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先叨叨

上篇已经创建的CommandPool和CommandBuffer。接下来就可以向CommandBuffer中记录命令了。

Git信息

• repository: https://gitee.com/J8_series/easy-car-ui
• tag: 12-RecordCommands
• url: https://gitee.com/J8_series/easy-car-ui/tree/12-RecordCommands

关键代码

VulkanEnv::RecordCommandBuffer()

1. vkBeginCommandBuffer的作用是重置CommanderBuffer。也表示开始记录Command。
2. vkCmdBeginRenderPass的作用开始一个渲染过程
3. vkCmdBindPipeline将CommandBuffer和Pipeline关联上，表示Commander作用于该Pipeline
4. vkCmdSetViewport和vkCmdSetScissor用来设置视口和裁剪区域。因为在创建Pipline时，设置了这两个state需要动态设置。
5. vkCmdDraw为描画操作。这里我们要描画三个点。
6. vkCmdEndRenderPass 结束渲染过程
7. vkEndCommandBuffer 结束记录CommandBuffer。

以上以kCmd开始的API就是记录到CommanderBuffer中的Command

void VulkanEnv::RecordCommandBuffer()
{VkCommandBufferBeginInfo beginInfo{};beginInfo.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO;if (vkBeginCommandBuffer(m_commandBuffer, &beginInfo) != VK_SUCCESS) {throw std::runtime_error("failed to begin recording command buffer!");}VkRenderPassBeginInfo renderPassInfo{};renderPassInfo.sType = VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO;renderPassInfo.renderPass = m_testPipeline.GetRenderPass();renderPassInfo.framebuffer = m_testPipeline.GetFramebuffer();renderPassInfo.renderArea.offset = {0, 0};renderPassInfo.renderArea.extent = {m_width, m_height};VkClearValue clearColor = {{{0.0f, 0.0f, 0.0f, 1.0f}}};renderPassInfo.clearValueCount = 1;renderPassInfo.pClearValues = &clearColor;vkCmdBeginRenderPass(m_commandBuffer, &renderPassInfo, VK_SUBPASS_CONTENTS_INLINE);vkCmdBindPipeline(m_commandBuffer, VK_PIPELINE_BIND_POINT_GRAPHICS, m_testPipeline.GetPipeline());VkViewport viewport{};viewport.x = 0.0f;viewport.y = 0.0f;viewport.width = (float) m_width;viewport.height = (float) m_height;viewport.minDepth = 0.0f;viewport.maxDepth = 1.0f;vkCmdSetViewport(m_commandBuffer, 0, 1, &viewport);VkRect2D scissor{};scissor.offset = {0, 0};scissor.extent = {m_width, m_height};vkCmdSetScissor(m_commandBuffer, 0, 1, &scissor);vkCmdDraw(m_commandBuffer, 3, 1, 0, 0);vkCmdEndRenderPass(m_commandBuffer);if (vkEndCommandBuffer(m_commandBuffer) != VK_SUCCESS) {throw std::runtime_error("failed to record command buffer!");}
}

编译并运行代码

能编译成功即可，下一篇将会开始真正的渲染。