trying to work on issue #15 and I'm stumped

assets/tiling.frag

@@ -30,6 +30,7 @@ uniform sampler2D tilemap; // RGBA8888
 
 uniform sampler2D tilesAtlas; // terrain, wire, fluids, etc.
 uniform sampler2D tilesBlendAtlas; // weather mix (e.g. yellowed grass)
+uniform sampler2D backbuffer;
 uniform float tilesBlend = 0.0; // percentage of blending [0f..1f]. 0: draws tilesAtlas, 1: draws tilesBlendAtlas
 
 uniform ivec2 tilesInAtlas = ivec2(256, 256);
@@ -67,6 +68,7 @@ void main() {
     // READ THE FUCKING MANUAL, YOU DONKEY !! //
     // This code purposedly uses flipped fragcoord. //
     // Make sure you don't use gl_FragCoord unknowingly! //
+    // Remember, if there's a compile error, shader SILENTLY won't do anything //
 
 
     // default gl_FragCoord takes half-integer (represeting centre of the pixel) -- could be useful for phys solver?
@@ -109,6 +111,11 @@ void main() {
 
     vec4 finalBreakage = texture2D(tilesAtlas, finalUVCoordForBreakage);
 
-    gl_FragColor = colourFilter * (mix(finalTile, finalBreakage, finalBreakage.a));
+    vec4 finalColor = mix(finalTile, finalBreakage, finalBreakage.a);
+    vec4 backbufferColor = texture2D(backbuffer, gl_FragCoord.xy / screenDimension);
+
+    //gl_FragColor = colourFilter * finalColor;
+    //                                                             v
+    gl_FragColor = colourFilter * mix(backbufferColor, finalColor, 1);
 
 }

src/net/torvald/terrarum/AppLoader.java

@@ -222,15 +222,9 @@ public class AppLoader implements ApplicationListener {
         logo = new TextureRegion(new Texture(Gdx.files.internal("assets/graphics/logo_placeholder.tga")));
         logo.flip(false, true);
 
-        shaderBayerSkyboxFill = new ShaderProgram(Gdx.files.internal("assets/4096.vert"),
+        shaderBayerSkyboxFill = loadShader("assets/4096.vert", "assets/4096_bayer_skyboxfill.frag");
-                Gdx.files.internal("assets/4096_bayer_skyboxfill.frag")
+        shaderHicolour = loadShader("assets/4096.vert", "assets/hicolour.frag");
-        );
+        shaderColLUT = loadShader("assets/4096.vert", "assets/passthru.frag");
-        shaderHicolour = new ShaderProgram(Gdx.files.internal("assets/4096.vert"),
-                Gdx.files.internal("assets/hicolour.frag")
-        );
-        shaderColLUT = new ShaderProgram(Gdx.files.internal("assets/4096.vert"),
-                Gdx.files.internal("assets/passthru.frag")
-        );
 
         fullscreenQuad = new Mesh(
                 true, 4, 6,
@@ -464,9 +458,9 @@ public class AppLoader implements ApplicationListener {
         defaultSaveDir = defaultDir + "/Saves";
         configDir = defaultDir + "/config.json";
 
-        System.out.println("os.name = $OSName (with identifier $operationSystem)");
+        System.out.println(String.format("os.name = %s (with identifier %s)", OSName, operationSystem));
-        System.out.println("os.version = $OSVersion");
+        System.out.println(String.format("os.version = %s", OSVersion));
-        System.out.println("default directory: $defaultDir");
+        System.out.println(String.format("default directory: %s", defaultDir));
     }
 
     private void createDirs() {
@@ -634,15 +628,25 @@ public class AppLoader implements ApplicationListener {
 
     // //
 
-    public static final void printdbg(Object obj, Object message) {
+    public static void printdbg(Object obj, Object message) {
         if (IS_DEVELOPMENT_BUILD || getConfigBoolean("forcedevbuild")) {
             System.out.println("[" + obj.getClass().getSimpleName() + "] " + message.toString());
         }
     }
 
-    public static final void printdbgerr(Object obj, Object message) {
+    public static void printdbgerr(Object obj, Object message) {
         if (IS_DEVELOPMENT_BUILD || getConfigBoolean("forcedevbuild")) {
             System.err.println("[" + obj.getClass().getSimpleName() + "] " + message.toString());
         }
     }
+
+    public static ShaderProgram loadShader(String vert, String frag) {
+        ShaderProgram s = new ShaderProgram(Gdx.files.internal(vert), Gdx.files.internal(frag));
+
+        if (s.getLog().contains("error C")) {
+            throw new Error(String.format("Shader program loaded with %s, %s failed:\n%s", vert, frag, s.getLog()));
+        }
+
+        return s;
+    }
 }

src/net/torvald/terrarum/PostProcessor.kt

@@ -50,7 +50,6 @@ object PostProcessor {
             fbo.colorBufferTexture.bind(0)
 
             shader?.begin()
-            shader?.setUniformf("resolution", AppLoader.appConfig.width.toFloat(), AppLoader.appConfig.height.toFloat())
             shader?.setUniformMatrix("u_projTrans", projMat)
             shader?.setUniformi("u_texture", 0)
             AppLoader.fullscreenQuad.render(shader, GL20.GL_TRIANGLES)

src/net/torvald/terrarum/Terrarum.kt

@@ -328,18 +328,18 @@ object Terrarum : Screen {
 
 
         ShaderProgram.pedantic = false
-        shaderBlur = ShaderProgram(Gdx.files.internal("assets/blur.vert"), Gdx.files.internal("assets/blur.frag"))
+        shaderBlur = AppLoader.loadShader("assets/blur.vert", "assets/blur.frag")
 
 
         if (getConfigBoolean("fxdither")) {
-            shaderBayer = ShaderProgram(Gdx.files.internal("assets/4096.vert"), Gdx.files.internal("assets/4096_bayer.frag"))
+            shaderBayer = AppLoader.loadShader("assets/4096.vert", "assets/4096_bayer.frag")
             shaderBayer.begin()
             shaderBayer.setUniformf("rcount", 64f)
             shaderBayer.setUniformf("gcount", 64f)
             shaderBayer.setUniformf("bcount", 64f)
             shaderBayer.end()
 
-            shaderSkyboxFill = ShaderProgram(Gdx.files.internal("assets/4096.vert"), Gdx.files.internal("assets/4096_bayer_skyboxfill.frag"))
+            shaderSkyboxFill = AppLoader.loadShader("assets/4096.vert", "assets/4096_bayer_skyboxfill.frag")
             shaderSkyboxFill.begin()
             shaderSkyboxFill.setUniformf("rcount", 64f)
             shaderSkyboxFill.setUniformf("gcount", 64f)
@@ -347,15 +347,15 @@ object Terrarum : Screen {
             shaderSkyboxFill.end()
         }
         else {
-            shaderBayer = ShaderProgram(Gdx.files.internal("assets/4096.vert"), Gdx.files.internal("assets/passthru.frag"))
+            shaderBayer = AppLoader.loadShader("assets/4096.vert", "assets/passthru.frag")
-            shaderSkyboxFill = ShaderProgram(Gdx.files.internal("assets/4096.vert"), Gdx.files.internal("assets/skyboxfill.frag"))
+            shaderSkyboxFill = AppLoader.loadShader("assets/4096.vert", "assets/skyboxfill.frag")
         }
 
 
-        shaderBlendGlow = ShaderProgram(Gdx.files.internal("assets/blendGlow.vert"), Gdx.files.internal("assets/blendGlow.frag"))
+        shaderBlendGlow = AppLoader.loadShader("assets/blendGlow.vert", "assets/blendGlow.frag")
 
-        shaderRGBOnly = ShaderProgram(Gdx.files.internal("assets/4096.vert"), Gdx.files.internal("assets/rgbonly.frag"))
+        shaderRGBOnly = AppLoader.loadShader("assets/4096.vert", "assets/rgbonly.frag")
-        shaderAtoGrey = ShaderProgram(Gdx.files.internal("assets/4096.vert"), Gdx.files.internal("assets/aonly.frag"))
+        shaderAtoGrey = AppLoader.loadShader("assets/4096.vert", "assets/aonly.frag")
 
 
         if (!shaderBlendGlow.isCompiled) {
@@ -625,19 +625,20 @@ fun blendDisable(batch: SpriteBatch? = null) {
 }
 
 fun gdxClearAndSetBlend(r: Float, g: Float, b: Float, a: Float) {
-    Gdx.gl.glClearColor(0f,0f,0f,0f)
+    Gdx.gl.glClearColor(r,g,b,a)
     Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT)
     Gdx.gl.glEnable(GL20.GL_TEXTURE_2D)
     Gdx.gl.glEnable(GL20.GL_BLEND)
 
-    // this assumens premultiplied alpha?
+    // ALPHA *MUST BE* PREMULTIPLIED //
-    //Gdx.gl.glBlendFunc(GL20.GL_SRC_ALPHA, GL20.GL_ONE_MINUS_SRC_ALPHA)
-
-    // ALPHA MUST NOT BE PREMULTIPLIED //
-    // we're using separate blend func to accomodate not-premultiplied alpha
-    Gdx.gl.glBlendFuncSeparate(GL20.GL_SRC_ALPHA, GL20.GL_ONE_MINUS_SRC_ALPHA, GL20.GL_SRC_ALPHA, GL20.GL_ONE)
-    Gdx.gl.glBlendEquation(GL20.GL_FUNC_ADD)
 
+    // 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

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

@@ -238,7 +238,7 @@ object IngameRenderer {
             }
 
             setCameraPosition(0f, 0f)
-            BlocksDrawer.drawWall(batch.projectionMatrix)
+            BlocksDrawer.drawWall(batch.projectionMatrix, fboRGB)
 
             batch.inUse {
                 moveCameraToWorldCoord()
@@ -247,7 +247,7 @@ object IngameRenderer {
             }
 
             setCameraPosition(0f, 0f)
-            BlocksDrawer.drawTerrain(batch.projectionMatrix)
+            BlocksDrawer.drawTerrain(batch.projectionMatrix, fboRGB)
 
             batch.inUse {
                 /////////////////
@@ -262,7 +262,7 @@ object IngameRenderer {
             }
 
             setCameraPosition(0f, 0f)
-            BlocksDrawer.drawFront(batch.projectionMatrix, false) // blue coloured filter of water, etc.
+            BlocksDrawer.drawFront(batch.projectionMatrix, false, fboRGB) // blue coloured filter of water, etc.
 
             batch.inUse {
                 FeaturesDrawer.drawEnvOverlay(batch)

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

@@ -2,21 +2,18 @@ package net.torvald.terrarum.worlddrawer
 
 import com.badlogic.gdx.Gdx
 import com.badlogic.gdx.graphics.*
-import com.badlogic.gdx.graphics.glutils.ShaderProgram
+import com.badlogic.gdx.graphics.glutils.FrameBuffer
 import com.badlogic.gdx.math.Matrix4
+import net.torvald.terrarum.*
 import net.torvald.terrarum.AppLoader.printdbg
-import net.torvald.terrarum.ModMgr
 import net.torvald.terrarum.blockproperties.Block
 import net.torvald.terrarum.blockproperties.BlockCodex
-import net.torvald.terrarum.ceilInt
-import net.torvald.terrarum.floorInt
 import net.torvald.terrarum.gameworld.GameWorld
 import net.torvald.terrarum.gameworld.PairedMapLayer
 import net.torvald.terrarum.gameworld.fmod
 import net.torvald.terrarum.modulebasegame.gameworld.GameWorldExtension
 import net.torvald.terrarum.modulebasegame.gameworld.WorldSimulator
 import net.torvald.terrarum.modulebasegame.gameworld.WorldTime
-import net.torvald.terrarum.roundInt
 import net.torvald.terrarumsansbitmap.gdx.TextureRegionPack
 import java.io.BufferedOutputStream
 import java.io.File
@@ -89,7 +86,7 @@ internal object BlocksDrawer {
 
 
     private lateinit var tilesQuad: Mesh
-    private val shader = ShaderProgram(Gdx.files.internal("assets/4096.vert"), Gdx.files.internal("assets/tiling.frag"))
+    private val shader = AppLoader.loadShader("assets/4096.vert", "assets/tiling.frag")
 
     init {
         printdbg(this, "Unpacking textures...")
@@ -350,33 +347,33 @@ internal object BlocksDrawer {
         drawTiles(FLUID)
     }
 
-    internal fun drawWall(projectionMatrix: Matrix4) {
+    internal fun drawWall(projectionMatrix: Matrix4, backbuffer: FrameBuffer) {
         // blend normal
         Gdx.gl.glEnable(GL20.GL_TEXTURE_2D)
         Gdx.gl.glEnable(GL20.GL_BLEND)
         Gdx.gl.glBlendFunc(GL20.GL_SRC_ALPHA, GL20.GL_ONE_MINUS_SRC_ALPHA)
 
-        renderUsingBuffer(WALL, projectionMatrix)
+        renderUsingBuffer(WALL, projectionMatrix, backbuffer)
     }
 
-    internal fun drawTerrain(projectionMatrix: Matrix4) {
+    internal fun drawTerrain(projectionMatrix: Matrix4, backbuffer: FrameBuffer) {
         // blend normal
         Gdx.gl.glEnable(GL20.GL_TEXTURE_2D)
         Gdx.gl.glEnable(GL20.GL_BLEND)
         Gdx.gl.glBlendFunc(GL20.GL_SRC_ALPHA, GL20.GL_ONE_MINUS_SRC_ALPHA)
 
-        renderUsingBuffer(TERRAIN, projectionMatrix)
+        renderUsingBuffer(TERRAIN, projectionMatrix, backbuffer)
-        renderUsingBuffer(FLUID, projectionMatrix)
+        renderUsingBuffer(FLUID, projectionMatrix, backbuffer)
     }
 
-    internal fun drawFront(projectionMatrix: Matrix4, drawWires: Boolean) {
+    internal fun drawFront(projectionMatrix: Matrix4, drawWires: Boolean, backbuffer: FrameBuffer) {
         // blend mul
         Gdx.gl.glEnable(GL20.GL_TEXTURE_2D)
         Gdx.gl.glEnable(GL20.GL_BLEND)
         Gdx.gl.glBlendFunc(GL20.GL_DST_COLOR, GL20.GL_ONE_MINUS_SRC_ALPHA)
 
         // let's just not MUL on terrain, make it FLUID only...
-        renderUsingBuffer(FLUID, projectionMatrix)
+        renderUsingBuffer(FLUID, projectionMatrix, backbuffer)
 
 
 
@@ -386,7 +383,7 @@ internal object BlocksDrawer {
         Gdx.gl.glBlendFunc(GL20.GL_SRC_ALPHA, GL20.GL_ONE_MINUS_SRC_ALPHA)
 
         if (drawWires) {
-            renderUsingBuffer(WIRE, projectionMatrix)
+            renderUsingBuffer(WIRE, projectionMatrix, backbuffer)
         }
     }
 
@@ -688,7 +685,7 @@ internal object BlocksDrawer {
 
     private var _tilesBufferAsTex: Texture = Texture(1, 1, Pixmap.Format.RGBA8888)
 
-    private fun renderUsingBuffer(mode: Int, projectionMatrix: Matrix4) {
+    private fun renderUsingBuffer(mode: Int, projectionMatrix: Matrix4, backbuffer: FrameBuffer) {
         //Gdx.gl.glClearColor(.094f, .094f, .094f, 0f)
         //Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT)
 
@@ -731,6 +728,7 @@ internal object BlocksDrawer {
         _tilesBufferAsTex.dispose()
         _tilesBufferAsTex = Texture(tilesBuffer)
         _tilesBufferAsTex.setFilter(Texture.TextureFilter.Nearest, Texture.TextureFilter.Nearest)
+        backbuffer.colorBufferTexture.bind(3)
         tilesTerrainBlend.texture.bind(2)
         _tilesBufferAsTex.bind(1) // trying 1 and 0...
         tileAtlas.texture.bind(0) // for some fuck reason, it must be bound as last
@@ -742,6 +740,7 @@ internal object BlocksDrawer {
         shader.setUniformi("tilesAtlas", 0)
         shader.setUniformi("tilesBlendAtlas", 2)
         shader.setUniformi("tilemap", 1)
+        shader.setUniformi("backbuffer", 3)
         shader.setUniformi("tilemapDimension", tilesBuffer.width, tilesBuffer.height)
         shader.setUniformf("tilesInAxes", tilesInHorizontal.toFloat(), tilesInVertical.toFloat())
         shader.setUniformi("cameraTranslation", WorldCamera.x fmod TILE_SIZE, WorldCamera.y fmod TILE_SIZE) // usage of 'fmod' and '%' were depend on the for_x_start, which I can't just do naive int div