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tried to tackle the alpha blending issue but it seems the problem is on somewhere far far away

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This commit is contained in:
minjaesong
2022-04-20 17:53:47 +09:00
parent cfcdb9c998
commit b3a27bb428
6 changed files with 36 additions and 51 deletions
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34
src/net/torvald/terrarum/Terrarum.kt
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@@ -373,14 +373,17 @@ infix fun Color.mulAndAssign(other: Color): Color {
return this
}
/**
* Use demultiplier shader on GL Source (foreground) if source has semitransparency
*/
fun blendMul(batch: SpriteBatch) {
// will break if the colour image contains semitransparency
batch.enableBlending()
batch.setBlendFunction(GL20.GL_DST_COLOR, GL20.GL_ONE_MINUS_SRC_ALPHA)
// batch.setBlendFunctionSeparate(GL20.GL_DST_COLOR, GL20.GL_ONE_MINUS_SRC_ALPHA, GL20.GL_DST_ALPHA, GL20.GL_SRC_ALPHA)
}
/**
* Use demultiplier shader on GL Source (foreground) if source has semitransparency
*/
fun blendScreen(batch: SpriteBatch) {
// will break if the colour image contains semitransparency
batch.enableBlending()
@@ -391,21 +394,13 @@ fun blendDisable(batch: SpriteBatch) {
batch.disableBlending()
}
/**
* GLSource (foreground) must NOT have alpha premultiplied!
*/
fun blendNormal(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
// ALPHA *MUST BE* PREMULTIPLIED //
// One way to tell:
// 1. Check (RGB) and (A) values.
// 2. If there exist a pixel such that max(R,G,B) > (A), then the image is NOT premultiplied.
// Easy way:
// Base game (mods/basegame/blocks/terrain.tga.gz) has impure window glass. When looking at the RGB channel only:
// premultipied if the glass looks very dark.
// not premultipied if the glass looks VERY GREEN.
// helpful links:
// - https://gamedev.stackexchange.com/questions/82741/normal-blend-mode-with-opengl-trouble
// - https://www.andersriggelsen.dk/glblendfunc.php
@@ -431,17 +426,6 @@ 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
// ALPHA *MUST BE* PREMULTIPLIED //
// One way to tell:
// 1. Check (RGB) and (A) values.
// 2. If there exist a pixel such that max(R,G,B) > (A), then the image is NOT premultiplied.
// Easy way:
// Base game (mods/basegame/blocks/terrain.tga.gz) has impure window glass. When looking at the RGB channel only:
// premultipied if the glass looks very dark.
// not premultipied if the glass looks VERY GREEN.
// helpful links:
// - https://gamedev.stackexchange.com/questions/82741/normal-blend-mode-with-opengl-trouble
// - https://www.andersriggelsen.dk/glblendfunc.php