Advanced Shader Techniques

Advanced Shader Techniques

This guide covers advanced shader development techniques in Minecraft 26.1, including custom pipeline construction, post-processing effects, and performance optimization strategies.

Custom Shader Pipeline Construction

Pipeline Builder Pattern

Minecraft 26.1 uses a fluent builder pattern for shader pipeline configuration:

com.mojang.blaze3d.pipeline.RenderPipeline

public static RenderPipeline.Builder builder(final RenderPipeline.Snippet... snippets) {
    RenderPipeline.Builder builder = new RenderPipeline.Builder();
    for (RenderPipeline.Snippet snippet : snippets) {
        builder.withSnippet(snippet);
    }
    return builder;
}

// Example: Building custom pipeline
public class CustomPipelineBuilder {
    public static RenderPipeline createGlowPipeline() {
        return RenderPipeline.builder()
            .withSnippet(createVertexSnippet())
            .withSnippet(createFragmentSnippet())
            .withTarget(RenderTarget.COLOR)
            .withBlendMode(BlendMode.ADD)
            .build();
    }

    private static RenderPipeline.Snippet createVertexSnippet() {
        return new RenderPipeline.Snippet() {
            @Override
            public void apply(RenderPipeline.Builder builder) {
                builder.vertexShader("custom_vertex.glsl")
                       .attribute("position", VertexFormat.Element.POSITION)
                       .attribute("color", VertexFormat.Element.COLOR)
                       .uniform("modelViewMatrix", Matrix4f.class)
                       .uniform("projectionMatrix", Matrix4f.class);
            }
        };
    }
}

Multi-pass Rendering Systems

Create complex multi-pass effects using the post-processing chain system:

net.minecraft.client.renderer.PostChain

public class PostChain {
    private final List<PostPass> passes = new ArrayList<>();
    private final Map<String, RenderTarget> targets = new HashMap<>();

    public void addPass(String name, ResourceLocation shader,
                        String... inputTargets) {
        PostPass pass = new PostPass(shader, inputTargets);
        passes.add(pass);

        // Create output target if needed
        if (!targets.containsKey(name + "_output")) {
            RenderTarget target = createRenderTarget();
            targets.put(name + "_output", target);
            pass.setOutputTarget(name + "_output");
        }
    }

    public void process(float partialTick) {
        for (PostPass pass : passes) {
            pass.process(partialTick);

            // Chain output to next input if needed
            chainTargets(pass);
        }
    }

    private void chainTargets(PostPass pass) {
        String outputName = pass.getOutputTarget();
        if (outputName != null && targets.containsKey(outputName)) {
            RenderTarget output = targets.get(outputName);
            // Set as input for next pass
            for (PostPass nextPass : passes) {
                if (nextPass != pass && nextPass.needsInput()) {
                    nextPass.setInputTarget(outputName);
                }
            }
        }
    }
}

Advanced Shader Effects

Custom Lighting Models

Implement advanced lighting systems beyond Minecraft’s default:

// Example: Custom PBR lighting shader
public class PBRLightingSystem {
    public static RenderType createPBRRenderType() {
        return RenderType.builder()
            .setupRenderState(state -> {
                RenderSystem.enableBlend();
                RenderSystem.blendFunc(SourceFactor.SRC_ALPHA,
                                     DestFactor.ONE_MINUS_SRC_ALPHA);
            })
            .shader(new ShaderInstance() {
                @Override
                public void apply(PoseStack poseStack, MultiBufferSource buffer) {
                    // PBR uniform setup
                    uniform("albedo", getAlbedoTexture());
                    uniform("normal", getNormalTexture());
                    uniform("roughness", getRoughnessTexture());
                    uniform("metallic", getMetallicTexture());
                    uniform("ao", getAmbientOcclusionTexture());

                    // Environment maps
                    uniform("irradianceMap", getIrradianceMap());
                    uniform("prefilterMap", getPrefilterMap());
                    uniform("brdfLUT", getBRDFLUT());

                    // Lighting parameters
                    uniform("lightPositions", getLightPositions());
                    uniform("lightColors", getLightColors());
                    uniform("lightIntensities", getLightIntensities());
                }
            })
            .build();
    }
}

Time-Based Animations

Create smooth time-based shader animations:

// Example: Animated shader system
public class AnimatedShaderRenderer {
    private final ShaderInstance animatedShader;
    private final UniformFloat timeUniform;
    private final UniformFloat speedUniform;

    public AnimatedShaderRenderer() {
        this.animatedShader = loadAnimatedShader();
        this.timeUniform = animatedShader.getUniform("u_time");
        this.speedUniform = animatedShader.getUniform("u_speed");

        speedUniform.set(1.0f);
    }

    public void render(PoseStack poseStack, float partialTick) {
        RenderSystem.setShader(() -> animatedShader);

        // Update time uniform for animation
        float time = (Minecraft.getInstance().level.getGameTime() + partialTick) / 20.0f;
        timeUniform.set(time);

        // Render with animation
        renderGeometry(poseStack);
    }

    public void setAnimationSpeed(float speed) {
        speedUniform.set(speed);
    }

    // GLSL Animation Example:
    /*
    uniform float u_time;
    uniform float u_speed;

    vec3 animatedPosition(vec3 position) {
        float wave = sin(position.x * 2.0 + u_time * u_speed) * 0.1;
        return position + vec3(0.0, wave, 0.0);
    }

    vec4 animatedColor(vec4 baseColor) {
        float pulse = sin(u_time * u_speed * 2.0) * 0.5 + 0.5;
        return mix(baseColor, vec4(1.0), pulse * 0.3);
    }
    */
}

Procedural Textures

Generate textures procedurally in shaders:

// Example: Procedural texture shader
public class ProceduralTextureShader {
    public static RenderType createProceduralRenderType() {
        return RenderType.builder()
            .shader(new ProceduralShader())
            .texture("u_noise", generateNoiseTexture())
            .build();
    }

    private static class ProceduralShader extends ShaderInstance {
        @Override
        public void apply(PoseStack poseStack, MultiBufferSource buffer) {
            uniform("u_resolution", new Vector2f(1920.0f, 1080.0f));
            uniform("u_time", getGameTime());
            uniform("u_scale", 4.0f);
        }
    }

    // GLSL Procedural Texture Example:
    /*
    uniform vec2 u_resolution;
    uniform float u_time;
    uniform float u_scale;
    uniform sampler2D u_noise;

    vec4 proceduralColor(vec2 uv) {
        // Noise-based texture generation
        vec2 noiseUV = uv * u_scale;
        float noise = texture(u_noise, noiseUV + u_time * 0.1).r;

        // Create patterns using mathematical functions
        float pattern1 = sin(uv.x * 10.0 + u_time) * cos(uv.y * 10.0 + u_time);
        float pattern2 = length(uv - 0.5) - 0.3 + noise * 0.1;

        // Combine patterns
        vec3 color = vec3(0.0);
        color.r = pattern1 * noise;
        color.g = pattern2 * noise;
        color.b = (pattern1 + pattern2) * 0.5 * noise;

        return vec4(color, 1.0);
    }
    */
}

Post-Processing Effects

Bloom Effect

Implement bloom post-processing for glowing effects:

// Example: Bloom post-processing
public class BloomPostProcessor {
    private final PostChain bloomChain;
    private final RenderTarget[] bloomTargets;
    private final float[] bloomThresholds = {1.0f, 0.8f, 0.6f, 0.4f};

    public BloomPostProcessor(int width, int height) {
        this.bloomTargets = new RenderTarget[4];
        for (int i = 0; i < bloomTargets.length; i++) {
            bloomTargets[i] = createRenderTarget(width >> i, height >> i);
        }

        this.bloomChain = createBloomChain();
    }

    private PostChain createBloomChain() {
        PostChain chain = new PostChain();

        // Bright pass - extract bright areas
        chain.addPass("bright", BRIGHT_PASS_SHADER, "scene");

        // Gaussian blur passes (horizontal + vertical)
        for (int i = 0; i < bloomTargets.length; i++) {
            chain.addPass("blur_h_" + i, BLUR_HORIZONTAL_SHADER,
                         "bright_output", "blur_v_" + (i - 1) + "_output");
            chain.addPass("blur_v_" + i, BLUR_VERTICAL_SHADER,
                         "blur_h_" + i + "_output");
        }

        // Bloom combine
        chain.addPass("combine", BLOOM_COMBINE_SHADER, "scene",
                     "blur_v_0_output", "blur_v_1_output",
                     "blur_v_2_output", "blur_v_3_output");

        return chain;
    }

    public void process(RenderTarget sceneTarget, float partialTick) {
        // Bind scene as input
        bloomChain.setInput("scene", sceneTarget);

        // Process bloom chain
        bloomChain.process(partialTick);
    }

    // GLSL Bright Pass Shader:
    /*
    uniform sampler2D u_texture;
    uniform float u_threshold;

    out vec4 fragColor;

    void main() {
        vec2 uv = gl_FragCoord.xy / u_resolution;
        vec4 color = texture(u_texture, uv);

        // Extract bright areas
        float brightness = dot(color.rgb, vec3(0.2126, 0.7152, 0.0722));
        if (brightness < u_threshold) {
            discard;
        }

        fragColor = color;
    }
    */

    // GLSL Bloom Combine Shader:
    /*
    uniform sampler2D u_scene;
    uniform sampler2D u_bloom0;
    uniform sampler2D u_bloom1;
    uniform sampler2D u_bloom2;
    uniform sampler2D u_bloom3;
    uniform float u_bloomIntensity;

    out vec4 fragColor;

    void main() {
        vec2 uv = gl_FragCoord.xy / u_resolution;
        vec4 sceneColor = texture(u_scene, uv);

        // Sample bloom at different scales
        vec4 bloomColor = vec4(0.0);
        bloomColor += texture(u_bloom0, uv) * 0.5;
        bloomColor += texture(u_bloom1, uv) * 0.25;
        bloomColor += texture(u_bloom2, uv) * 0.15;
        bloomColor += texture(u_bloom3, uv) * 0.1;

        // Combine scene with bloom
        fragColor = sceneColor + bloomColor * u_bloomIntensity;
    }
    */
}

Motion Blur

Create motion blur for fast-moving objects:

// Example: Motion blur system
public class MotionBlurProcessor {
    private final RenderTarget[] historyBuffers = new RenderTarget[4];
    private int currentBuffer = 0;

    public MotionBlurProcessor(int width, int height) {
        for (int i = 0; i < historyBuffers.length; i++) {
            historyBuffers[i] = createRenderTarget(width, height);
        }
    }

    public void process(RenderTarget currentFrame, Matrix4f viewProjection,
                        Matrix4f previousViewProjection) {
        // Store current frame in history
        copyFramebuffer(currentFrame, historyBuffers[currentBuffer]);

        // Apply motion blur shader
        RenderSystem.setShader(() -> new MotionBlurShader());

        // Set shader uniforms
        uniform("u_currentFrame", currentFrame);
        uniform("u_velocity", calculateVelocityBuffer(viewProjection, previousViewProjection));

        // Sample history for blur
        for (int i = 0; i < historyBuffers.length; i++) {
            int bufferIndex = (currentBuffer - i + historyBuffers.length) % historyBuffers.length;
            uniform("u_history" + i, historyBuffers[bufferIndex]);
            uniform("u_weight" + i, calculateWeight(i));
        }

        // Render motion blur
        renderFullscreenQuad();

        currentBuffer = (currentBuffer + 1) % historyBuffers.length;
    }

    // GLSL Motion Blur Shader:
    /*
    uniform sampler2D u_currentFrame;
    uniform sampler2D u_velocity;
    uniform sampler2D u_history0;
    uniform sampler2D u_history1;
    uniform sampler2D u_history2;
    uniform sampler2D u_history3;
    uniform float u_weight0;
    uniform float u_weight1;
    uniform float u_weight2;
    uniform float u_weight3;

    out vec4 fragColor;

    void main() {
        vec2 uv = gl_FragCoord.xy / u_resolution;
        vec2 velocity = texture(u_velocity, uv).rg;

        // Sample history along velocity vector
        vec4 color = texture(u_currentFrame, uv);
        color += texture(u_history0, uv + velocity) * u_weight0;
        color += texture(u_history1, uv + velocity * 2.0) * u_weight1;
        color += texture(u_history2, uv + velocity * 3.0) * u_weight2;
        color += texture(u_history3, uv + velocity * 4.0) * u_weight3;

        fragColor = color / (1.0 + u_weight0 + u_weight1 + u_weight2 + u_weight3);
    }
    */
}

Performance Optimization

Shader Compilation and Caching

Optimize shader loading with intelligent caching:

// Example: Shader caching system
public class ShaderCache {
    private final Map<String, CompiledShader> shaderCache = new ConcurrentHashMap<>();
    private final Map<String, Long> lastModified = new ConcurrentHashMap<>();

    public ShaderInstance getOrCreateShader(String name, String vertexSource,
                                            String fragmentSource) {
        CompiledShader cached = shaderCache.get(name);

        if (cached != null && isUpToDate(name, vertexSource, fragmentSource)) {
            return cached.getInstance();
        }

        // Compile new shader
        CompiledShader shader = compileShader(name, vertexSource, fragmentSource);
        shaderCache.put(name, shader);

        return shader.getInstance();
    }

    private CompiledShader compileShader(String name, String vertexSource,
                                        String fragmentSource) {
        // Preprocess shaders (includes, macros)
        String processedVertex = preprocessShader(vertexSource);
        String processedFragment = preprocessShader(fragmentSource);

        // Compile with error handling
        try {
            ShaderInstance instance = new ShaderInstance(processedVertex, processedFragment);
            return new CompiledShader(instance, System.currentTimeMillis());
        } catch (ShaderCompilationException e) {
            LOGGER.error("Failed to compile shader: " + name, e);
            return getFallbackShader();
        }
    }

    private boolean isUpToDate(String name, String vertexSource, String fragmentSource) {
        CompiledShader cached = shaderCache.get(name);
        if (cached == null) return false;

        // Check if source files have been modified
        long currentTime = getLastModifiedTime(name);
        return cached.getTimestamp() >= currentTime;
    }

    private static class CompiledShader {
        private final ShaderInstance instance;
        private final long timestamp;

        CompiledShader(ShaderInstance instance, long timestamp) {
            this.instance = instance;
            this.timestamp = timestamp;
        }

        ShaderInstance getInstance() {
            return instance;
        }

        long getTimestamp() {
            return timestamp;
        }
    }
}

Conditional Rendering

Use shader variants for different scenarios:

// Example: Shader variant system
public class ShaderVariantManager {
    private final Map<String, Map<String, ShaderInstance>> variants = new HashMap<>();

    public ShaderInstance getVariant(String baseName, String... defines) {
        String variantKey = String.join("_", defines);

        return variants.computeIfAbsent(baseName, k -> new HashMap<>())
            .computeIfAbsent(variantKey, k -> compileVariant(baseName, defines));
    }

    private ShaderInstance compileVariant(String baseName, String[] defines) {
        String vertexSource = loadShaderSource(baseName + ".vert");
        String fragmentSource = loadShaderSource(baseName + ".frag");

        // Add defines to source
        StringBuilder defineBlock = new StringBuilder();
        for (String define : defines) {
            defineBlock.append("#define ").append(define).append("\n");
        }

        // Insert defines at beginning of shaders
        vertexSource = defineBlock.toString() + vertexSource;
        fragmentSource = defineBlock.toString() + fragmentSource;

        return new ShaderInstance(vertexSource, fragmentSource);
    }

    // Usage examples:
    public ShaderInstance getLitShader() {
        return getVariant("base_shader", "LIGHTING_ENABLED");
    }

    public ShaderInstance getUnlitShader() {
        return getVariant("base_shader");
    }

    public ShaderInstance getShadowCasterShader() {
        return getVariant("base_shader", "SHADOW_CASTER", "NO_LIGHTING");
    }

    // GLSL Example with conditionals:
    /*
    #ifdef LIGHTING_ENABLED
    vec3 applyLighting(vec3 baseColor, vec3 normal, vec3 lightDir) {
        float ndotl = max(dot(normal, lightDir), 0.0);
        return baseColor * ndotl;
    }
    #else
    vec3 applyLighting(vec3 baseColor, vec3 normal, vec3 lightDir) {
        return baseColor;
    }
    #endif

    #ifdef SHADOW_CASTER
    void main() {
        // Only output depth for shadow mapping
        gl_FragDepth = gl_FragCoord.z;
    }
    #else
    void main() {
        vec3 color = texture(u_albedo, v_uv).rgb;
        #ifdef LIGHTING_ENABLED
        color = applyLighting(color, v_normal, v_lightDir);
        #endif
        fragColor = vec4(color, 1.0);
    }
    #endif
    */
}

Uniform Buffer Optimization

Use uniform buffers for efficient data transfer:

// Example: Uniform buffer optimization
public class UniformBufferManager {
    private final DynamicUniformStorage uniformStorage;
    private final Map<String, Integer> uniformOffsets = new HashMap<>();

    public UniformBufferManager() {
        this.uniformStorage = new DynamicUniformStorage("GlobalUniforms", 64 * 1024);
    }

    public void updateGlobalUniforms(GlobalUniformData data) {
        int offset = 0;

        // Matrices
        offset = writeMatrix4(data.viewMatrix, offset);
        offset = writeMatrix4(data.projectionMatrix, offset);
        offset = writeMatrix4(data.viewProjectionMatrix, offset);

        // Lighting data
        offset = writeVector3Array(data.lightPositions, offset);
        offset = writeVector3Array(data.lightColors, offset);
        offset = writeFloatArray(data.lightIntensities, offset);

        // Time data
        offset = writeFloat(data.time, offset);
        offset = writeFloat(data.deltaTime, offset);

        // Update uniform buffer
        uniformStorage.flush();
    }

    public void bindUniformBuffer() {
        uniformStorage.bind(0);
    }

    // GLSL Uniform Buffer Layout:
    /*
    layout(std140, binding = 0) uniform GlobalUniforms {
        mat4 u_viewMatrix;
        mat4 u_projectionMatrix;
        mat4 u_viewProjectionMatrix;

        vec3 u_lightPositions[16];
        vec3 u_lightColors[16];
        float u_lightIntensities[16];

        float u_time;
        float u_deltaTime;
    };
    */
}

Advanced Debugging Tools

Shader Debugging

Create tools for debugging shader issues:

// Example: Shader debugging utilities
public class ShaderDebugger {
    private final Map<String, RenderTarget> debugTargets = new HashMap<>();

    public void enableDebugMode(String name) {
        // Create debug render target for intermediate results
        debugTargets.put(name, createDebugRenderTarget());
    }

    public void captureIntermediateResult(String name, String uniformName) {
        if (debugTargets.containsKey(name)) {
            // Capture current framebuffer state
            RenderTarget target = debugTargets.get(name);
            copyCurrentFramebuffer(target);

            // Save to disk for analysis
            saveTextureToFile(target.getTexture(), "debug_" + name + ".png");
        }
    }

    public void visualizeNormals(PoseStack poseStack) {
        RenderSystem.setShader(() -> new NormalVisualizationShader());

        // Render normals as colored lines
        for (Vertex vertex : getVertices()) {
            Vector3f normal = vertex.getNormal();
            Vector3f position = vertex.getPosition();

            renderNormalLine(position, normal);
        }
    }

    // GLSL Normal Visualization Shader:
    /*
    in vec3 v_position;
    in vec3 v_normal;

    out vec4 fragColor;

    void main() {
        // Map normals to colors for visualization
        vec3 color = (v_normal + 1.0) * 0.5;
        fragColor = vec4(color, 1.0);
    }
    */
}

Performance Profiling

Profile shader performance:

// Example: Shader performance profiler
public class ShaderProfiler {
    private final Map<String, Long> shaderTimes = new HashMap<>();
    private final Map<String, Integer> shaderCallCounts = new HashMap<>();

    public void beginShaderProfiling(String shaderName) {
        shaderTimes.put(shaderName, Blaze3D.getTime());
    }

    public void endShaderProfiling(String shaderName) {
        long startTime = shaderTimes.get(shaderName);
        long endTime = Blaze3D.getTime();
        long duration = endTime - startTime;

        shaderCallCounts.merge(shaderName, 1, Integer::sum);
        shaderTimes.merge(shaderName, duration, Long::sum);
    }

    public void printProfilingResults() {
        System.out.println("=== Shader Performance ===");
        shaderTimes.forEach((name, totalTime) -> {
            int callCount = shaderCallCounts.get(name);
            long averageTime = totalTime / callCount;

            System.out.printf("%s: %.2f ms avg, %d calls%n",
                            name, averageTime / 1_000_000.0, callCount);
        });
    }
}

Best Practices

Shader Development Guidelines

1. Profile before optimizing - measure actual bottlenecks
2. Use conditionals sparingly - they can cause thread divergence
3. Minimize texture lookups - they’re expensive operations
4. Batch uniform updates - update multiple uniforms together
5. Cache compiled shaders - avoid recompilation costs

Performance Considerations

// ❌ WRONG - Expensive per-fragment operations
void main() {
    for (int i = 0; i < 100; i++) {
        color += texture(u_texture, uv + randomOffset(i));
    }
}

// ✅ CORRECT - Optimized sampling
void main() {
    // Use pre-blurred textures or fewer samples
    color = texture(u_blurredTexture, uv);
}

Common Pitfalls

1. Uniform Value Leaks: Forgetting to reset uniform values
2. State Pollution: Not cleaning up shader state
3. Compilation Errors: Poor error handling and fallback mechanisms
4. Memory Leaks: Not properly cleaning up shader resources
5. Platform Differences: Ignoring GPU capability variations

Next Steps

• Memory Management - Advanced buffer management
• Custom Entity Renderer Example - Complete shader integration example
• Shader Integration Example - Practical shader development

Common Issues

1. Compilation Failures: Always check shader logs for errors
2. Performance Drops: Profile individual shader passes
3. Visual Artifacts: Verify uniform values and texture sampling
4. State Conflicts: Properly manage OpenGL state changes
5. Platform Compatibility: Test on different hardware configurations