internal/graphics: add uniform variables for source image sizes

Updates #1870

internal/graphics/shader.go

@@ -63,14 +63,14 @@ var __imageSrcOffsets [%[2]d]vec2
 var __imageSrcRegionOrigin vec2
 
 // The unit is the source texture's pixel or texel.
-var __imageSrcRegionSize vec2
+var __imageSrcRegionSizes [%[1]d]vec2
 
 // imageSrcRegionOnTexture returns the source image's region (the origin and the size) on its texture.
 // The unit is the source texture's pixel or texel.
 //
 // As an image is a part of internal texture, the image can be located at an arbitrary position on the texture.
 func imageSrcRegionOnTexture() (vec2, vec2) {
-	return __imageSrcRegionOrigin, __imageSrcRegionSize
+	return __imageSrcRegionOrigin, __imageSrcRegionSizes[0]
 }
 `, ShaderImageCount, ShaderImageCount-1)
 
@@ -97,7 +97,7 @@ func imageSrc%[1]dUnsafeAt(pos vec2) vec4 {
 func imageSrc%[1]dAt(pos vec2) vec4 {
 	// pos is the position of the source texture (= 0th image's texture).
 	// If pos is in the region, the result is (1, 1). Otherwise, either element is 0.
-	in := step(__imageSrcRegionOrigin, pos) - step(__imageSrcRegionOrigin + __imageSrcRegionSize, pos)
+	in := step(__imageSrcRegionOrigin, pos) - step(__imageSrcRegionOrigin + __imageSrcRegionSizes[%[1]d], pos)
 	return __texelAt(__t%[1]d, %[2]s) * in.x * in.y
 }
 `, i, pos)

internal/graphics/vertex.go

@@ -25,29 +25,22 @@ const (
 	// Any shaders in Ebitengine must have these uniform variables.
 	PreservedUniformVariablesCount = 1 + // the destination texture size
 		1 + // the source texture sizes array
-		1 + // the destination image region's origin
-		1 + // the destination image region's size
+		1 + // the destination image region origin
+		1 + // the destination image region size
 		1 + // the offsets array of the second and the following source images
-		1 + // the source image region's origin
-		1 + // the source image region's size
+		1 + // the source image region origin
+		1 + // the source image region sizes array
 		1 // the projection matrix
 
-	TextureDestinationSizeUniformVariableIndex       = 0
-	TextureSourceSizesUniformVariableIndex           = 1
-	ImageDestinationRegionOriginUniformVariableIndex = 2
-	ImageDestinationRegionSizeUniformVariableIndex   = 3
-	ImageSourceOffsetsUniformVariableIndex           = 4
-	ImageSourceRegionOriginUniformVariableIndex      = 5
-	ImageSourceRegionSizeUniformVariableIndex        = 6
-	ProjectionMatrixUniformVariableIndex             = 7
+	ProjectionMatrixUniformVariableIndex = 7
 
 	PreservedUniformUint32Count = 2 + // the destination texture size
 		2*ShaderImageCount + // the source texture sizes array
-		2 + // the destination image region's origin
-		2 + // the destination image region's size
+		2 + // the destination image region origin
+		2 + // the destination image region size
 		2*(ShaderImageCount-1) + // the offsets array of the second and the following source images
-		2 + // the source image region's origin
-		2 + // the source image region's size
+		2 + // the source image region origin
+		2*ShaderImageCount + // the source image region sizes array
 		16 // the projection matrix
 )
 

internal/graphicscommand/command.go

@@ -709,9 +709,11 @@ func (q *commandQueue) prependPreservedUniforms(uniforms []uint32, shader *Shade
 		dstRegion.Height /= float32(dh)
 	}
 
-	// Set the destination region.
+	// Set the destination region origin.
 	uniforms[10] = math.Float32bits(dstRegion.X)
 	uniforms[11] = math.Float32bits(dstRegion.Y)
+
+	// Set the destination region size.
 	uniforms[12] = math.Float32bits(dstRegion.Width)
 	uniforms[13] = math.Float32bits(dstRegion.Height)
 
@@ -723,36 +725,46 @@ func (q *commandQueue) prependPreservedUniforms(uniforms []uint32, shader *Shade
 		srcRegion.Height /= float32(h)
 	}
 
-	// Set the source offsets.
+	// Set the source region offsets.
 	uniforms[14] = math.Float32bits(offsets[0][0])
 	uniforms[15] = math.Float32bits(offsets[0][1])
 	uniforms[16] = math.Float32bits(offsets[1][0])
 	uniforms[17] = math.Float32bits(offsets[1][1])
 	uniforms[18] = math.Float32bits(offsets[2][0])
 	uniforms[19] = math.Float32bits(offsets[2][1])
 
-	// Set the source region of texture0.
+	// Set the source region origin.
 	uniforms[20] = math.Float32bits(srcRegion.X)
 	uniforms[21] = math.Float32bits(srcRegion.Y)
+
+	// Set the source region sizes.
+	// TODO: Set a different sizes for a different source (#1870).
 	uniforms[22] = math.Float32bits(srcRegion.Width)
 	uniforms[23] = math.Float32bits(srcRegion.Height)
-
-	uniforms[24] = math.Float32bits(2 / float32(dw))
-	uniforms[25] = 0
-	uniforms[26] = 0
-	uniforms[27] = 0
-	uniforms[28] = 0
-	uniforms[29] = math.Float32bits(2 / float32(dh))
-	uniforms[30] = 0
+	uniforms[24] = math.Float32bits(srcRegion.Width)
+	uniforms[25] = math.Float32bits(srcRegion.Height)
+	uniforms[26] = math.Float32bits(srcRegion.Width)
+	uniforms[27] = math.Float32bits(srcRegion.Height)
+	uniforms[28] = math.Float32bits(srcRegion.Width)
+	uniforms[29] = math.Float32bits(srcRegion.Height)
+
+	// Set the projection matrix.
+	uniforms[30] = math.Float32bits(2 / float32(dw))
 	uniforms[31] = 0
 	uniforms[32] = 0
 	uniforms[33] = 0
-	uniforms[34] = math.Float32bits(1)
-	uniforms[35] = 0
-	uniforms[36] = math.Float32bits(-1)
-	uniforms[37] = math.Float32bits(-1)
+	uniforms[34] = 0
+	uniforms[35] = math.Float32bits(2 / float32(dh))
+	uniforms[36] = 0
+	uniforms[37] = 0
 	uniforms[38] = 0
-	uniforms[39] = math.Float32bits(1)
+	uniforms[39] = 0
+	uniforms[40] = math.Float32bits(1)
+	uniforms[41] = 0
+	uniforms[42] = math.Float32bits(-1)
+	uniforms[43] = math.Float32bits(-1)
+	uniforms[44] = 0
+	uniforms[45] = math.Float32bits(1)
 
 	return uniforms
 }