, w, h }; + int wx, wy, sx, sy; + LPVOID ptr; + HDC hDC; + + screen_close(); + + wc.hbrBackground = (HBRUSH)GetStockObject(BLACK_BRUSH); + wc.hInstance = GetModuleHandle(NULL); + wc.hCursor = LoadCursor(NULL, IDC_ARROW); + if (!RegisterClass(&wc)) return -1; + + screen_handle = CreateWindow(_T("SCREEN3.1415926"), title, + WS_OVERLAPPED | WS_CAPTION | WS_SYSMENU | WS_MINIMIZEBOX, + 0, 0, 0, 0, NULL, NULL, wc.hInstance, NULL); + if (screen_handle == NULL) return -2; + + screen_exit = 0; + hDC = GetDC(screen_handle); + screen_dc = CreateCompatibleDC(hDC); + ReleaseDC(screen_handle, hDC); + + screen_hb = CreateDIBSection(screen_dc, &bi, DIB_RGB_COLORS, &ptr, 0, 0); + if (screen_hb == NULL) return -3; + + screen_ob = (HBITMAP)SelectObject(screen_dc, screen_hb); + screen_fb = (unsigned char*)ptr; + screen_w = w; + screen_h = h; + screen_pitch = w * 4; + + AdjustWindowRect(&rect, GetWindowLong(screen_handle, GWL_STYLE), 0); + wx = rect.right - rect.left; + wy = rect.bottom - rect.top; + sx = (GetSystemMetrics(SM_CXSCREEN) - wx) / 2; + sy = (GetSystemMetrics(SM_CYSCREEN) - wy) / 2; + if (sy < 0) sy = 0; + SetWindowPos(screen_handle, NULL, sx, sy, wx, wy, (SWP_NOCOPYBITS | SWP_NOZORDER | SWP_SHOWWINDOW)); + SetForegroundWindow(screen_handle); + + ShowWindow(screen_handle, SW_NORMAL); + screen_dispatch(); + + memset(screen_keys, 0, sizeof(int) * 512); + memset(screen_fb, 0, w * h * 4); + + return 0; +} + +int screen_close(void) { + if (screen_dc) { + if (screen_ob) { + SelectObject(screen_dc, screen_ob); + screen_ob = NULL; + } + DeleteDC(screen_dc); + screen_dc = NULL; + } + if (screen_hb) { + DeleteObject(screen_hb); + screen_hb = NULL; + } + if (screen_handle) { + CloseWindow(screen_handle); + screen_handle = NULL; + } + return 0; +} + +static LRESULT screen_events(HWND hWnd, UINT msg, + WPARAM wParam, LPARAM lParam) { + switch (msg) { + case WM_CLOSE: screen_exit = 1; break; + case WM_KEYDOWN: screen_keys[wParam & 511] = 1; break; + case WM_KEYUP: screen_keys[wParam & 511] = 0; break; + default: return DefWindowProc(hWnd, msg, wParam, lParam); + } + return 0; +} + +void screen_dispatch(void) { + MSG msg; + while (1) { + if (!PeekMessage(&msg, NULL, 0, 0, PM_NOREMOVE)) break; + if (!GetMessage(&msg, NULL, 0, 0)) break; + DispatchMessage(&msg); + } +} + +void screen_update(void) { + HDC hDC = GetDC(screen_handle); + BitBlt(hDC, 0, 0, screen_w, screen_h, screen_dc, 0, 0, SRCCOPY); + ReleaseDC(screen_handle, hDC); + screen_dispatch(); +} + + +//===================================================================== +// 主程序 +//===================================================================== +vertex_t mesh[8] = { + { { -1, -1, 1, 1 }, { 0, 0 }, { 1.0f, 0.2f, 0.2f }, 1 }, + { { 1, -1, 1, 1 }, { 0, 1 }, { 0.2f, 1.0f, 0.2f }, 1 }, + { { 1, 1, 1, 1 }, { 1, 1 }, { 0.2f, 0.2f, 1.0f }, 1 }, + { { -1, 1, 1, 1 }, { 1, 0 }, { 1.0f, 0.2f, 1.0f }, 1 }, + { { -1, -1, -1, 1 }, { 0, 0 }, { 1.0f, 1.0f, 0.2f }, 1 }, + { { 1, -1, -1, 1 }, { 0, 1 }, { 0.2f, 1.0f, 1.0f }, 1 }, + { { 1, 1, -1, 1 }, { 1, 1 }, { 1.0f, 0.3f, 0.3f }, 1 }, + { { -1, 1, -1, 1 }, { 1, 0 }, { 0.2f, 1.0f, 0.3f }, 1 }, +}; + +void draw_plane(device_t *device, int a, int b, int c, int d) { + vertex_t p1 = mesh[a], p2 = mesh[b], p3 = mesh[c], p4 = mesh[d]; + p1.tc.u = 0, p1.tc.v = 0, p2.tc.u = 0, p2.tc.v = 1; + p3.tc.u = 1, p3.tc.v = 1, p4.tc.u = 1, p4.tc.v = 0; + device_draw_primitive(device, &p1, &p2, &p3); + device_draw_primitive(device, &p3, &p4, &p1); +} + +void draw_box(device_t *device, float theta) { + matrix_t m; + matrix_set_rotate(&m, -1, -0.5, 1, theta); + device->transform.world = m; + transform_update(&device->transform); + draw_plane(device, 0, 1, 2, 3); + draw_plane(device, 7, 6, 5, 4); + draw_plane(device, 0, 4, 5, 1); + draw_plane(device, 1, 5, 6, 2); + draw_plane(device, 2, 6, 7, 3); + draw_plane(device, 3, 7, 4, 0); +} + +void camera_at_zero(device_t *device, float x, float y, float z) { + point_t eye = { x, y, z, 1 }, at = { 0, 0, 0, 1 }, up = { 0, 0, 1, 1 }; + matrix_set_lookat(&device->transform.view, &eye, &at, &up); + transform_update(&device->transform); +} + +void init_texture(device_t *device) { + static IUINT32 texture[256][256]; + int i, j; + for (j = 0; j < 256; j++) { + for (i = 0; i < 256; i++) { + int x = i / 32, y = j / 32; + texture[j][i] = ((x + y) & 1)? 0xffffff : 0x3fbcef; + } + } + device_set_texture(device, texture, 256 * 4, 256, 256); +} + +int main(void) +{ + device_t device; + int states[] = { RENDER_STATE_TEXTURE, RENDER_STATE_COLOR, RENDER_STATE_WIREFRAME }; + int indicator = 0; + int kbhit = 0; + float alpha = 1; + float pos = 3.5; + + TCHAR *title = _T("Mini3d (software render tutorial) - ") + _T("Left/Right: rotation, Up/Down: forward/backward, Space: switch state"); + + if (screen_init(800, 600, title)) + return -1; + + device_init(&device, 800, 600, screen_fb); + camera_at_zero(&device, 3, 0, 0); + + init_texture(&device); + device.render_state = RENDER_STATE_TEXTURE; + + while (screen_exit == 0 && screen_keys[VK_ESCAPE] == 0) { + screen_dispatch(); + device_clear(&device, 1); + camera_at_zero(&device, pos, 0, 0); + + if (screen_keys[VK_UP]) pos -= 0.01f; + if (screen_keys[VK_DOWN]) pos += 0.01f; + if (screen_keys[VK_LEFT]) alpha += 0.01f; + if (screen_keys[VK_RIGHT]) alpha -= 0.01f; + + if (screen_keys[VK_SPACE]) { + if (kbhit == 0) { + kbhit = 1; + if (++indicator >= 3) indicator = 0; + device.render_state = states[indicator]; + } + } else { + kbhit = 0; + } + + draw_box(&device, alpha); + screen_update(); + Sleep(1); + } + return 0; +} +