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more descriptive name for the blend-normal function because why there are two fucking standards for an alpha channel

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minjaesong
2022-10-31 01:52:40 +09:00
parent ccef7c32a0
commit 474279aefe
42 changed files with 122 additions and 108 deletions
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52
src/net/torvald/terrarum/Terrarum.kt
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@@ -479,46 +479,62 @@ fun blendDisable(batch: SpriteBatch) {
batch.disableBlending()
}
/**
* GLSource (foreground) must NOT have alpha premultiplied!
*/
fun blendNormal(batch: SpriteBatch) {
fun blendNormalStraightAlpha(batch: SpriteBatch) {
batch.enableBlending()
// batch.setBlendFunction(GL20.GL_SRC_ALPHA, GL20.GL_ONE_MINUS_SRC_ALPHA) // for premultiplied textures
batch.setBlendFunctionSeparate(GL20.GL_SRC_ALPHA, GL20.GL_ONE_MINUS_SRC_ALPHA, GL20.GL_ONE, GL20.GL_ONE_MINUS_SRC_ALPHA) // for not premultiplied textures
batch.setBlendFunctionSeparate(GL20.GL_SRC_ALPHA, GL20.GL_ONE_MINUS_SRC_ALPHA, GL20.GL_ONE, GL20.GL_ONE_MINUS_SRC_ALPHA)
// helpful links:
// - https://stackoverflow.com/questions/19674740/opengl-es2-premultiplied-vs-straight-alpha-blending#37869033
// - https://gamedev.stackexchange.com/questions/82741/normal-blend-mode-with-opengl-trouble
// - https://www.andersriggelsen.dk/glblendfunc.php
// - https://stackoverflow.com/questions/45781683/how-to-get-correct-sourceover-alpha-compositing-in-sdl-with-opengl
}
fun blendNormalPremultAlpha(batch: SpriteBatch) {
batch.enableBlending()
batch.setBlendFunction(GL20.GL_ONE, GL20.GL_ONE_MINUS_SRC_ALPHA)
// helpful links:
// - https://stackoverflow.com/questions/19674740/opengl-es2-premultiplied-vs-straight-alpha-blending#37869033
// - https://gamedev.stackexchange.com/questions/82741/normal-blend-mode-with-opengl-trouble
// - https://www.andersriggelsen.dk/glblendfunc.php
// - https://stackoverflow.com/questions/45781683/how-to-get-correct-sourceover-alpha-compositing-in-sdl-with-opengl
}
fun gdxClearAndSetBlend(color: Color) {
gdxClearAndSetBlend(color.r, color.g, color.b, color.a)
fun gdxClearAndEnableBlend(color: Color) {
gdxClearAndEnableBlend(color.r, color.g, color.b, color.a)
}
fun gdxClearAndSetBlend(r: Float, g: Float, b: Float, a: Float) {
fun gdxClearAndEnableBlend(r: Float, g: Float, b: Float, a: Float) {
Gdx.gl.glClearColor(r,g,b,a)
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT)
gdxSetBlend()
gdxEnableBlend()
}
fun gdxSetBlend() {
fun gdxEnableBlend() {
Gdx.gl.glEnable(GL20.GL_TEXTURE_2D)
Gdx.gl.glEnable(GL20.GL_BLEND)
}
fun gdxSetBlendNormal() {
gdxSetBlend()
// Gdx.gl.glBlendFunc(GL20.GL_SRC_ALPHA, GL20.GL_ONE_MINUS_SRC_ALPHA) // for premultiplied textures
Gdx.gl.glBlendFuncSeparate(GL20.GL_SRC_ALPHA, GL20.GL_ONE_MINUS_SRC_ALPHA, GL20.GL_ONE, GL20.GL_ONE_MINUS_SRC_ALPHA) // for not premultiplied textures
fun gdxBlendNormalStraightAlpha() {
gdxEnableBlend()
Gdx.gl.glBlendFuncSeparate(GL20.GL_SRC_ALPHA, GL20.GL_ONE_MINUS_SRC_ALPHA, GL20.GL_ONE, GL20.GL_ONE_MINUS_SRC_ALPHA)
// helpful links:
// - https://stackoverflow.com/questions/19674740/opengl-es2-premultiplied-vs-straight-alpha-blending#37869033
// - https://gamedev.stackexchange.com/questions/82741/normal-blend-mode-with-opengl-trouble
// - https://www.andersriggelsen.dk/glblendfunc.php
// - https://stackoverflow.com/questions/45781683/how-to-get-correct-sourceover-alpha-compositing-in-sdl-with-opengl
}
fun gdxSetBlendMul() {
gdxSetBlend()
fun gdxBlendNormalPremultAlpha() {
gdxEnableBlend()
Gdx.gl.glBlendFunc(GL20.GL_ONE, GL20.GL_ONE_MINUS_SRC_ALPHA)
// helpful links:
// - https://stackoverflow.com/questions/19674740/opengl-es2-premultiplied-vs-straight-alpha-blending#37869033
// - https://gamedev.stackexchange.com/questions/82741/normal-blend-mode-with-opengl-trouble
// - https://www.andersriggelsen.dk/glblendfunc.php
// - https://stackoverflow.com/questions/45781683/how-to-get-correct-sourceover-alpha-compositing-in-sdl-with-opengl
}
fun gdxBlendMul() {
gdxEnableBlend()
Gdx.gl.glBlendFunc(GL20.GL_DST_COLOR, GL20.GL_ONE_MINUS_SRC_ALPHA)
}
@@ -532,7 +548,7 @@ object BlendMode {
when (mode) {
SCREEN -> blendScreen(batch)
MULTIPLY -> blendMul(batch)
NORMAL -> blendNormal(batch)
NORMAL -> blendNormalStraightAlpha(batch)
//MAX -> blendLightenOnly() // not supported by GLES -- use shader
else -> throw Error("Unknown blend mode: $mode")
}