EXAMPLE 5: Tessellation Shaders

samples/sample/main.cpp

@@ -179,6 +179,8 @@ VkPipelineLayout CreatePipelineLayout(std::vector<VkDescriptorSetLayout> descrip
 
 VkPipeline CreateGraphicsPipeline(VkPipelineLayout pipelineLayout, VkRenderPass renderPass, unsigned int subpass) {
     VkShaderModule vertShaderModule = createShaderModule("sample/shaders/shader.vert.spv", device->GetVulkanDevice());
+	VkShaderModule tescShaderModule = createShaderModule("sample/shaders/shader.tesc.spv", device->GetVulkanDevice());
+	VkShaderModule teseShaderModule = createShaderModule("sample/shaders/shader.tese.spv", device->GetVulkanDevice());
     VkShaderModule fragShaderModule = createShaderModule("sample/shaders/shader.frag.spv", device->GetVulkanDevice());
 
     // Assign each shader module to the appropriate stage in the pipeline
@@ -188,13 +190,25 @@ VkPipeline CreateGraphicsPipeline(VkPipelineLayout pipelineLayout, VkRenderPass
     vertShaderStageInfo.module = vertShaderModule;
     vertShaderStageInfo.pName = "main";
 
+	VkPipelineShaderStageCreateInfo tescShaderStageInfo = {};
+	tescShaderStageInfo.sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO;
+	tescShaderStageInfo.stage = VK_SHADER_STAGE_TESSELLATION_CONTROL_BIT;
+	tescShaderStageInfo.module = tescShaderModule;
+	tescShaderStageInfo.pName = "main";
+
+	VkPipelineShaderStageCreateInfo teseShaderStageInfo = {};
+	teseShaderStageInfo.sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO;
+	teseShaderStageInfo.stage = VK_SHADER_STAGE_TESSELLATION_EVALUATION_BIT;
+	teseShaderStageInfo.module = teseShaderModule;
+	teseShaderStageInfo.pName = "main";
+
     VkPipelineShaderStageCreateInfo fragShaderStageInfo = {};
     fragShaderStageInfo.sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO;
     fragShaderStageInfo.stage = VK_SHADER_STAGE_FRAGMENT_BIT;
     fragShaderStageInfo.module = fragShaderModule;
     fragShaderStageInfo.pName = "main";
 
-    VkPipelineShaderStageCreateInfo shaderStages[] = { vertShaderStageInfo, fragShaderStageInfo };
+    VkPipelineShaderStageCreateInfo shaderStages[] = { vertShaderStageInfo, tescShaderStageInfo, teseShaderStageInfo, fragShaderStageInfo };
 
     // --- Set up fixed-function stages ---
 
@@ -230,9 +244,16 @@ VkPipeline CreateGraphicsPipeline(VkPipelineLayout pipelineLayout, VkRenderPass
     // Input assembly
     VkPipelineInputAssemblyStateCreateInfo inputAssembly = {};
     inputAssembly.sType = VK_STRUCTURE_TYPE_PIPELINE_INPUT_ASSEMBLY_STATE_CREATE_INFO;
-    inputAssembly.topology = VK_PRIMITIVE_TOPOLOGY_TRIANGLE_LIST;
+    inputAssembly.topology = VK_PRIMITIVE_TOPOLOGY_PATCH_LIST;
     inputAssembly.primitiveRestartEnable = VK_FALSE;
 
+	// Tessellation state
+	VkPipelineTessellationStateCreateInfo tessellationInfo = {};
+	tessellationInfo.sType = VK_STRUCTURE_TYPE_PIPELINE_TESSELLATION_STATE_CREATE_INFO;
+	tessellationInfo.pNext = NULL;
+	tessellationInfo.flags = 0;
+	tessellationInfo.patchControlPoints = 1;
+
     // Viewports and Scissors (rectangles that define in which regions pixels are stored)
     VkViewport viewport = {};
     viewport.x = 0.0f;
@@ -258,7 +279,7 @@ VkPipeline CreateGraphicsPipeline(VkPipelineLayout pipelineLayout, VkRenderPass
     rasterizer.sType = VK_STRUCTURE_TYPE_PIPELINE_RASTERIZATION_STATE_CREATE_INFO;
     rasterizer.depthClampEnable = VK_FALSE;
     rasterizer.rasterizerDiscardEnable = VK_FALSE;
-    rasterizer.polygonMode = VK_POLYGON_MODE_FILL;
+	rasterizer.polygonMode = VK_POLYGON_MODE_LINE;
     rasterizer.lineWidth = 1.0f;
     rasterizer.cullMode = VK_CULL_MODE_BACK_BIT;
     rasterizer.frontFace = VK_FRONT_FACE_CLOCKWISE;
@@ -304,10 +325,11 @@ VkPipeline CreateGraphicsPipeline(VkPipelineLayout pipelineLayout, VkRenderPass
     // --- Create graphics pipeline ---
     VkGraphicsPipelineCreateInfo pipelineInfo = {};
     pipelineInfo.sType = VK_STRUCTURE_TYPE_GRAPHICS_PIPELINE_CREATE_INFO;
-    pipelineInfo.stageCount = 2;
+    pipelineInfo.stageCount = 4;
     pipelineInfo.pStages = shaderStages;
     pipelineInfo.pVertexInputState = &vertexInputInfo;
     pipelineInfo.pInputAssemblyState = &inputAssembly;
+	pipelineInfo.pTessellationState = &tessellationInfo;
     pipelineInfo.pViewportState = &viewportState;
     pipelineInfo.pRasterizationState = &rasterizer;
     pipelineInfo.pMultisampleState = &multisampling;
@@ -327,6 +349,8 @@ VkPipeline CreateGraphicsPipeline(VkPipelineLayout pipelineLayout, VkRenderPass
 
     // No need for the shader modules anymore
     vkDestroyShaderModule(device->GetVulkanDevice(), vertShaderModule, nullptr);
+	vkDestroyShaderModule(device->GetVulkanDevice(), tescShaderModule, nullptr);
+	vkDestroyShaderModule(device->GetVulkanDevice(), teseShaderModule, nullptr);
     vkDestroyShaderModule(device->GetVulkanDevice(), fragShaderModule, nullptr);
 
     return pipeline;
@@ -378,7 +402,7 @@ std::vector<VkFramebuffer> CreateFrameBuffers(VkRenderPass renderPass) {
 }
 
 int main(int argc, char** argv) {
-    static constexpr char* applicationName = "Hello Compute";
+    static constexpr char* applicationName = "Hello Tessellation";
     InitializeWindow(640, 480, applicationName);
 
     unsigned int glfwExtensionCount = 0;
@@ -393,7 +417,12 @@ int main(int argc, char** argv) {
 
     instance->PickPhysicalDevice({ VK_KHR_SWAPCHAIN_EXTENSION_NAME }, QueueFlagBit::GraphicsBit | QueueFlagBit::TransferBit | QueueFlagBit::ComputeBit | QueueFlagBit::PresentBit, surface);
 
-    device = instance->CreateDevice(QueueFlagBit::GraphicsBit | QueueFlagBit::TransferBit | QueueFlagBit::ComputeBit | QueueFlagBit::PresentBit);
+	// --- Specify the set of device features used ---
+	VkPhysicalDeviceFeatures deviceFeatures = {};
+	deviceFeatures.tessellationShader = VK_TRUE;
+	deviceFeatures.fillModeNonSolid = VK_TRUE;
+
+    device = instance->CreateDevice(QueueFlagBit::GraphicsBit | QueueFlagBit::TransferBit | QueueFlagBit::ComputeBit | QueueFlagBit::PresentBit, deviceFeatures);
     swapchain = device->CreateSwapChain(surface);
 
     VkCommandPoolCreateInfo poolInfo = {};
@@ -411,36 +440,29 @@ int main(int argc, char** argv) {
     cameraTransforms.projectionMatrix = glm::perspective(static_cast<float>(45 * M_PI / 180), 640.f / 480.f, 0.1f, 1000.f);
 
     ModelUBO modelTransforms;
-    modelTransforms.modelMatrix = glm::rotate(glm::mat4(1.f), static_cast<float>(15 * M_PI / 180), glm::vec3(0.f, 0.f, 1.f));
+	modelTransforms.modelMatrix = glm::mat4(1.0);//glm::rotate(glm::mat4(1.f), static_cast<float>(15 * M_PI / 180), glm::vec3(0.f, 0.f, 1.f));
 
     std::vector<Vertex> vertices = {
-        { { 0.5f,  0.5f, 0.0f, 1.f },{ 0.0f, 1.0f, 0.0f, 1.f } },
-        { { -0.5f, 0.5f, 0.0f, 1.f },{ 0.0f, 0.0f, 1.0f, 1.f } },
-        { { 0.0f, -0.5f, 0.0f, 1.f },{ 1.0f, 0.0f, 0.0f, 1.f } }
+        { { 0.0f,  1.0f, 0.0f, 1.f },{ 0.0f, 1.0f, 0.0f, 1.f } },
     };
 
-    std::vector<unsigned int> indices = { 0, 1, 2 };
-
     unsigned int vertexBufferSize = static_cast<uint32_t>(vertices.size() * sizeof(vertices[0]));
-    unsigned int indexBufferSize = static_cast<uint32_t>(indices.size() * sizeof(indices[0]));
 
     // Create vertex and index buffers
     VkBuffer vertexBuffer = CreateBuffer(device, VK_BUFFER_USAGE_VERTEX_BUFFER_BIT | VK_BUFFER_USAGE_STORAGE_BUFFER_BIT, vertexBufferSize);
-    VkBuffer indexBuffer = CreateBuffer(device, VK_BUFFER_USAGE_INDEX_BUFFER_BIT, indexBufferSize);
-    unsigned int vertexBufferOffsets[2];
-    VkDeviceMemory vertexBufferMemory = AllocateMemoryForBuffers(device, { vertexBuffer, indexBuffer }, VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT, vertexBufferOffsets);
+    unsigned int vertexBufferOffsets[1];
+    VkDeviceMemory vertexBufferMemory = AllocateMemoryForBuffers(device, { vertexBuffer }, VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT, vertexBufferOffsets);
 
     // Copy data to buffer memory
     {
         char* data;
-        vkMapMemory(device->GetVulkanDevice(), vertexBufferMemory, 0, vertexBufferOffsets[1] + indexBufferSize, 0, reinterpret_cast<void**>(&data));
+        vkMapMemory(device->GetVulkanDevice(), vertexBufferMemory, 0, vertexBufferSize, 0, reinterpret_cast<void**>(&data));
         memcpy(data + vertexBufferOffsets[0], vertices.data(), vertexBufferSize);
-        memcpy(data + vertexBufferOffsets[1], indices.data(), indexBufferSize);
         vkUnmapMemory(device->GetVulkanDevice(), vertexBufferMemory);
     }
 
     // Bind the memory to the buffers
-    BindMemoryForBuffers(device, vertexBufferMemory, { vertexBuffer, indexBuffer }, vertexBufferOffsets);
+    BindMemoryForBuffers(device, vertexBufferMemory, { vertexBuffer }, vertexBufferOffsets);
 
     // Create uniform buffers
     VkBuffer cameraBuffer = CreateBuffer(device, VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT, sizeof(CameraUBO));
@@ -467,7 +489,7 @@ int main(int argc, char** argv) {
     });
 
     VkDescriptorSetLayout cameraSetLayout = CreateDescriptorSetLayout({
-        { 0, VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER, 1, VK_SHADER_STAGE_VERTEX_BIT, nullptr },
+        { 0, VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER, 1, VK_SHADER_STAGE_TESSELLATION_EVALUATION_BIT , nullptr },
     });
 
     VkDescriptorSetLayout modelSetLayout = CreateDescriptorSetLayout({
@@ -609,11 +631,8 @@ int main(int argc, char** argv) {
         VkDeviceSize offsets[1] = { 0 };
         vkCmdBindVertexBuffers(commandBuffers[i], 0, 1, &vertexBuffer, offsets);
 
-        // Bind triangle index buffer
-        vkCmdBindIndexBuffer(commandBuffers[i], indexBuffer, 0, VK_INDEX_TYPE_UINT32);
-
-        // Draw indexed triangle
-        vkCmdDrawIndexed(commandBuffers[i], 3, 1, 0, 0, 1);
+        // Draw single point which will tessellate to a triangle
+		vkCmdDraw(commandBuffers[i], 1, 1, 0, 1);
 
         vkCmdEndRenderPass(commandBuffers[i]);
 
@@ -665,7 +684,6 @@ int main(int argc, char** argv) {
     delete camera;
 
     vkDestroyBuffer(device->GetVulkanDevice(), vertexBuffer, nullptr);
-    vkDestroyBuffer(device->GetVulkanDevice(), indexBuffer, nullptr);
     vkFreeMemory(device->GetVulkanDevice(), vertexBufferMemory, nullptr);
 
     vkDestroyBuffer(device->GetVulkanDevice(), cameraBuffer, nullptr);

samples/sample/shaders/shader.frag

@@ -1,10 +1,8 @@
 #version 450
 #extension GL_ARB_separate_shader_objects : enable
 
-layout(location = 0) in vec3 fragColor;
-
 layout(location = 0) out vec4 outColor;
 
 void main() {
-    outColor = vec4(fragColor, 1.0);
+    outColor = vec4(1.0);
 }

samples/sample/shaders/shader.tesc

@@ -0,0 +1,15 @@
+#version 440
+#extension GL_ARB_separate_shader_objects : enable
+
+layout(vertices = 1) out;
+
+void main() {
+	gl_out[gl_InvocationID].gl_Position = gl_in[gl_InvocationID].gl_Position;
+
+	gl_TessLevelInner[0] = 2.0;
+	gl_TessLevelInner[1] = 2.0;
+	gl_TessLevelOuter[0] = 2.0;
+	gl_TessLevelOuter[1] = 2.0;
+	gl_TessLevelOuter[2] = 2.0;
+	gl_TessLevelOuter[3] = 2.0;
+}

samples/sample/shaders/shader.tese

@@ -0,0 +1,16 @@
+#version 440
+#extension GL_ARB_separate_shader_objects : enable
+
+layout(quads, equal_spacing, ccw) in;
+
+layout(set = 0, binding = 0) uniform CameraUBO {
+	mat4 viewMatrix;
+	mat4 projectionMatrix;
+};
+
+void main() {
+	float u = gl_TessCoord.x;
+	float v = gl_TessCoord.y;
+
+	gl_Position = projectionMatrix * viewMatrix * (gl_in[0].gl_Position + vec4(1.0 - u, v, 0.0, 0.0));
+}

samples/sample/shaders/shader.vert

@@ -1,25 +1,16 @@
 #version 450
 #extension GL_ARB_separate_shader_objects : enable
 
-layout(set = 0, binding = 0) uniform CameraUBO {
-	mat4 viewMatrix;
-	mat4 projectionMatrix;
-};
-
 layout(set = 1, binding = 0) uniform ModelUBO {
 	mat4 modelMatrix;
 };
 
 layout (location = 0) in vec3 position;
-layout (location = 1) in vec3 color;
 
 out gl_PerVertex {
     vec4 gl_Position;
 };
 
-layout(location = 0) out vec3 fragColor;
-
 void main() {
-    gl_Position = projectionMatrix * viewMatrix * modelMatrix * vec4(position, 1.0);
-    fragColor = color;
+    gl_Position = modelMatrix * vec4(position, 1.0);
 }

samples/sample/vulkan_instance.cpp

@@ -283,7 +283,7 @@ void VulkanInstance::PickPhysicalDevice(std::vector<const char*> deviceExtension
     vkGetPhysicalDeviceMemoryProperties(physicalDevice, &deviceMemoryProperties);
 }
 
-VulkanDevice* VulkanInstance::CreateDevice(QueueFlagBits requiredQueues) {
+VulkanDevice* VulkanInstance::CreateDevice(QueueFlagBits requiredQueues, VkPhysicalDeviceFeatures deviceFeatures) {
     std::set<int> uniqueQueueFamilies;
     bool queueSupport = true;
     for (unsigned int i = 0; i < requiredQueues.size(); ++i) {
@@ -308,9 +308,6 @@ VulkanDevice* VulkanInstance::CreateDevice(QueueFlagBits requiredQueues) {
         queueCreateInfos.push_back(queueCreateInfo);
     }
 
-    // --- Specify the set of device features used ---
-    VkPhysicalDeviceFeatures deviceFeatures = {};
-
     // --- Create logical device ---
     VkDeviceCreateInfo createInfo = {};
     createInfo.sType = VK_STRUCTURE_TYPE_DEVICE_CREATE_INFO;

samples/sample/vulkan_instance.h

@@ -25,7 +25,7 @@ class VulkanInstance {
 
     void PickPhysicalDevice(std::vector<const char*> deviceExtensions, QueueFlagBits requiredQueues, VkSurfaceKHR surface = VK_NULL_HANDLE);
 
-    VulkanDevice* CreateDevice(QueueFlagBits requiredQueues);
+    VulkanDevice* CreateDevice(QueueFlagBits requiredQueues, VkPhysicalDeviceFeatures deviceFeatures);
 
     ~VulkanInstance();