internal/graphics: use pixels for offsets

internal/graphics/shader.go

@@ -56,7 +56,7 @@ func imageDstRegionOnTexture() (vec2, vec2) {
 	return __textureDestinationRegionOrigin, __textureDestinationRegionSize
 }
 
-// The unit is the source texture's pixel or texel.
+// The unit is the source texture's pixel.
 var __textureSourceOffsets [%[2]d]vec2
 
 // The unit is the source texture's pixel or texel.
@@ -82,7 +82,7 @@ func imageSrcRegionOnTexture() (vec2, vec2) {
 			case shaderir.Pixel:
 				pos = fmt.Sprintf("pos + __textureSourceOffsets[%d]", i-1)
 			case shaderir.Texel:
-				pos = fmt.Sprintf("(pos + __textureSourceOffsets[%d]) * __textureSizes[0] / __textureSizes[%d]", i-1, i)
+				pos = fmt.Sprintf("(pos * __textureSizes[0] + __textureSourceOffsets[%d]) / __textureSizes[%d]", i-1, i)
 			default:
 				return "", fmt.Errorf("graphics: unexpected unit: %d", unit)
 			}

internal/graphicscommand/command.go

@@ -621,10 +621,6 @@ func (q *commandQueue) prependPreservedUniforms(uniforms []uint32, shader *Shade
 		srcRegion.Y /= float32(h)
 		srcRegion.Width /= float32(w)
 		srcRegion.Height /= float32(h)
-		for i := range offsets {
-			offsets[i][0] /= float32(w)
-			offsets[i][1] /= float32(h)
-		}
 	}
 
 	// Set the source offsets.

shader_test.go

@@ -1761,3 +1761,54 @@ func Fragment(position vec4, texCoord vec2, color vec4) vec4 {
 		}
 	}
 }
+
+func TestShaderDifferentTextureSizes(t *testing.T) {
+	src0 := ebiten.NewImageWithOptions(image.Rect(0, 0, 20, 4000), &ebiten.NewImageOptions{
+		Unmanaged: true,
+	}).SubImage(image.Rect(4, 1025, 6, 1028)).(*ebiten.Image)
+	defer src0.Dispose()
+
+	src1 := ebiten.NewImageWithOptions(image.Rect(0, 0, 4000, 20), &ebiten.NewImageOptions{
+		Unmanaged: true,
+	}).SubImage(image.Rect(2047, 7, 2049, 10)).(*ebiten.Image)
+	defer src1.Dispose()
+
+	src0.Fill(color.RGBA{0x10, 0x20, 0x30, 0xff})
+	src1.Fill(color.RGBA{0x30, 0x20, 0x10, 0xff})
+
+	for _, unit := range []string{"texel", "pixel"} {
+		unit := unit
+		t.Run(fmt.Sprintf("unit %s", unit), func(t *testing.T) {
+			shader, err := ebiten.NewShader([]byte(fmt.Sprintf(`//kage:unit %s
+
+package main
+
+func Fragment(position vec4, texCoord vec2, color vec4) vec4 {
+	return imageSrc0At(texCoord) + imageSrc1At(texCoord)
+}
+`, unit)))
+			if err != nil {
+				t.Fatal(err)
+			}
+			defer shader.Dispose()
+
+			dst := ebiten.NewImage(2, 3)
+			defer dst.Dispose()
+
+			op := &ebiten.DrawRectShaderOptions{}
+			op.Images[0] = src0
+			op.Images[1] = src1
+			dst.DrawRectShader(2, 3, shader, op)
+
+			for j := 0; j < 3; j++ {
+				for i := 0; i < 2; i++ {
+					got := dst.At(i, j).(color.RGBA)
+					want := color.RGBA{0x40, 0x40, 0x40, 0xff}
+					if !sameColors(got, want, 1) {
+						t.Errorf("dst.At(%d, %d): got: %v, want: %v", i, j, got, want)
+					}
+				}
+			}
+		})
+	}
+}