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ebiten: Add shader builtin functions: imageSrcTextureSourceRegion

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Updates #1294
This commit is contained in:
Hajime Hoshi 2020-08-12 03:34:46 +09:00
parent d4042a5cfa
commit ed240b8393
1 changed files with 17 additions and 5 deletions
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22
shader.go
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@ -31,6 +31,7 @@ func init() {
shaderSuffix = `
var __imageDstTextureSize vec2
// imageSrcTextureSize returns the destination image's texture size in pixels.
func imageDstTextureSize() vec2 {
return __imageDstTextureSize
}
@ -39,18 +40,29 @@ func imageDstTextureSize() vec2 {
shaderSuffix += fmt.Sprintf(`
var __textureSizes [%[1]d]vec2
// imageSrcTextureSize returns the source image's texture size in pixels.
// As an image is a part of internal texture, the texture is usually bigger than the image.
// The texture's size is useful when you want to calculate pixels from texels.
func imageSrcTextureSize() vec2 {
return __textureSizes[0]
}
// The unit is texture0's texels.
// The unit is the source texture's texel.
var __textureSourceOffsets [%[2]d]vec2
// The unit is texture0's texels.
// The unit is the source texture's texel.
var __textureSourceRegionOrigin vec2
// The unit is texture0's texels.
// The unit is the source texture's texel.
var __textureSourceRegionSize vec2
// imageSrcTextureSourceRegion returns the source image's region (the origin and the size) on its texture.
// The unit is the source texture's texel.
//
// As an image is a part of internal texture, the image can be located at an arbitrary position on the texture.
func imageSrcTextureSourceRegion() (vec2, vec2) {
return __textureSourceRegionOrigin, __textureSourceRegionSize
}
`, graphics.ShaderImageNum, graphics.ShaderImageNum-1)
for i := 0; i < graphics.ShaderImageNum; i++ {
@ -62,12 +74,12 @@ var __textureSourceRegionSize vec2
// __t%d is a special variable for a texture variable.
shaderSuffix += fmt.Sprintf(`
func image%[1]dTextureAt(pos vec2) vec4 {
// pos is the position in texture0's texels.
// pos is the position in texels of the source texture (= 0th image's texture).
return texture2D(__t%[1]d, %[2]s)
}
func image%[1]dTextureBoundsAt(pos vec2) vec4 {
// pos is the position in texture0's texels.
// pos is the position in texels of the source texture (= 0th image's texture).
return texture2D(__t%[1]d, %[2]s) *
step(__textureSourceRegionOrigin.x, pos.x) *
(1 - step(__textureSourceRegionOrigin.x + __textureSourceRegionSize.x, pos.x)) *