Use builder to create a square with different colors for each vertex

[xushengbo]

I try to use builer to create a square with different colors for each vertex. Modify the relevant code as follows，But only the first color of the drawn box works. Can there only be one color?

ref_ptr myBuilder::createBox(const GeometryInfo& info, const StateInfo& stateInfo)
{
auto& subgraph = _boxes[std::make_pair(info, stateInfo)];
if (subgraph)
{
return subgraph;
}

uint32_t instanceCount = 1;
auto positions = instancePositions(info, instanceCount);
auto colors = instanceColors(info, instanceCount);

auto dx = info.dx;
auto dy = info.dy;
auto dz = info.dz;
auto origin = info.position - dx * 0.5f - dy * 0.5f - dz * 0.5f;
auto [t_origin, t_scale, t_top] = y_texcoord(stateInfo).value;

vec3 v000(origin);
vec3 v100(origin + dx);
vec3 v110(origin + dx + dy);
vec3 v010(origin + dy);
vec3 v001(origin + dz);
vec3 v101(origin + dx + dz);
vec3 v111(origin + dx + dy + dz);
vec3 v011(origin + dy + dz);

vec2 t00(0.0f, t_origin);
vec2 t01(0.0f, t_top);
vec2 t10(1.0f, t_origin);
vec2 t11(1.0f, t_top);

ref_ptr<vec3Array> vertices;
ref_ptr<vec3Array> normals;
ref_ptr<vec2Array> texcoords;
ref_ptr<ushortArray> indices;

if (stateInfo.wireframe)
{
    vec3 n0 = normalize(v000 - v111);
    vec3 n1 = normalize(v100 - v011);
    vec3 n2 = normalize(v110 - v001);
    vec3 n3 = normalize(v010 - v101);
    vec3 n4 = -n2;
    vec3 n5 = -n3;
    vec3 n6 = -n0;
    vec3 n7 = -n1;

    // set up vertex and index arrays
    vertices = vec3Array::create(
        { v000, v100, v110, v010,
         v001, v101, v111, v011 });

    normals = vec3Array::create(
        { n0, n1, n2, n3,
         n4, n5, n6, n7 });

    texcoords = vec2Array::create(
        { t00, t10, t11, t01,
         t00, t10, t11, t01 });

    indices = ushortArray::create(
		{ 0, 1, 1, 2, 2, 3, 3, 0,
		 0, 4, 1, 5, 2, 6, 3, 7,
		 4, 5, 5, 6, 6, 7, 7, 4  });
}
else
{
    vec3 n0 = normalize(cross(dx, dz));
    vec3 n1 = normalize(cross(dy, dz));
    vec3 n2 = -n0;
    vec3 n3 = -n1;
    vec3 n4 = normalize(cross(dy, dx));
    vec3 n5 = -n4;

    // set up vertex and index arrays
    vertices = vec3Array::create(
        { v000, v100, v101, v001,   // front
         v100, v110, v111, v101,   // right
         v110, v010, v011, v111,   // far
         v010, v000, v001, v011,   // left
         v010, v110, v100, v000,   // bottom
         v001, v101, v111, v011 }); // top

	 colors = vec4Array::create(
		{ 
          vec4(1.0f, 1.0f, 0.0f, 1.0f),
          vec4(1.0f, 0.0f, 0.0f, 1.0f),
		  vec4(0.0f, 1.0f, 0.0f, 1.0f),
		  vec4(0.0f, 0.0f, 1.0f, 1.0f),
		  
		  vec4(1.0f, 0.0f, 0.0f, 1.0f),
		  vec4(0.0f, 1.0f, 0.0f, 1.0f),
		  vec4(0.0f, 0.0f, 1.0f, 1.0f),
		  vec4(1.0f, 1.0f, 0.0f, 1.0f),

		  vec4(1.0f, 0.0f, 0.0f, 1.0f),
		  vec4(0.0f, 1.0f, 0.0f, 1.0f),
		  vec4(0.0f, 0.0f, 1.0f, 1.0f),
		  vec4(1.0f, 1.0f, 0.0f, 1.0f),

		  vec4(1.0f, 0.0f, 0.0f, 1.0f),
		  vec4(0.0f, 1.0f, 0.0f, 1.0f),
		  vec4(0.0f, 0.0f, 1.0f, 1.0f),
		  vec4(1.0f, 1.0f, 0.0f, 1.0f),

		  vec4(1.0f, 0.0f, 0.0f, 1.0f),
		  vec4(0.0f, 1.0f, 0.0f, 1.0f),
		  vec4(0.0f, 0.0f, 1.0f, 1.0f),
		  vec4(1.0f, 1.0f, 0.0f, 1.0f),

		  vec4(1.0f, 0.0f, 0.0f, 1.0f),
		  vec4(0.0f, 1.0f, 0.0f, 1.0f),
		  vec4(0.0f, 0.0f, 1.0f, 1.0f),
		  vec4(1.0f, 1.0f, 0.0f, 1.0f) 
         }
	);

    normals = vec3Array::create(
        { n0, n0, n0, n0,
         n1, n1, n1, n1,
         n2, n2, n2, n2,
         n3, n3, n3, n3,
         n4, n4, n4, n4,
         n5, n5, n5, n5 });

    texcoords = vec2Array::create(
        { t00, t10, t11, t01,
         t00, t10, t11, t01,
         t00, t10, t11, t01,
         t00, t10, t11, t01,
         t00, t10, t11, t01,
         t00, t10, t11, t01 });

    indices = ushortArray::create(
        { 0, 1, 2, 0, 2, 3,
         4, 5, 6, 4, 6, 7,
         8, 9, 10, 8, 10, 11,
         12, 13, 14, 12, 14, 15,
         16, 17, 18, 16, 18, 19,
         20, 21, 22, 20, 22, 23 });
}

if (info.transform != identity)
{
    transform(info.transform, vertices, normals);
}

// setup geometry
auto vid = VertexIndexDraw::create();

DataList arrays;
arrays.push_back(vertices);
if (normals) arrays.push_back(normals);
if (texcoords) arrays.push_back(texcoords);
if (colors) arrays.push_back(colors);
if (positions) arrays.push_back(positions);
vid->assignArrays(arrays);

vid->assignIndices(indices);
vid->indexCount = static_cast<uint32_t>(indices->size());
vid->instanceCount = instanceCount;

subgraph = decorateAndCompileIfRequired(info, stateInfo, vid);
return subgraph;

}

[jacky-wang7]

I can't see how you set the color.
I took a quick look at the VSG source code and it should be possible to set the color in geometryInfo.colors.

[robertosfield]

The vsg::Builder is meant to be have a simple interface and generate a relative small range of geometries. Trying to chase all possible combinations of what users might want really isn't what it's meant for.

If the class doesn't do exactly what you want out of the box just roll your own scene graph - the vsg::Builder source code illustrates what is one route to setting up vsg::StateGroup and vsg::DrawIndexed/Draw nodes. Have a look at vsgExamples for use of StateGroup/Draw/DrawIndex/Geometry/BindIndexBuffers etc.

[xushengbo]

Thank you very much for your reply, I understand the original design intention of the builder, recently drew the DTM with reference to the builder, and I would like to realize the function of drawing different colors for different elevation values, I will study it again. Thanks again