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

src/net/torvald/spriteanimation/AssembledSpriteAnimation.kt

@@ -1,5 +1,6 @@
 package net.torvald.spriteanimation
 
+import com.badlogic.gdx.graphics.Color
 import com.badlogic.gdx.graphics.Pixmap
 import com.badlogic.gdx.graphics.Texture
 import com.badlogic.gdx.graphics.g2d.SpriteBatch

src/net/torvald/terrarum/PostProcessor.kt

@@ -153,7 +153,6 @@ object PostProcessor : Disposable {
         else
             shaderPostNoDither
 
-
         App.getCurrentDitherTex().bind(1)
         fbo.colorBufferTexture.bind(0)
 

src/net/torvald/terrarum/Terrarum.kt

@@ -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

src/net/torvald/terrarum/modulebasegame/IngameRenderer.kt

@@ -12,7 +12,6 @@ import com.badlogic.gdx.utils.GdxRuntimeException
 import net.torvald.random.HQRNG
 import net.torvald.terrarum.*
 import net.torvald.terrarum.App.measureDebugTime
-import net.torvald.terrarum.App.printdbg
 import net.torvald.terrarum.TerrarumAppConfiguration.TILE_SIZE
 import net.torvald.terrarum.TerrarumAppConfiguration.TILE_SIZEF
 import net.torvald.terrarum.gameactors.ActorWithBody
@@ -83,7 +82,7 @@ object IngameRenderer : Disposable {
     val shaderKawaseUp: ShaderProgram
 
     val shaderBlendGlow: ShaderProgram
-    val shaderAlphaDither: ShaderProgram
+    val shaderForActors: ShaderProgram
 
     private val WIDTH = App.scr.width
     private val HEIGHT = App.scr.height
@@ -120,7 +119,7 @@ object IngameRenderer : Disposable {
         shaderAtoGrey = App.loadShaderFromClasspath("shaders/default.vert", "shaders/aonly.frag")
 
 
-        shaderAlphaDither = App.loadShaderFromClasspath("shaders/default.vert", "shaders/alphadither.frag")
+        shaderForActors = App.loadShaderFromClasspath("shaders/default.vert", "shaders/actors.frag")
         shaderBlendGlow = App.loadShaderFromClasspath("shaders/blendGlow.vert", "shaders/blendGlow.frag")
 
 
@@ -426,28 +425,24 @@ object IngameRenderer : Disposable {
 
         fboRGB.inAction(camera, batch) {
 
-            batch.inUse {
-                batch.shader = shaderAlphaDither
-                batch.color = Color.WHITE
-            }
-
             setCameraPosition(0f, 0f)
             BlocksDrawer.drawWall(batch.projectionMatrix, false)
 
             batch.inUse {
+                batch.shader = shaderForActors
+                batch.color = Color.WHITE
                 moveCameraToWorldCoord()
                 actorsRenderBehind?.forEach { it.drawBody(batch) }
-            }
-            batch.shader = shaderAlphaDither
-            batch.inUse {
                 particlesContainer?.forEach { it.drawBody(batch) }
             }
 
             setCameraPosition(0f, 0f)
             BlocksDrawer.drawTerrain(batch.projectionMatrix, false)
 
-            batch.shader = shaderAlphaDither
+            batch.shader = shaderForActors
             batch.inUse {
+                batch.shader = shaderForActors
+                batch.color = Color.WHITE
                 /////////////////
                 // draw actors //
                 /////////////////
@@ -464,6 +459,8 @@ object IngameRenderer : Disposable {
 
             batch.shader = null
             batch.inUse {
+                batch.shader = shaderForActors
+                batch.color = Color.WHITE
                 FeaturesDrawer.drawEnvOverlay(batch)
             }
         }
@@ -502,6 +499,12 @@ object IngameRenderer : Disposable {
                         lightTex.regionWidth * lightmapDownsample,
                         lightTex.regionHeight * lightmapDownsample
                 )
+
+                // if right texture coord for lightTex and fboRGB are obtainable, you can try this:
+                /*
+                vec4 skyboxColour = ...
+                gl_FragCoord = alphablend skyboxColour with (fboRGB * lightTex)
+                 */
             }
 
 
@@ -529,15 +532,13 @@ object IngameRenderer : Disposable {
 
         fboA.inAction(camera, batch) {
 
-            batch.inUse {
-                batch.shader = shaderAlphaDither
-                batch.color = Color.WHITE
-            }
-
             setCameraPosition(0f, 0f)
             BlocksDrawer.drawWall(batch.projectionMatrix, true)
 
             batch.inUse {
+                batch.shader = shaderForActors
+                batch.color = Color.WHITE
+
                 moveCameraToWorldCoord()
                 actorsRenderBehind?.forEach { it.drawGlow(batch) }
                 particlesContainer?.forEach { it.drawGlow(batch) }
@@ -569,6 +570,9 @@ object IngameRenderer : Disposable {
             Gdx.gl.glActiveTexture(GL20.GL_TEXTURE0) // so that batch that comes next will bind any tex to it
 
             batch.inUse {
+                batch.shader = null
+                batch.color = Color.WHITE
+
                 // draw world
                 batch.draw(fboA.colorBufferTexture, 0f, 0f)
                 batch.flush()
@@ -604,15 +608,13 @@ object IngameRenderer : Disposable {
     private fun drawOverlayActors(actors: List<ActorWithBody>?) {
         fboRGB_lightMixed.inActionF(camera, batch) {
 
-            batch.inUse {
-                batch.shader = shaderAlphaDither
-                batch.color = Color.WHITE
-            }
-
             setCameraPosition(0f, 0f)
             // BlocksDrawer.renderWhateverGlow_WALL
 
             batch.inUse {
+                batch.shader = shaderForActors
+                batch.color = Color.WHITE
+
                 moveCameraToWorldCoord()
                 actors?.forEach {
                     it.drawBody(batch)
@@ -867,7 +869,7 @@ object IngameRenderer : Disposable {
         shaderKawaseUp.dispose()
 
         shaderBlendGlow.dispose()
-        shaderAlphaDither.dispose()
+        shaderForActors.dispose()
 
         try { fboRGBexport.dispose() }
         catch (e: GdxRuntimeException) {}

src/net/torvald/terrarum/worlddrawer/BlocksDrawer.kt

@@ -85,7 +85,7 @@ internal object BlocksDrawer {
 
 
     private lateinit var tilesQuad: Mesh
-    private val shader = App.loadShaderFromClasspath("shaders/default.vert", "shaders/tiling_dither.frag")
+    private val shader = App.loadShaderFromClasspath("shaders/default.vert", "shaders/tiling.frag")
 
     init {
 

src/shaders/actors.frag

@@ -30,5 +30,4 @@ void main() {
     vec4 selvec = vec4(0.0, 0.0, 0.0, (alpha > bayerThreshold) ? 1.0 : 0.0);
 
     gl_FragColor = inColor * boolean.yyyx + selvec;
-//    gl_FragColor = inColor;
 }