A sample of what's to come

- Clean up texture binder stuff that's no longer needed
- Move all sampler binding to program link time
- Centralize sampler bindings/names to Samplers
- Move diffuse, light, and overlay textures into the api
- Add builder for context shader
- Fix generated_indirect -> generated_instancing

docs/shader-api/fragment.glsl

@@ -27,3 +27,7 @@ bool flw_discardPredicate(vec4 finalColor);
 // To be implemented by the context shader.
 void flw_beginFragment();
 void flw_endFragment();
+
+sampler2D flw_diffuseTex;
+sampler2D flw_overlayTex;
+sampler2D flw_lightTex;

src/main/java/com/jozufozu/flywheel/backend/compile/ContextShader.java

@@ -1,6 +1,48 @@
 package com.jozufozu.flywheel.backend.compile;
 
+import java.util.Objects;
+import java.util.function.Consumer;
+
+import org.jetbrains.annotations.Nullable;
+
+import com.jozufozu.flywheel.backend.gl.shader.GlProgram;
+
 import net.minecraft.resources.ResourceLocation;
 
-public record ContextShader(ResourceLocation vertexShader, ResourceLocation fragmentShader) {
+public record ContextShader(ResourceLocation vertexShader, ResourceLocation fragmentShader,
+							Consumer<GlProgram> onLink) {
+	public static Builder builder() {
+		return new Builder();
+	}
+
+	public static class Builder {
+		@Nullable
+		private ResourceLocation vertexShader;
+		@Nullable
+		private ResourceLocation fragmentShader;
+		@Nullable
+		private Consumer<GlProgram> onLink;
+
+		public Builder vertexShader(ResourceLocation shader) {
+			this.vertexShader = shader;
+			return this;
+		}
+
+		public Builder fragmentShader(ResourceLocation shader) {
+			this.fragmentShader = shader;
+			return this;
+		}
+
+		public Builder onLink(Consumer<GlProgram> onLink) {
+			this.onLink = onLink;
+			return this;
+		}
+
+		public ContextShader build() {
+			Objects.requireNonNull(vertexShader);
+			Objects.requireNonNull(fragmentShader);
+			Objects.requireNonNull(onLink);
+			return new ContextShader(vertexShader, fragmentShader, onLink);
+		}
+	}
 }

src/main/java/com/jozufozu/flywheel/backend/compile/ContextShaders.java

@@ -6,12 +6,27 @@ import com.jozufozu.flywheel.Flywheel;
 import com.jozufozu.flywheel.api.internal.InternalFlywheelApi;
 import com.jozufozu.flywheel.api.registry.Registry;
 import com.jozufozu.flywheel.api.visualization.VisualEmbedding;
+import com.jozufozu.flywheel.backend.engine.Samplers;
 
 public class ContextShaders {
 	public static final Registry<ContextShader> REGISTRY = InternalFlywheelApi.INSTANCE.createRegistry();
-	public static final ContextShader DEFAULT = REGISTRY.registerAndGet(new ContextShader(Flywheel.rl("internal/context/default.vert"), Flywheel.rl("internal/context/default.frag")));
-	public static final ContextShader CRUMBLING = REGISTRY.registerAndGet(new ContextShader(Flywheel.rl("internal/context/crumbling.vert"), Flywheel.rl("internal/context/crumbling.frag")));
-	public static final ContextShader EMBEDDED = REGISTRY.registerAndGet(new ContextShader(Flywheel.rl("internal/context/embedded.vert"), Flywheel.rl("internal/context/embedded.frag")));
+	public static final ContextShader DEFAULT = REGISTRY.registerAndGet(ContextShader.builder()
+			.vertexShader(Flywheel.rl("internal/context/default.vert"))
+			.fragmentShader(Flywheel.rl("internal/context/default.frag"))
+			.onLink($ -> {
+			})
+			.build());
+	public static final ContextShader CRUMBLING = REGISTRY.registerAndGet(ContextShader.builder()
+			.vertexShader(Flywheel.rl("internal/context/crumbling.vert"))
+			.fragmentShader(Flywheel.rl("internal/context/crumbling.frag"))
+			.onLink(program -> program.setSamplerBinding("_flw_crumblingTex", Samplers.CRUMBLING))
+			.build());
+	public static final ContextShader EMBEDDED = REGISTRY.registerAndGet(ContextShader.builder()
+			.vertexShader(Flywheel.rl("internal/context/embedded.vert"))
+			.fragmentShader(Flywheel.rl("internal/context/embedded.frag"))
+			.onLink($ -> {
+			})
+			.build());
 
 	public static ContextShader forEmbedding(@Nullable VisualEmbedding level) {
 		if (level == null) {

src/main/java/com/jozufozu/flywheel/backend/compile/Pipeline.java

@@ -1,8 +1,12 @@
 package com.jozufozu.flywheel.backend.compile;
 
 import java.util.Objects;
+import java.util.function.Consumer;
+
+import org.jetbrains.annotations.Nullable;
 
 import com.jozufozu.flywheel.api.instance.InstanceType;
+import com.jozufozu.flywheel.backend.gl.shader.GlProgram;
 import com.jozufozu.flywheel.backend.glsl.GlslVersion;
 import com.jozufozu.flywheel.backend.glsl.SourceComponent;
 
@@ -10,7 +14,8 @@ import net.minecraft.resources.ResourceLocation;
 
 public record Pipeline(GlslVersion glslVersion, ResourceLocation vertexMain, ResourceLocation fragmentMain,
 					   ResourceLocation vertexApiImpl, ResourceLocation fragmentApiImpl, InstanceAssembler assembler,
-					   String compilerMarker) {
+					   String compilerMarker, Consumer<GlProgram> onLink) {
+
 	@FunctionalInterface
 	public interface InstanceAssembler {
 		/**
@@ -29,13 +34,22 @@ public record Pipeline(GlslVersion glslVersion, ResourceLocation vertexMain, Res
 	}
 
 	public static class Builder {
+		@Nullable
 		private GlslVersion glslVersion;
+		@Nullable
 		private ResourceLocation vertexMain;
+		@Nullable
 		private ResourceLocation fragmentMain;
+		@Nullable
 		private ResourceLocation vertexApiImpl;
+		@Nullable
 		private ResourceLocation fragmentApiImpl;
+		@Nullable
 		private InstanceAssembler assembler;
+		@Nullable
 		private String compilerMarker;
+		@Nullable
+		private Consumer<GlProgram> onLink;
 
 		public Builder glslVersion(GlslVersion glslVersion) {
 			this.glslVersion = glslVersion;
@@ -72,6 +86,11 @@ public record Pipeline(GlslVersion glslVersion, ResourceLocation vertexMain, Res
 			return this;
 		}
 
+		public Builder onLink(Consumer<GlProgram> onLink) {
+			this.onLink = onLink;
+			return this;
+		}
+
 		public Pipeline build() {
 			Objects.requireNonNull(glslVersion);
 			Objects.requireNonNull(vertexMain);
@@ -80,7 +99,8 @@ public record Pipeline(GlslVersion glslVersion, ResourceLocation vertexMain, Res
 			Objects.requireNonNull(fragmentApiImpl);
 			Objects.requireNonNull(assembler);
 			Objects.requireNonNull(compilerMarker);
-			return new Pipeline(glslVersion, vertexMain, fragmentMain, vertexApiImpl, fragmentApiImpl, assembler, compilerMarker);
+			Objects.requireNonNull(onLink);
+			return new Pipeline(glslVersion, vertexMain, fragmentMain, vertexApiImpl, fragmentApiImpl, assembler, compilerMarker, onLink);
 		}
 	}
 }

src/main/java/com/jozufozu/flywheel/backend/compile/PipelineCompiler.java

@@ -5,6 +5,7 @@ import java.util.List;
 import com.jozufozu.flywheel.backend.InternalVertex;
 import com.jozufozu.flywheel.backend.compile.core.CompilationHarness;
 import com.jozufozu.flywheel.backend.compile.core.Compile;
+import com.jozufozu.flywheel.backend.engine.Samplers;
 import com.jozufozu.flywheel.backend.gl.shader.GlProgram;
 import com.jozufozu.flywheel.backend.gl.shader.ShaderType;
 import com.jozufozu.flywheel.backend.glsl.ShaderSources;
@@ -64,9 +65,14 @@ public class PipelineCompiler {
 
 					program.bind();
 
-					program.setSamplerBinding("_flw_diffuseTex", 0);
-					program.setSamplerBinding("_flw_overlayTex", 1);
-					program.setSamplerBinding("_flw_lightTex", 2);
+					program.setSamplerBinding("flw_diffuseTex", Samplers.DIFFUSE);
+					program.setSamplerBinding("flw_overlayTex", Samplers.OVERLAY);
+					program.setSamplerBinding("flw_lightTex", Samplers.LIGHT);
+					pipeline.onLink()
+							.accept(program);
+					key.contextShader()
+							.onLink()
+							.accept(program);
 
 					GlProgram.unbind();
 				})

src/main/java/com/jozufozu/flywheel/backend/compile/Pipelines.java

@@ -3,6 +3,7 @@ package com.jozufozu.flywheel.backend.compile;
 import com.jozufozu.flywheel.Flywheel;
 import com.jozufozu.flywheel.backend.compile.component.IndirectComponent;
 import com.jozufozu.flywheel.backend.compile.component.SamplerBufferComponent;
+import com.jozufozu.flywheel.backend.engine.Samplers;
 import com.jozufozu.flywheel.backend.glsl.GlslVersion;
 
 public final class Pipelines {
@@ -14,6 +15,7 @@ public final class Pipelines {
 			.vertexApiImpl(Flywheel.rl("internal/instancing/api_impl.vert"))
 			.fragmentApiImpl(Flywheel.rl("internal/instancing/api_impl.frag"))
 			.assembler(SamplerBufferComponent::create)
+			.onLink(program -> program.setSamplerBinding("_flw_instances", Samplers.INSTANCE_BUFFER))
 			.build();
 	public static final Pipeline INDIRECT = Pipeline.builder()
 			.compilerMarker("indirect")
@@ -23,5 +25,7 @@ public final class Pipelines {
 			.vertexApiImpl(Flywheel.rl("internal/indirect/api_impl.vert"))
 			.fragmentApiImpl(Flywheel.rl("internal/indirect/api_impl.frag"))
 			.assembler(IndirectComponent::create)
+			.onLink($ -> {
+			})
 			.build();
 }

src/main/java/com/jozufozu/flywheel/backend/compile/component/SamplerBufferComponent.java

@@ -53,7 +53,7 @@ public class SamplerBufferComponent implements SourceComponent {
 
 	@Override
 	public ResourceLocation name() {
-		return Flywheel.rl("generated_indirect");
+		return Flywheel.rl("generated_instancing");
 	}
 
 	@Override

src/main/java/com/jozufozu/flywheel/backend/engine/CommonCrumbling.java

@@ -3,13 +3,9 @@ package com.jozufozu.flywheel.backend.engine;
 import com.jozufozu.flywheel.api.material.Material;
 import com.jozufozu.flywheel.api.material.Transparency;
 import com.jozufozu.flywheel.api.material.WriteMask;
-import com.jozufozu.flywheel.backend.gl.GlTextureUnit;
 import com.jozufozu.flywheel.lib.material.CutoutShaders;
 import com.jozufozu.flywheel.lib.material.FogShaders;
 import com.jozufozu.flywheel.lib.material.SimpleMaterial;
-import com.mojang.blaze3d.systems.RenderSystem;
-
-import net.minecraft.client.Minecraft;
 
 public class CommonCrumbling {
 	public static void applyCrumblingProperties(SimpleMaterial.Builder crumblingMaterial, Material baseMaterial) {
@@ -23,17 +19,4 @@ public class CommonCrumbling {
 				.useLight(false)
 				.diffuse(false);
 	}
-
-	public static int getDiffuseTexture(Material material) {
-		return Minecraft.getInstance()
-				.getTextureManager()
-				.getTexture(material.texture())
-				.getId();
-	}
-
-	public static void setActiveAndBindForCrumbling(int diffuseTexture) {
-		GlTextureUnit.T1.makeActive();
-		RenderSystem.setShaderTexture(1, diffuseTexture);
-		RenderSystem.bindTexture(diffuseTexture);
-	}
 }

src/main/java/com/jozufozu/flywheel/backend/engine/MaterialRenderState.java

@@ -8,7 +8,6 @@ import com.jozufozu.flywheel.api.material.DepthTest;
 import com.jozufozu.flywheel.api.material.Material;
 import com.jozufozu.flywheel.api.material.Transparency;
 import com.jozufozu.flywheel.api.material.WriteMask;
-import com.jozufozu.flywheel.backend.gl.GlTextureUnit;
 import com.mojang.blaze3d.platform.GlStateManager;
 import com.mojang.blaze3d.systems.RenderSystem;
 
@@ -38,7 +37,7 @@ public final class MaterialRenderState {
 	}
 
 	private static void setupTexture(Material material) {
-		GlTextureUnit.T0.makeActive();
+		Samplers.DIFFUSE.makeActive();
 		AbstractTexture texture = Minecraft.getInstance()
 				.getTextureManager()
 				.getTexture(material.texture());
@@ -150,7 +149,7 @@ public final class MaterialRenderState {
 	}
 
 	private static void resetTexture() {
-		GlTextureUnit.T0.makeActive();
+		Samplers.DIFFUSE.makeActive();
 		RenderSystem.setShaderTexture(0, 0);
 	}
 

src/main/java/com/jozufozu/flywheel/backend/engine/Samplers.java

@@ -0,0 +1,11 @@
+package com.jozufozu.flywheel.backend.engine;
+
+import com.jozufozu.flywheel.backend.gl.GlTextureUnit;
+
+public class Samplers {
+	public static final GlTextureUnit DIFFUSE = GlTextureUnit.T0;
+	public static final GlTextureUnit OVERLAY = GlTextureUnit.T1;
+	public static final GlTextureUnit LIGHT = GlTextureUnit.T2;
+	public static final GlTextureUnit CRUMBLING = GlTextureUnit.T3;
+	public static final GlTextureUnit INSTANCE_BUFFER = GlTextureUnit.T4;
+}

src/main/java/com/jozufozu/flywheel/backend/engine/TextureBinder.java

@@ -1,62 +1,24 @@
 package com.jozufozu.flywheel.backend.engine;
 
-import static org.lwjgl.opengl.GL13.GL_TEXTURE0;
-
-import com.jozufozu.flywheel.backend.gl.GlTextureUnit;
 import com.mojang.blaze3d.systems.RenderSystem;
 
-import it.unimi.dsi.fastutil.ints.Int2IntArrayMap;
-import it.unimi.dsi.fastutil.ints.Int2IntMap;
 import net.minecraft.client.Minecraft;
 import net.minecraft.resources.ResourceLocation;
 
 public class TextureBinder {
-	// TODO: some kind of cache eviction when the program changes
-	//  so we don't always reset and bind the light and overlay textures?
-	private static final Int2IntMap texturesToSamplerUnits = new Int2IntArrayMap();
-	// 0 is reserved for diffuse
-	// 1 is overlay
-	// 2 is light
-	// 3 is the instance buffer
-	// 4..n are for whatever else the context needs
-	private static final int baseSamplerUnit = 4;
-	private static int nextSamplerUnit = baseSamplerUnit;
-
-	/**
-	 * Binds the given texture to the next available texture unit, returning the unit it was bound to.
-	 *
-	 * @param id The id of the texture to bind.
-	 * @return The texture unit the texture was bound to.
-	 */
-	public static int bindTexture(int id) {
-		return texturesToSamplerUnits.computeIfAbsent(id, i -> {
-			int unit = nextSamplerUnit++;
-			RenderSystem.activeTexture(GL_TEXTURE0 + unit);
-			RenderSystem.bindTexture(i);
-			return unit;
-		});
-	}
-
-	public static void resetTextureBindings() {
-		nextSamplerUnit = baseSamplerUnit;
-
-		for (Int2IntMap.Entry entry : texturesToSamplerUnits.int2IntEntrySet()) {
-			RenderSystem.activeTexture(GL_TEXTURE0 + entry.getIntValue());
-			RenderSystem.bindTexture(0);
-		}
-
-		texturesToSamplerUnits.clear();
+	public static void bind(ResourceLocation resourceLocation) {
+		RenderSystem.bindTexture(byName(resourceLocation));
 	}
 
 	public static void bindLightAndOverlay() {
 		var gameRenderer = Minecraft.getInstance().gameRenderer;
 
-		GlTextureUnit.T1.makeActive();
+		Samplers.OVERLAY.makeActive();
 		gameRenderer.overlayTexture()
 				.setupOverlayColor();
 		RenderSystem.bindTexture(RenderSystem.getShaderTexture(1));
 
-		GlTextureUnit.T2.makeActive();
+		Samplers.LIGHT.makeActive();
 		gameRenderer.lightTexture()
 				.turnOnLightLayer();
 		RenderSystem.bindTexture(RenderSystem.getShaderTexture(2));

src/main/java/com/jozufozu/flywheel/backend/engine/indirect/IndirectCullingGroup.java

@@ -29,7 +29,6 @@ import com.jozufozu.flywheel.backend.compile.ContextShaders;
 import com.jozufozu.flywheel.backend.compile.IndirectPrograms;
 import com.jozufozu.flywheel.backend.engine.MaterialRenderState;
 import com.jozufozu.flywheel.backend.engine.MeshPool;
-import com.jozufozu.flywheel.backend.engine.TextureBinder;
 import com.jozufozu.flywheel.backend.engine.uniform.Uniforms;
 import com.jozufozu.flywheel.backend.gl.Driver;
 import com.jozufozu.flywheel.backend.gl.GlCompat;
@@ -226,7 +225,6 @@ public class IndirectCullingGroup<I extends Instance> {
 			MaterialRenderState.setup(multiDraw.material);
 
 			multiDraw.submit();
-			TextureBinder.resetTextureBindings();
 		}
 	}
 

src/main/java/com/jozufozu/flywheel/backend/engine/indirect/IndirectDrawManager.java

@@ -26,6 +26,7 @@ import com.jozufozu.flywheel.backend.engine.InstancerKey;
 import com.jozufozu.flywheel.backend.engine.InstancerStorage;
 import com.jozufozu.flywheel.backend.engine.MaterialRenderState;
 import com.jozufozu.flywheel.backend.engine.MeshPool;
+import com.jozufozu.flywheel.backend.engine.Samplers;
 import com.jozufozu.flywheel.backend.engine.TextureBinder;
 import com.jozufozu.flywheel.backend.engine.uniform.Uniforms;
 import com.jozufozu.flywheel.backend.gl.GlStateTracker;
@@ -167,8 +168,11 @@ public class IndirectDrawManager extends InstancerStorage<IndirectInstancer<?>>
 				var program = cullingGroups.get(instanceTypeEntry.getKey())
 						.bindWithContextShader(ContextShaders.CRUMBLING);
 
+				program.setSamplerBinding("crumblingTex", Samplers.CRUMBLING);
+
 				for (var progressEntry : byProgress.int2ObjectEntrySet()) {
-					program.setTexture("crumblingTex", TextureBinder.byName(ModelBakery.BREAKING_LOCATIONS.get(progressEntry.getIntKey())));
+					Samplers.CRUMBLING.makeActive();
+					TextureBinder.bind(ModelBakery.BREAKING_LOCATIONS.get(progressEntry.getIntKey()));
 
 					for (var instanceHandlePair : progressEntry.getValue()) {
 						IndirectInstancer<?> instancer = instanceHandlePair.first();
@@ -190,7 +194,6 @@ public class IndirectDrawManager extends InstancerStorage<IndirectInstancer<?>>
 						}
 					}
 
-					TextureBinder.resetTextureBindings();
 				}
 			}
 

src/main/java/com/jozufozu/flywheel/backend/engine/instancing/InstancedDrawManager.java

@@ -28,10 +28,10 @@ import com.jozufozu.flywheel.backend.engine.InstancerStorage;
 import com.jozufozu.flywheel.backend.engine.MaterialEncoder;
 import com.jozufozu.flywheel.backend.engine.MaterialRenderState;
 import com.jozufozu.flywheel.backend.engine.MeshPool;
+import com.jozufozu.flywheel.backend.engine.Samplers;
 import com.jozufozu.flywheel.backend.engine.TextureBinder;
 import com.jozufozu.flywheel.backend.engine.uniform.Uniforms;
 import com.jozufozu.flywheel.backend.gl.GlStateTracker;
-import com.jozufozu.flywheel.backend.gl.GlTextureUnit;
 import com.jozufozu.flywheel.backend.gl.TextureBuffer;
 import com.jozufozu.flywheel.backend.gl.array.GlVertexArray;
 import com.jozufozu.flywheel.backend.gl.shader.GlProgram;
@@ -140,14 +140,11 @@ public class InstancedDrawManager extends InstancerStorage<InstancedInstancer<?>
 
 			MaterialRenderState.setup(material);
 
-			GlTextureUnit.T3.makeActive();
-
-			program.setSamplerBinding("_flw_instances", 3);
+			Samplers.INSTANCE_BUFFER.makeActive();
 
 			for (var drawCall : drawCalls) {
 				drawCall.render(instanceTexture);
 			}
-			TextureBinder.resetTextureBindings();
 		}
 
 		MaterialRenderState.reset();
@@ -218,16 +215,14 @@ public class InstancedDrawManager extends InstancerStorage<InstancedInstancer<?>
 						continue;
 					}
 
-					program.setTexture("crumblingTex", TextureBinder.byName(ModelBakery.BREAKING_LOCATIONS.get(progressEntry.getIntKey())));
+					Samplers.CRUMBLING.makeActive();
+					TextureBinder.bind(ModelBakery.BREAKING_LOCATIONS.get(progressEntry.getIntKey()));
 
-					GlTextureUnit.T3.makeActive();
-					program.setSamplerBinding("_flw_instances", 3);
+					Samplers.INSTANCE_BUFFER.makeActive();
 
 					for (Consumer<TextureBuffer> drawCall : drawCalls) {
 						drawCall.accept(instanceTexture);
 					}
-
-					TextureBinder.resetTextureBindings();
 				}
 			}
 

src/main/java/com/jozufozu/flywheel/backend/gl/shader/GlProgram.java

@@ -18,8 +18,8 @@ import org.joml.Matrix3fc;
 import org.joml.Matrix4fc;
 import org.slf4j.Logger;
 
-import com.jozufozu.flywheel.backend.engine.TextureBinder;
 import com.jozufozu.flywheel.backend.gl.GlObject;
+import com.jozufozu.flywheel.backend.gl.GlTextureUnit;
 import com.mojang.blaze3d.shaders.ProgramManager;
 import com.mojang.logging.LogUtils;
 
@@ -43,18 +43,6 @@ public class GlProgram extends GlObject {
 		ProgramManager.glUseProgram(0);
 	}
 
-	public void setTexture(String glslName, int texture) {
-		int uniform = getUniformLocation(glslName);
-
-		if (uniform < 0) {
-			return;
-		}
-
-		int binding = TextureBinder.bindTexture(texture);
-
-		glUniform1i(uniform, binding);
-	}
-
 	public void setFloat(String glslName, float value) {
 		int uniform = getUniformLocation(glslName);
 
@@ -148,6 +136,10 @@ public class GlProgram extends GlObject {
 	 * @param name    The name of the sampler uniform.
 	 * @param binding The index of the texture unit.
 	 */
+	public void setSamplerBinding(String name, GlTextureUnit binding) {
+		setSamplerBinding(name, binding.number);
+	}
+
 	public void setSamplerBinding(String name, int binding) {
 		int samplerUniform = getUniformLocation(name);
 

src/main/resources/assets/flywheel/flywheel/internal/common.frag

@@ -6,16 +6,12 @@
 layout (depth_greater) out float gl_FragDepth;
 #endif
 
-uniform sampler2D _flw_diffuseTex;
-uniform sampler2D _flw_overlayTex;
-uniform sampler2D _flw_lightTex;
-
 out vec4 _flw_outputColor;
 
 in vec4 _flw_debugColor;
 
 void _flw_main() {
-    flw_sampleColor = texture(_flw_diffuseTex, flw_vertexTexCoord);
+    flw_sampleColor = texture(flw_diffuseTex, flw_vertexTexCoord);
     flw_fragColor = flw_vertexColor * flw_sampleColor;
     flw_fragOverlay = flw_vertexOverlay;
     flw_fragLight = flw_vertexLight;
@@ -40,12 +36,12 @@ void _flw_main() {
         // Need to clamp the overlay texture coords to sane coordinates because integer vertex attributes explode on
         // some drivers for some draw calls. This should only effect instances that don't write to overlay, but
         // the internal vertex format is unfortunately subject to these issues.
-        vec4 overlayColor = texelFetch(_flw_overlayTex, clamp(flw_fragOverlay, 0, 10), 0);
+        vec4 overlayColor = texelFetch(flw_overlayTex, clamp(flw_fragOverlay, 0, 10), 0);
         color.rgb = mix(overlayColor.rgb, color.rgb, overlayColor.a);
     }
 
     if (flw_material.useLight) {
-        vec4 lightColor = texture(_flw_lightTex, (flw_fragLight * 15.0 + 0.5) / 16.0);
+        vec4 lightColor = texture(flw_lightTex, (flw_fragLight * 15.0 + 0.5) / 16.0);
         color *= lightColor;
     }
 

src/main/resources/assets/flywheel/flywheel/internal/common_api_impl.frag

@@ -19,3 +19,7 @@ bool flw_fragDiffuse;
 vec4 flw_fragColor;
 ivec2 flw_fragOverlay;
 vec2 flw_fragLight;
+
+uniform sampler2D flw_diffuseTex;
+uniform sampler2D flw_overlayTex;
+uniform sampler2D flw_lightTex;

src/main/resources/assets/flywheel/flywheel/internal/context/crumbling.frag

@@ -1,4 +1,4 @@
-uniform sampler2D crumblingTex;
+uniform sampler2D _flw_crumblingTex;
 
 in vec2 crumblingTexCoord;
 
@@ -8,7 +8,7 @@ void flw_beginFragment() {
 }
 
 void flw_endFragment() {
-    crumblingSampleColor = texture(crumblingTex, crumblingTexCoord);
+    crumblingSampleColor = texture(_flw_crumblingTex, crumblingTexCoord);
 
     // Make the crumbling overlay transparent when the fragment color after the material shader is transparent.
     flw_fragColor.rgb = crumblingSampleColor.rgb;