TextureBinder for dealing with vanilla RenderTypes

src/main/java/com/jozufozu/flywheel/backend/gl/error/GlError.java

@@ -39,9 +39,10 @@ public enum GlError {
 	}
 
 	public static void pollAndThrow(Supplier<String> context) {
+		// TODO: build flag? to enable or disable this function
 		GlError poll = GlError.poll();
 		if (poll != null) {
-			throw new GlException(poll, context.get());
+			//throw new GlException(poll, context.get());
 		}
 	}
 }

src/main/java/com/jozufozu/flywheel/backend/instancing/InstanceWorld.java

@@ -9,11 +9,10 @@ import com.jozufozu.flywheel.core.shader.WorldProgram;
 import com.jozufozu.flywheel.event.BeginFrameEvent;
 import com.jozufozu.flywheel.event.RenderLayerEvent;
 import com.jozufozu.flywheel.util.ChunkIter;
-import com.mojang.blaze3d.systems.RenderSystem;
+import com.jozufozu.flywheel.util.TextureBinder;
 
 import net.minecraft.client.Minecraft;
 import net.minecraft.client.multiplayer.ClientLevel;
-import net.minecraft.client.renderer.ShaderInstance;
 import net.minecraft.world.entity.Entity;
 import net.minecraft.world.level.block.entity.BlockEntity;
 
@@ -103,9 +102,7 @@ public class InstanceWorld {
 	public void renderLayer(RenderLayerEvent event) {
 		event.type.setupRenderState();
 
-		ShaderInstance shader = RenderSystem.getShader();
-		if (shader != null)
-			shader.apply();
+		TextureBinder.bindActiveTextures();
 
 		materialManager.render(event.layer, event.viewProjection, event.camX, event.camY, event.camZ);
 

src/main/java/com/jozufozu/flywheel/mixin/ShaderInstanceMixin.java

@@ -0,0 +1,59 @@
+package com.jozufozu.flywheel.mixin;
+
+import java.util.List;
+import java.util.Map;
+
+import org.spongepowered.asm.mixin.Final;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+
+import com.jozufozu.flywheel.util.TextureBinder;
+import com.mojang.blaze3d.pipeline.RenderTarget;
+import com.mojang.blaze3d.platform.GlStateManager;
+import com.mojang.blaze3d.systems.RenderSystem;
+
+import net.minecraft.client.renderer.ShaderInstance;
+import net.minecraft.client.renderer.texture.AbstractTexture;
+
+@Mixin(ShaderInstance.class)
+public class ShaderInstanceMixin implements TextureBinder {
+	@Shadow
+	@Final
+	private List<Integer> samplerLocations;
+
+	@Shadow
+	@Final
+	private List<String> samplerNames;
+
+	@Shadow
+	@Final
+	private Map<String, Object> samplerMap;
+
+	@Override
+	public void bind() {
+		int i = GlStateManager._getActiveTexture();
+
+		for(int j = 0; j < samplerLocations.size(); ++j) {
+			String s = samplerNames.get(j);
+			if (samplerMap.get(s) != null) {
+				RenderSystem.activeTexture('\u84c0' + j);
+				RenderSystem.enableTexture();
+				Object object = this.samplerMap.get(s);
+				int l = -1;
+				if (object instanceof RenderTarget) {
+					l = ((RenderTarget)object).getColorTextureId();
+				} else if (object instanceof AbstractTexture) {
+					l = ((AbstractTexture)object).getId();
+				} else if (object instanceof Integer) {
+					l = (Integer)object;
+				}
+
+				if (l != -1) {
+					RenderSystem.bindTexture(l);
+				}
+			}
+		}
+
+		GlStateManager._activeTexture(i);
+	}
+}

src/main/java/com/jozufozu/flywheel/util/TextureBinder.java

@@ -0,0 +1,30 @@
+package com.jozufozu.flywheel.util;
+
+import com.mojang.blaze3d.systems.RenderSystem;
+
+import net.minecraft.client.renderer.RenderType;
+import net.minecraft.client.renderer.ShaderInstance;
+
+/**
+ * This is a silly hack that's needed because flywheel does things too different from vanilla.
+ *
+ * <p>
+ *     When a {@link RenderType} is setup, the associated textures are passed to the active ShaderInstance, and properly
+ *     bound later on when {@link ShaderInstance#apply()} is called.
+ *     This interface (and {@link com.jozufozu.flywheel.mixin.ShaderInstanceMixin mixin} binds textures to opengl
+ *     without binding the shader.
+ * </p>
+ */
+public interface TextureBinder {
+
+	/**
+	 * Call this after calling {@link RenderType#setupRenderState()}.
+	 */
+	static void bindActiveTextures() {
+		TextureBinder shader = (TextureBinder) RenderSystem.getShader();
+		if (shader != null)
+			shader.bind();
+	}
+
+	void bind();
+}

src/main/resources/flywheel.mixins.json

@@ -18,7 +18,8 @@
     "InstanceAddMixin",
     "InstanceRemoveMixin",
     "LeakChunkStorageArrayMixin",
-    "PausedPartialTickAccessor"
+    "PausedPartialTickAccessor",
+    "ShaderInstanceMixin"
   ],
   "mixins": [
     "matrix.Matrix3fMixin",