RHI: Add Compute Pipeline abstraction with D3D12 and OpenGL support

- Add SetComputeShader/GetComputeShader/HasComputeShader to RHIPipelineState
- Add m_computePipelineState for D3D12 compute PSO
- Add m_computeProgram/m_computeShader for OpenGL
- Fix OpenGLCommandList::DispatchCompute bug (was ignoring x,y,z params)
- Fix OpenGLShader::GetID usage in OpenGLPipelineState
- Mark Priority 8 as completed in RHI_Design_Issues.md

engine/src/RHI/D3D12/D3D12PipelineState.cpp

@@ -1,4 +1,5 @@
 #include "XCEngine/RHI/D3D12/D3D12PipelineState.h"
+#include "XCEngine/RHI/D3D12/D3D12Shader.h"
 #include <cstring>
 
 namespace XCEngine {
@@ -121,8 +122,19 @@ void D3D12PipelineState::SetShaderBytecodes(const D3D12_SHADER_BYTECODE& vs, con
     m_gsBytecode = gs;
 }
 
+void D3D12PipelineState::SetComputeShader(RHIShader* shader) {
+    m_computeShader = shader;
+}
+
+void D3D12PipelineState::SetComputeShaderBytecodes(const D3D12_SHADER_BYTECODE& cs) {
+    m_csBytecode = cs;
+}
+
 bool D3D12PipelineState::Finalize() {
     if (m_finalized) return true;
+    if (HasComputeShader()) {
+        return CreateD3D12ComputePSO();
+    }
     return CreateD3D12PSO();
 }
 
@@ -190,8 +202,27 @@ bool D3D12PipelineState::CreateD3D12PSO() {
     return true;
 }
 
+bool D3D12PipelineState::CreateD3D12ComputePSO() {
+    if (!m_csBytecode.pShaderBytecode || !m_csBytecode.BytecodeLength) {
+        return false;
+    }
+
+    D3D12_COMPUTE_PIPELINE_STATE_DESC desc = {};
+    desc.pRootSignature = m_rootSignature;
+    desc.CS = m_csBytecode;
+
+    HRESULT hr = m_device->CreateComputePipelineState(&desc, IID_PPV_ARGS(&m_computePipelineState));
+    if (FAILED(hr)) {
+        return false;
+    }
+
+    m_finalized = true;
+    return true;
+}
+
 void D3D12PipelineState::Shutdown() {
     m_pipelineState.Reset();
+    m_computePipelineState.Reset();
     m_finalized = false;
 }
 

engine/src/RHI/OpenGL/OpenGLCommandList.cpp

@@ -271,11 +271,8 @@ void OpenGLCommandList::DispatchIndirect(unsigned int buffer, size_t offset) {
     glBindBuffer(GL_DISPATCH_INDIRECT_BUFFER, 0);
 }
 
-void OpenGLCommandList::DispatchCompute(unsigned int x, unsigned int y, unsigned int z, unsigned int groupX, unsigned int groupY, unsigned int groupZ) {
-    glDispatchCompute(groupX, groupY, groupZ);
-    (void)x;
-    (void)y;
-    (void)z;
+void OpenGLCommandList::DispatchCompute(unsigned int x, unsigned int y, unsigned int z) {
+    glDispatchCompute(x, y, z);
 }
 
 void OpenGLCommandList::MemoryBarrier(unsigned int barriers) {

engine/src/RHI/OpenGL/OpenGLPipelineState.cpp

@@ -1,4 +1,5 @@
 #include "XCEngine/RHI/OpenGL/OpenGLPipelineState.h"
+#include "XCEngine/RHI/OpenGL/OpenGLShader.h"
 #include <glad/glad.h>
 
 namespace XCEngine {
@@ -37,6 +38,16 @@ void OpenGLPipelineState::SetRenderTargetFormats(uint32_t count, const uint32_t*
 void OpenGLPipelineState::SetSampleCount(uint32_t count) {
 }
 
+void OpenGLPipelineState::SetComputeShader(RHIShader* shader) {
+    m_computeShader = shader;
+    if (shader) {
+        OpenGLShader* glShader = static_cast<OpenGLShader*>(shader);
+        m_computeProgram = glShader->GetID();
+    } else {
+        m_computeProgram = 0;
+    }
+}
+
 PipelineStateHash OpenGLPipelineState::GetHash() const {
     PipelineStateHash hash = {};
     return hash;
@@ -44,11 +55,15 @@ PipelineStateHash OpenGLPipelineState::GetHash() const {
 
 void OpenGLPipelineState::Shutdown() {
     m_program = 0;
+    m_computeProgram = 0;
+    m_computeShader = nullptr;
     m_programAttached = false;
 }
 
 void OpenGLPipelineState::Bind() {
-    if (m_programAttached) {
+    if (HasComputeShader()) {
+        glUseProgram(m_computeProgram);
+    } else if (m_programAttached) {
         glUseProgram(m_program);
     }
     Apply();