WIP: fix: correct SSBO/UBO binding point resolution in material system

jme3-core/src/main/java/com/jme3/material/Material.java

@@ -881,14 +881,10 @@ private void updateShaderMaterialParameter(Renderer renderer, VarType type, Shad
             ShaderBufferBlock.BufferType btype;
             if (type == VarType.ShaderStorageBufferObject) {
                 btype = ShaderBufferBlock.BufferType.ShaderStorageBufferObject;
-                bufferBlock.setBufferObject(btype, bufferObject);
-                renderer.setShaderStorageBufferObject(unit.bufferUnit, bufferObject); // TODO: probably not needed
             } else {
                 btype = ShaderBufferBlock.BufferType.UniformBufferObject;
-                bufferBlock.setBufferObject(btype, bufferObject);
-                renderer.setUniformBufferObject(unit.bufferUnit, bufferObject); // TODO: probably not needed
             }
-            unit.bufferUnit++;
+            bufferBlock.setBufferObject(btype, bufferObject);
         } else {
             Uniform uniform = shader.getUniform(param.getPrefixedName());
             if (!override && uniform.isSetByCurrentMaterial())

jme3-core/src/main/java/com/jme3/renderer/opengl/GL3.java

@@ -227,4 +227,20 @@ public interface GL3 extends GL2 {
      *                            uniformBlockIndex within program.
      */
     public void glUniformBlockBinding(int program, int uniformBlockIndex, int uniformBlockBinding);
+
+    /**
+     * <p><a target="_blank" href="http://docs.gl/gl4/glGetActiveUniformBlock">Reference Page</a></p>
+     *
+     * Queries information about an active uniform block.
+     *
+     * @param program           the name of a program containing the uniform block.
+     * @param uniformBlockIndex the index of the uniform block within program.
+     * @param pname             the name of the parameter to query. One of:
+     *  {@link #GL_UNIFORM_BLOCK_BINDING}
+     *  {@link #GL_UNIFORM_BLOCK_DATA_SIZE}
+     *  {@link #GL_UNIFORM_BLOCK_NAME_LENGTH}
+     *  {@link #GL_UNIFORM_BLOCK_ACTIVE_UNIFORMS}
+     * @return the value of the queried parameter.
+     */
+    public int glGetActiveUniformBlocki(int program, int uniformBlockIndex, int pname);
 }

jme3-core/src/main/java/com/jme3/renderer/opengl/GL4.java

@@ -31,6 +31,8 @@
  */
 package com.jme3.renderer.opengl;
 
+import java.nio.IntBuffer;
+
 /**
  * GL functions only available on vanilla desktop OpenGL 4.0.
  * 
@@ -77,6 +79,11 @@ public interface GL4 extends GL3 {
     public static final int GL_SHADER_STORAGE_BUFFER = 0x90D2;
     public static final int GL_SHADER_STORAGE_BLOCK = 0x92E6;
 
+    /**
+     * Accepted by the {@code props} parameter of GetProgramResourceiv.
+     */
+    public static final int GL_BUFFER_BINDING = 0x9302;
+
     /**
      *  Accepted by the <pname> parameter of GetIntegerv, GetBooleanv,
      *  GetInteger64v, GetFloatv, and GetDoublev:
@@ -124,7 +131,22 @@ public interface GL4 extends GL3 {
      * @param storageBlockBinding The index storage block binding to associate with the specified storage block.
      */
     public void glShaderStorageBlockBinding(int program, int storageBlockIndex, int storageBlockBinding);
-
+
+    /**
+     * <p><a target="_blank" href="http://docs.gl/gl4/glGetProgramResource">Reference Page</a></p>
+     *
+     * Retrieves values for multiple properties of a single active resource within a program object.
+     *
+     * @param program          the name of a program object whose resources to query.
+     * @param programInterface a token identifying the interface within program containing the resource named name.
+     * @param index            the active resource index.
+     * @param props            an array of properties to query.
+     * @param length           an array that will receive the number of values written to params.
+     * @param params           an array that will receive the property values.
+     */
+    public void glGetProgramResourceiv(int program, int programInterface, int index, IntBuffer props, IntBuffer length, IntBuffer params);
+
+
     /**
      * Binds a single level of a texture to an image unit for the purpose of reading
      * and writing it from shaders.

jme3-core/src/main/java/com/jme3/renderer/opengl/GLRenderer.java

@@ -1456,7 +1456,6 @@ protected void updateShaderBufferBlock(final Shader shader, final ShaderBufferBl
 
         final BufferObject bufferObject = bufferBlock.getBufferObject();
         final BufferType bufferType = bufferBlock.getType();
-
 
         if (bufferObject.isUpdateNeeded()) {
             if (bufferType == BufferType.ShaderStorageBufferObject) {
@@ -1473,35 +1472,52 @@ protected void updateShaderBufferBlock(final Shader shader, final ShaderBufferBl
 
         final int shaderId = shader.getId();
 
-        int bindingPoint = bufferObject.getBinding();
+        // Resolve the block index (location) from the compiled shader
+        int blockIndex = bufferBlock.getLocation();
+        if (blockIndex < 0) {
+            if (bufferType == BufferType.ShaderStorageBufferObject) {
+                blockIndex = gl4.glGetProgramResourceIndex(shaderId, GL4.GL_SHADER_STORAGE_BLOCK, bufferBlock.getName());
+            } else {
+                blockIndex = gl3.glGetUniformBlockIndex(shaderId, bufferBlock.getName());
+            }
+            bufferBlock.setLocation(blockIndex);
+        }
+
+        // Block not found in the shader — skip silently
+        if (blockIndex < 0 || blockIndex == NativeObject.INVALID_ID) {
+            bufferBlock.clearUpdateNeeded();
+            return;
+        }
+
+        // Resolve the binding point for this block. First try to read the
+        // binding declared in the shader (layout(binding=N)). If the query
+        // returns 0 the shader may not have an explicit binding, so fall
+        // back to blockIndex to avoid multiple blocks colliding on point 0.
+        int bindingPoint = bufferBlock.getBinding();
+        if (bindingPoint < 0) {
+            if (bufferType == BufferType.ShaderStorageBufferObject) {
+                bindingPoint = queryShaderStorageBlockBinding(shaderId, blockIndex);
+            } else {
+                bindingPoint = gl3.glGetActiveUniformBlocki(shaderId, blockIndex, GL3.GL_UNIFORM_BLOCK_BINDING);
+            }
+            if (bindingPoint == 0) {
+                bindingPoint = blockIndex;
+            }
+            if (bufferType == BufferType.ShaderStorageBufferObject) {
+                gl4.glShaderStorageBlockBinding(shaderId, blockIndex, bindingPoint);
+            } else {
+                gl3.glUniformBlockBinding(shaderId, blockIndex, bindingPoint);
+            }
+            bufferBlock.setBinding(bindingPoint);
+        }
 
         switch (bufferType) {
             case UniformBufferObject: {
-                setUniformBufferObject(bindingPoint, bufferObject); // rebind buffer if needed
-                if (bufferBlock.isUpdateNeeded()) {
-                    int blockIndex = bufferBlock.getLocation();
-                    if (blockIndex < 0) {
-                        blockIndex = gl3.glGetUniformBlockIndex(shaderId, bufferBlock.getName());
-                        bufferBlock.setLocation(blockIndex);
-                    }
-                    if (bufferBlock.getLocation() != NativeObject.INVALID_ID) {
-                        gl3.glUniformBlockBinding(shaderId, bufferBlock.getLocation(), bindingPoint);
-                    } 
-                }
+                setUniformBufferObject(bindingPoint, bufferObject);
                 break;
             }
             case ShaderStorageBufferObject: {
-                setShaderStorageBufferObject(bindingPoint, bufferObject); // rebind buffer if needed
-                if (bufferBlock.isUpdateNeeded() ) {
-                    int blockIndex = bufferBlock.getLocation();
-                    if (blockIndex < 0) {
-                        blockIndex = gl4.glGetProgramResourceIndex(shaderId, GL4.GL_SHADER_STORAGE_BLOCK, bufferBlock.getName());
-                        bufferBlock.setLocation(blockIndex);
-                    }
-                    if (bufferBlock.getLocation() != NativeObject.INVALID_ID) {
-                        gl4.glShaderStorageBlockBinding(shaderId, bufferBlock.getLocation(), bindingPoint);
-                    }
-                }
+                setShaderStorageBufferObject(bindingPoint, bufferObject);
                 break;
             }
             default: {
@@ -1512,6 +1528,22 @@ protected void updateShaderBufferBlock(final Shader shader, final ShaderBufferBl
         bufferBlock.clearUpdateNeeded();
     }
 
+    /**
+     * Queries the binding point of a shader storage block using
+     * glGetProgramResourceiv with GL_BUFFER_BINDING.
+     *
+     * @param program the shader program id.
+     * @param blockIndex the block index within the program.
+     * @return the binding point assigned to the block.
+     */
+    private int queryShaderStorageBlockBinding(int program, int blockIndex) {
+        IntBuffer props = BufferUtils.createIntBuffer(1);
+        props.put(GL4.GL_BUFFER_BINDING).flip();
+        IntBuffer params = BufferUtils.createIntBuffer(1);
+        gl4.glGetProgramResourceiv(program, GL4.GL_SHADER_STORAGE_BLOCK, blockIndex, props, null, params);
+        return params.get(0);
+    }
+
     protected void updateShaderUniforms(Shader shader) {
         ListMap<String, Uniform> uniforms = shader.getUniformMap();
         for (int i = 0; i < uniforms.size(); i++) {

jme3-core/src/main/java/com/jme3/shader/ShaderBufferBlock.java

@@ -53,6 +53,11 @@ public static enum BufferType {
     protected WeakReference<BufferObject> bufferObjectRef;
     protected BufferType type;
 
+    /**
+     * The binding point assigned to this block, or -1 if not yet assigned.
+     */
+    protected int binding = -1;
+
     /**
      * Set the new buffer object.
      *
@@ -90,11 +95,30 @@ public void clearUpdateNeeded(){
         updateNeeded = false;
     }
 
+    /**
+     * Get the binding point assigned to this block.
+     *
+     * @return the binding point, or -1 if not yet assigned.
+     */
+    public int getBinding() {
+        return binding;
+    }
+
+    /**
+     * Set the binding point for this block.
+     *
+     * @param binding the binding point.
+     */
+    public void setBinding(int binding) {
+        this.binding = binding;
+    }
+
     /**
      * Reset this storage block.
      */
     public void reset() {
         location = -1;
+        binding = -1;
         updateNeeded = true;
     }
 

jme3-core/src/main/java/com/jme3/shader/bufferobject/BufferObject.java

@@ -158,6 +158,7 @@ public void initializeEmpty(int length) {
             BufferUtils.destroyDirectBuffer(data);
         }
         this.data = BufferUtils.createByteBuffer(length);
+        setUpdateNeeded();
     }
 
 

jme3-lwjgl/src/main/java/com/jme3/renderer/lwjgl/LwjglGL.java

@@ -660,4 +660,14 @@ public void glBindBufferBase(final int target, final int index, final int buffer
     public void glUniformBlockBinding(final int program, final int uniformBlockIndex, final int uniformBlockBinding) {
         GL31.glUniformBlockBinding(program, uniformBlockIndex, uniformBlockBinding);
     }
+
+    @Override
+    public int glGetActiveUniformBlocki(final int program, final int uniformBlockIndex, final int pname) {
+        return GL31.glGetActiveUniformBlocki(program, uniformBlockIndex, pname);
+    }
+
+    @Override
+    public void glGetProgramResourceiv(final int program, final int programInterface, final int index, IntBuffer props, IntBuffer length, IntBuffer params) {
+        GL43.glGetProgramResource(program, programInterface, index, props, length, params);
+    }
 }

jme3-lwjgl3/src/main/java/com/jme3/renderer/lwjgl/LwjglGL.java

@@ -698,5 +698,15 @@ public void glBindBufferBase(final int target, final int index, final int buffer
     public void glUniformBlockBinding(final int program, final int uniformBlockIndex, final int uniformBlockBinding) {
         GL31.glUniformBlockBinding(program, uniformBlockIndex, uniformBlockBinding);
     }
-
+
+    @Override
+    public int glGetActiveUniformBlocki(final int program, final int uniformBlockIndex, final int pname) {
+        return GL31.glGetActiveUniformBlocki(program, uniformBlockIndex, pname);
+    }
+
+    @Override
+    public void glGetProgramResourceiv(final int program, final int programInterface, final int index, IntBuffer props, IntBuffer length, IntBuffer params) {
+        GL43.glGetProgramResourceiv(program, programInterface, index, props, length, params);
+    }
+
 }