dithering on grad overlay

src/net/torvald/terrarum/UIFakeGradOverlay.kt

@@ -1,9 +1,13 @@
 package net.torvald.terrarum
 
+import com.badlogic.gdx.Gdx
 import com.badlogic.gdx.graphics.Camera
 import com.badlogic.gdx.graphics.Color
+import com.badlogic.gdx.graphics.GL20
 import com.badlogic.gdx.graphics.OrthographicCamera
 import com.badlogic.gdx.graphics.g2d.SpriteBatch
+import net.torvald.random.HQRNG
+import net.torvald.terrarum.modulebasegame.IngameRenderer
 import net.torvald.terrarum.ui.Toolkit
 import net.torvald.terrarum.ui.UICanvas
 
@@ -24,12 +28,31 @@ class UIFakeGradOverlay : UICanvas() {
 
     private val tex = CommonResourcePool.getAsTexture("title_halfgrad")
 
+    private val renderng = HQRNG()
+
     init {
         setAsAlwaysVisible()
     }
 
     override fun updateUI(delta: Float) {}
     override fun renderUI(batch: SpriteBatch, camera: Camera) {
+        batch.end()
+        val dither = App.getConfigBoolean("fx_dither")
+
+        if (dither) {
+            IngameRenderer.ditherPattern.bind(1)
+            Gdx.gl.glActiveTexture(GL20.GL_TEXTURE0) // so that batch that comes next will bind any tex to it
+        }
+
+
+        batch.begin()
+
+        batch.shader = if (dither) IngameRenderer.shaderBayer else null
+        if (dither) {
+            batch.shader.setUniformi("u_pattern", 1)
+            batch.shader.setUniformi("rnd", renderng.nextInt(8192), renderng.nextInt(8192))
+        }
+
         blendMul(batch)
         batch.draw(tex, 0f, 0f, App.scr.wf, App.scr.hf)