Added support for tessellation shaders. Resolves #73

README.md

@@ -22,7 +22,7 @@ Fwog is interested in providing an abstraction of a *subset* of OpenGL. That mea
 
 - The default uniform block (e.g., uniforms set with glUniform*)
   - Alternative: uniform and storage buffers
-- Geometry and tessellation control/evaluation shaders
+- Geometry shaders
   - Alternative: compute shaders
 - Multisampled rasterization
 - Multiple viewports/layered rendering

docs/index.rst

@@ -23,7 +23,7 @@ Caveats
 Given Fwog's goals, there are a number of features that the API does not expose:
 
 - The default uniform block (i.e., uniforms set with ``glUniform*``)
-- Geometry and tessellation shaders
+- Geometry shaders
 - Multi-viewport/layered rendering
 - Multisampled rasterization
 - Transform feedback

include/Fwog/BasicTypes.h

@@ -327,7 +327,9 @@ namespace Fwog
     TRIANGLE_LIST,
     TRIANGLE_STRIP,
     TRIANGLE_FAN,
-    // TODO: add more toplogies that are deemed useful
+
+    /// @note Available only in pipelines with tessellation shaders
+    PATCH_LIST,
   };
 
   enum class PolygonMode : uint32_t

include/Fwog/Pipeline.h

@@ -29,6 +29,11 @@ namespace Fwog
     std::span<const VertexInputBindingDescription> vertexBindingDescriptions = {};
   };
 
+  struct TessellationState
+  {
+    uint32_t patchControlPoints; // glPatchParameteri(GL_PATCH_VERTICES, ...)
+  };
+
   // TODO: see what rasterization state can be dynamic instead
   struct RasterizationState
   {
@@ -108,8 +113,15 @@ namespace Fwog
     /// @brief Optional pointer to a fragment shader
     const Shader* fragmentShader          = nullptr;
 
+    /// @brief Optional pointer to a tessellation control shader
+    const Shader* tessellationControlShader = nullptr;
+
+    /// @brief Optional pointer to a tessellation evaluation shader
+    const Shader* tessellationEvaluationShader = nullptr;
+
     InputAssemblyState inputAssemblyState = {};
     VertexInputState vertexInputState     = {};
+    TessellationState tessellationState   = {};
     RasterizationState rasterizationState = {};
     DepthState depthState                 = {};
     StencilState stencilState             = {};

include/Fwog/Shader.h

@@ -8,6 +8,8 @@ namespace Fwog
   enum class PipelineStage
   {
     VERTEX_SHADER,
+    TESSELLATION_CONTROL_SHADER,
+    TESSELLATION_EVALUATION_SHADER,
     FRAGMENT_SHADER,
     COMPUTE_SHADER
   };

include/Fwog/detail/PipelineManager.h

@@ -25,6 +25,7 @@ namespace Fwog::detail
     std::string name;
     InputAssemblyState inputAssemblyState;
     VertexInputStateOwning vertexInputState;
+    TessellationState tessellationState;
     RasterizationState rasterizationState;
     DepthState depthState;
     StencilState stencilState;

src/Rendering.cpp

@@ -365,7 +365,7 @@ namespace Fwog
       default: FWOG_UNREACHABLE;
       }
     }
-    
+
     if (ri.stencilAttachment)
     {
       switch (ri.stencilAttachment->loadOp)
@@ -638,8 +638,15 @@ namespace Fwog
         glBindVertexArray(context->currentVao);
       }
 
-      //////////////////////////////////////////////////////////////// rasterization
-      const auto& rs = pipelineState->rasterizationState;
+      //////////////////////////////////////////////////////////////// tessellation
+      if (!context->lastGraphicsPipeline || pipelineState->tessellationState.patchControlPoints !=
+                                              context->lastGraphicsPipeline->tessellationState.patchControlPoints)
+      {
+        glPatchParameteri(GL_PATCH_VERTICES, static_cast<GLint>(pipelineState->tessellationState.patchControlPoints));
+      }
+
+        //////////////////////////////////////////////////////////////// rasterization
+        const auto& rs = pipelineState->rasterizationState;
       if (!context->lastGraphicsPipeline ||
           rs.depthClampEnable != context->lastGraphicsPipeline->rasterizationState.depthClampEnable)
       {

src/Shader.cpp

@@ -16,6 +16,8 @@ namespace Fwog
       switch (stage)
       {
       case PipelineStage::VERTEX_SHADER: return GL_VERTEX_SHADER;
+      case PipelineStage::TESSELLATION_CONTROL_SHADER: return GL_TESS_CONTROL_SHADER;
+      case PipelineStage::TESSELLATION_EVALUATION_SHADER: return GL_TESS_EVALUATION_SHADER;
       case PipelineStage::FRAGMENT_SHADER: return GL_FRAGMENT_SHADER;
       case PipelineStage::COMPUTE_SHADER: return GL_COMPUTE_SHADER;
       default: FWOG_UNREACHABLE; return 0;

src/detail/PipelineManager.cpp

@@ -17,8 +17,14 @@ namespace Fwog::detail
       return GraphicsPipelineInfoOwning{
         .name = std::string(info.name),
         .inputAssemblyState = info.inputAssemblyState,
-        .vertexInputState = {{info.vertexInputState.vertexBindingDescriptions.begin(),
-                              info.vertexInputState.vertexBindingDescriptions.end()}},
+        .vertexInputState =
+          {
+            {
+              info.vertexInputState.vertexBindingDescriptions.begin(),
+              info.vertexInputState.vertexBindingDescriptions.end(),
+            },
+          },
+        .tessellationState = info.tessellationState,
         .rasterizationState = info.rasterizationState,
         .depthState = info.depthState,
         .stencilState = info.stencilState,
@@ -58,13 +64,28 @@ namespace Fwog::detail
   uint64_t CompileGraphicsPipelineInternal(const GraphicsPipelineInfo& info)
   {
     FWOG_ASSERT(info.vertexShader && "A graphics pipeline must at least have a vertex shader");
+    if (info.tessellationControlShader || info.tessellationEvaluationShader)
+    {
+      FWOG_ASSERT(info.tessellationControlShader && info.tessellationEvaluationShader &&
+                  "Either both or neither tessellation shader can be present");
+    }
     GLuint program = glCreateProgram();
     glAttachShader(program, info.vertexShader->Handle());
     if (info.fragmentShader)
     {
       glAttachShader(program, info.fragmentShader->Handle());
     }
 
+    if (info.tessellationControlShader)
+    {
+      glAttachShader(program, info.tessellationControlShader->Handle());
+    }
+
+    if (info.tessellationEvaluationShader)
+    {
+      glAttachShader(program, info.tessellationEvaluationShader->Handle());
+    }
+
     std::string infolog;
     if (!LinkProgram(program, infolog))
     {