I had try to read FrameGraph-Example

[FuXiii]

Hello, it's me again~
The FrameGraph-Example project was amazing. the PBR, IBL and even the Global Illumination. I am just a fresh hand in Computer Graph. How did you learn this knowledge about the Computer Graph? I also want learn them but I don't know where to start it. I just know how to use Vulkan to render a 3D model and skybox. such like vkRenderPass,Subpass and vkGraphicsPipeline etc, But I don't know how to put them together in to FrameGraph. Such like how to design the Material and Mesh class and combine Vulkan with FrameGraph, can you give me some advice or recommended learning path.

[skaarj1989]

I have been playing with graphics programming for 2 years (last December I started to use Vulkan).
I made tons of mistakes (I still do) and rewritten my "game engine" countless times.

You have to understand (and accept) the fact that you can not write/design the perfect (or even good) solution on your first attempt.

Just do not give up, code, experiment and enjoy it.

I can recommend you the following discord servers:

• GraphicsProgramming
• Vulkan

[FuXiii]

Thank you~
I had joined into GraphicsProgramming discussion group and the Vulkan url link I can not open it.
I had found the document about GraphicsProgramming in https://graphics-programming.org/

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In FrameGraph-Example project, When I read void GBufferPass::addGeometryPass(...) function in GBufferPass.cpp:

for (const auto &renderable : renderables) {
        auto &[mesh, subMeshIndex, material, flags, modelMatrix, _] =
          *renderable;

        rc.setGraphicsPipeline(_getPipeline(*mesh.vertexFormat, &material))
          .bindUniformBuffer(0, getBuffer(resources, frameBlock));

        _setTransform(*camera, modelMatrix);
        for (uint32_t unit{kFirstFreeTextureBinding};
             const auto &[_, texture] : material.getDefaultTextures()) {
          rc.bindTexture(unit++, *texture);
        }
        rc.setUniform1i("u_MaterialFlags", flags)
          .draw(*mesh.vertexBuffer, *mesh.indexBuffer,
                mesh.subMeshes[subMeshIndex].geometryInfo);
      }

It will draw all the visible and opaque renderable object.

Is that means all the renderable object will rendering in FrameGraph::PassNode::Execute()?

---

If all the rendering will in FrameGraph::PassNode::Execute(), If in sence there have two object one is cube and another is sphere. just render them. and the FrameGraph is simple:

in SimpleDrawPass::Execute() can I write it like this?:

SimpleDrawPass:::Execute()
{
        vkFrameBuffer fb = {renderTarget, depthImage};
        vkCmdBeginRenderPass(fb,...);
        ...
        vkCmdDraw(cube);
        ...
        vkCmdDraw(sphere);
        vkCmdEndRenderPass()
        
        CmdBufferSubmitToQueue(cmdBuffer);   
}

Is that means a PassNode in FrameGraph is an vkRenderPass?

If the FrameGraph like this:

the SimpleDrawPass::Execute() similar as above.

SimpleDrawPass:::Execute()
{
        vkFrameBuffer fb = {colorImage, depthImage};
        vkCmdBeginRenderPass(fb,...);
        ...
        vkCmdDraw(cube);
        ...
        vkCmdDraw(sphere);
        vkCmdEndRenderPass()
        
        CmdBufferSubmitToQueue(cmdBuffer);   
}

but the SamplePass::Execute() maybe looks like:

SamplePass:::Execute()
{
        vkFrameBuffer fb = {colorImage, depthImage, renderTarget};
        vkCmdBeginRenderPass(fb,...);
        ...
        vkCmdDraw(wholeSurface);//sample from colorImage or depthImage into renderTarget, such like use input attachment
        vkCmdEndRenderPass()
        
        CmdBufferSubmitToQueue(cmdBuffer);   
}

In this case we did't use Subpass feature. But normally, use Subpass these can be combined into one commandBuffer such like:

vkFrameBuffer fb = {colorImage, depthImage, renderTarget};
vkCmdBeginRenderPass(fb,...);
...
vkCmdDraw(cube);
...
vkCmdDraw(sphere);

vkCmdNextSubpass();
...
vkCmdDraw(wholeSurface);//sample from colorImage or depthImage into renderTarget, such like use input attachment
vkCmdEndRenderPass()
        
CmdBufferSubmitToQueue(cmdBuffer);   

this means a FrameGraph become a RenderPass,and PassNode become Subpass. Is that right?How to elegent combine PassNode, RenderPass and Subpass?

---

Can you share how to learn Global Illumination? Thanks~

[skaarj1989]

In my Vulkan RHI I use VK_KHR_dynamic_rendering (which means I do not need VkRenderPass and VkFramebuffer).

Global Illumination overview: https://morgan3d.github.io/articles/2019-04-01-ddgi/overview.html

[FuXiii]

Yes, if the device support vulkan 1.3 the VK_KHR_dynamic_rendering will be fine, but in some vender's physical device they only support vulkan 1.0. o(╥﹏╥)o~

[FuXiii]

in Global Illumination overview. Is this GI implemented using ray tracing？such like use VK_NV_ray_tracing in vulkan by NVIDIA GPU card or VK_KHR_ray_tracing_pipeline?