renderdoc/util/test/demos/vk/vk_triangle_fan.cpp

/******************************************************************************
 * The MIT License (MIT)
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 * Copyright (c) 2019-2026 Baldur Karlsson
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#include "vk_test.h"

RD_TEST(VK_Triangle_Fan, VulkanGraphicsTest)
{
  static constexpr const char *Description =
      "Draws a triangle fan with primitive restart to test different edge cases.";

  int main()
  {
    // initialise, create window, create context, etc
    if(!Init())
      return 3;

    VkPipelineLayout layout = createPipelineLayout(vkh::PipelineLayoutCreateInfo());

    vkh::GraphicsPipelineCreateInfo pipeCreateInfo;

    pipeCreateInfo.layout = layout;
    pipeCreateInfo.renderPass = mainWindow->rp;

    pipeCreateInfo.inputAssemblyState.topology = VK_PRIMITIVE_TOPOLOGY_TRIANGLE_FAN;
    pipeCreateInfo.inputAssemblyState.primitiveRestartEnable = VK_FALSE;

    pipeCreateInfo.vertexInputState.vertexBindingDescriptions = {vkh::vertexBind(0, DefaultA2V)};
    pipeCreateInfo.vertexInputState.vertexAttributeDescriptions = {
        vkh::vertexAttr(0, 0, DefaultA2V, pos),
        vkh::vertexAttr(1, 0, DefaultA2V, col),
        vkh::vertexAttr(2, 0, DefaultA2V, uv),
    };

    pipeCreateInfo.stages = {
        CompileShaderModule(VKDefaultVertex, ShaderLang::glsl, ShaderStage::vert, "main"),
        CompileShaderModule(VKDefaultPixel, ShaderLang::glsl, ShaderStage::frag, "main"),
    };

    VkPipeline pipe = createGraphicsPipeline(pipeCreateInfo);

    pipeCreateInfo.inputAssemblyState.primitiveRestartEnable = VK_TRUE;

    VkPipeline restartpipe = createGraphicsPipeline(pipeCreateInfo);

    const DefaultA2V verts[] = {
        // centre A
        {Vec3f(0.0f, 0.0f, 0.0f), Vec4f(0.0f, 0.0f, 0.0f, 1.0f), Vec2f(0.0f, 0.0f)},

        // fan A
        {Vec3f(-0.8f, 0.0f, 0.0f), Vec4f(1.0f, 0.0f, 0.0f, 1.0f), Vec2f(0.0f, 1.0f)},
        {Vec3f(-0.5f, 0.3f, 0.0f), Vec4f(1.0f, 1.0f, 0.0f, 1.0f), Vec2f(0.0f, 1.0f)},
        {Vec3f(0.0f, 0.5f, 0.0f), Vec4f(0.0f, 1.0f, 0.0f, 1.0f), Vec2f(0.0f, 1.0f)},
        {Vec3f(0.5f, 0.3f, 0.0f), Vec4f(0.0f, 1.0f, 1.0f, 1.0f), Vec2f(0.0f, 1.0f)},
        {Vec3f(0.8f, 0.0f, 0.0f), Vec4f(0.0f, 0.0f, 1.0f, 1.0f), Vec2f(0.0f, 1.0f)},

        // centre B
        {Vec3f(0.0f, -0.75f, 0.0f), Vec4f(1.0f, 1.0f, 1.0f, 1.0f), Vec2f(0.0f, 0.0f)},

        // fan B
        {Vec3f(-0.8f, 0.0f - 0.75f, 0.0f), Vec4f(1.0f, 0.0f, 0.0f, 1.0f), Vec2f(0.0f, 1.0f)},
        {Vec3f(-0.5f, 0.3f - 0.75f, 0.0f), Vec4f(1.0f, 1.0f, 0.0f, 1.0f), Vec2f(0.0f, 1.0f)},
        {Vec3f(0.0f, 0.5f - 0.75f, 0.0f), Vec4f(0.0f, 1.0f, 0.0f, 1.0f), Vec2f(0.0f, 1.0f)},
        {Vec3f(0.5f, 0.3f - 0.75f, 0.0f), Vec4f(0.0f, 1.0f, 1.0f, 1.0f), Vec2f(0.0f, 1.0f)},
        {Vec3f(0.8f, 0.0f - 0.75f, 0.0f), Vec4f(0.0f, 0.0f, 1.0f, 1.0f), Vec2f(0.0f, 1.0f)},
    };

    AllocatedBuffer vb(this,
                       vkh::BufferCreateInfo(sizeof(verts), VK_BUFFER_USAGE_VERTEX_BUFFER_BIT |
                                                                VK_BUFFER_USAGE_TRANSFER_DST_BIT),
                       VmaAllocationCreateInfo({0, VMA_MEMORY_USAGE_CPU_TO_GPU}));

    vb.upload(verts);

    uint32_t indices[13] = {0, 1, 2, 3, 4, 5, ~0U, 6, 7, 8, 9, 10, 11};
    AllocatedBuffer ib(this,
                       vkh::BufferCreateInfo(sizeof(indices), VK_BUFFER_USAGE_INDEX_BUFFER_BIT |
                                                                  VK_BUFFER_USAGE_TRANSFER_DST_BIT),
                       VmaAllocationCreateInfo({0, VMA_MEMORY_USAGE_CPU_TO_GPU}));

    ib.upload(indices);

    while(Running())
    {
      VkCommandBuffer cmd = GetCommandBuffer();

      vkBeginCommandBuffer(cmd, vkh::CommandBufferBeginInfo());

      VkImage swapimg =
          StartUsingBackbuffer(cmd, VK_ACCESS_TRANSFER_WRITE_BIT, VK_IMAGE_LAYOUT_GENERAL);

      vkCmdClearColorImage(cmd, swapimg, VK_IMAGE_LAYOUT_GENERAL,
                           vkh::ClearColorValue(0.2f, 0.2f, 0.2f, 1.0f), 1,
                           vkh::ImageSubresourceRange());

      vkCmdBeginRenderPass(
          cmd, vkh::RenderPassBeginInfo(mainWindow->rp, mainWindow->GetFB(), mainWindow->scissor),
          VK_SUBPASS_CONTENTS_INLINE);

      VkViewport v = mainWindow->viewport;
      v.width /= 2;

      vkCmdBindPipeline(cmd, VK_PIPELINE_BIND_POINT_GRAPHICS, restartpipe);
      vkCmdSetViewport(cmd, 0, 1, &v);
      vkCmdSetScissor(cmd, 0, 1, &mainWindow->scissor);
      vkh::cmdBindVertexBuffers(cmd, 0, {vb.buffer}, {0});
      vkCmdBindIndexBuffer(cmd, ib.buffer, 0, VK_INDEX_TYPE_UINT32);
      vkCmdDrawIndexed(cmd, 13, 1, 0, 0, 0);

      v.x += v.width;
      vkCmdSetViewport(cmd, 0, 1, &v);

      vkCmdBindPipeline(cmd, VK_PIPELINE_BIND_POINT_GRAPHICS, pipe);

      vkCmdDrawIndexed(cmd, 6, 1, 0, 0, 0);

      vkCmdEndRenderPass(cmd);

      FinishUsingBackbuffer(cmd, VK_ACCESS_TRANSFER_WRITE_BIT, VK_IMAGE_LAYOUT_GENERAL);

      vkEndCommandBuffer(cmd);

      Submit(0, 1, {cmd});

      Present();
    }

    return 0;
  }
};

REGISTER_TEST();