如何在Vulkan中绘制图元？

Question

假设Vulkan已被初始化，则要记录到命令缓冲区中，有一个帧缓冲区和一个渲染通道，如何使用Vulkan绘制原始2D几何形状？

vkCmdBeginRenderPass(command_buffer, &render_pass_info, VK_SUBPASS_CONTENTS_INLINE);

// Draw primitives here

vkCmdEndRenderPass(command_buffer);

Answer 1

绘制设置非常复杂，但是绘制所需的实际调用非常简单。从tri.c（绘制2D三角形）：

// ...
vkCmdBeginRenderPass(demo->draw_cmd, &rp_begin, VK_SUBPASS_CONTENTS_INLINE);
vkCmdBindPipeline(demo->draw_cmd, VK_PIPELINE_BIND_POINT_GRAPHICS,
                              demo->pipeline);
vkCmdBindDescriptorSets(demo->draw_cmd, VK_PIPELINE_BIND_POINT_GRAPHICS, demo->pipeline_layout,
        0, 1, & demo->desc_set, 0, NULL);

VkViewport viewport = {};
viewport.height = (float) demo->height;
viewport.width = (float) demo->width;
viewport.minDepth = (float) 0.0f;
viewport.maxDepth = (float) 1.0f;
vkCmdSetViewport(demo->draw_cmd, 0, 1, &viewport);

VkRect2D scissor = {};
scissor.extent.width = demo->width;
scissor.extent.height = demo->height;
scissor.offset.x = 0;
scissor.offset.y = 0;
vkCmdSetScissor(demo->draw_cmd, 0, 1, &scissor);

VkDeviceSize offsets[1] = {0};
vkCmdBindVertexBuffers(demo->draw_cmd, VERTEX_BUFFER_BIND_ID, 1, &demo->vertices.buf, offsets);

vkCmdDraw(demo->draw_cmd, 3, 1, 0, 0);
vkCmdEndRenderPass(demo->draw_cmd);
// ...

此代码段假定您已经获得了VkPipeline（包括着色器等），VkBuffer（用于顶点缓冲区）和VkCommandBufferin适当的状态。这是vkCmdDraw实际发出命令来绘制，一旦含有VkCommandBuffer被执行。