Hi everyone,
I am new to DX12, I download sample project from MSDN and it can run and draw triangles successfully.
But when I create new project and copy code from MSDN sample (Hello Triangles Project). I do not know why it could not render anything to screen except clearing the screen with blue color.
Could you have a look at my code to see what problem is... I got stuck here for 2 days.
One thing that stands out to me:
struct Vertex {
XMFLOAT3 position;
XMFLOAT4 color;
};Here you have a float3 for position; which is matched by your input-signature declaration.
PSInput VSMain(float4 position : POSITION, float4 color : COLOR)
{
PSInput result;
result.position = position;
result.color = color;
return result;
}But the Vertex-shader receives a float4. Even if this were technically legal (not sure in DX12), this probably means that the w-component is 0.0f, while it should actually be 1.0f when output from the vertex-shader w/o any persective transform, as is the case for you. I'd suggest trying:
PSInput VSMain(float3 position : POSITION, float4 color : COLOR)
{
PSInput result;
result.position.xyz = position;
result.position.w = 1.0f;
result.color = color;
return result;
and see if this works.
Where are you setting your viewport and scissor rectangle? (m_viewport and m_scissorRect)
This is exactly what happens when you copy from multiple sources and smash it all together without reading things through.
Anyway, it will work once you initialize those
Edit:
Juliean is write about using a float3 instead of a float4. Weird enough though, the w component actually gets default initialized to 1.0f, and as Juliean mentioned you would have assumed it was being zero initialized, this is a good reason to be explicit
First, I want to thank iedoc and Juliean
That was my ridiculous mistake when quickly copy and paste
Actuallly, I was working on a bigger project, porting that project from D3D11 to D3D12 and met such an issue. Do not know why it could not render anything to screen. Because resource is huge, I can not upload it all here.
I am sure that I set m_viewport and m_scissorRect already on that project 
. Here is my work:
- On init: (using commandlist 1, commandAllocator1)
+Create Vertex buffer (default heap and upload heap)
+Execute commandlist
+Sleep(1000): maybe do not need but just to make sure init command was finished on GPU before render.
- On Render: (using commandlist 2, commandAllocator 2, same commandQueue)
+Transition Vertex buffer from COPY_DEST to VERTEX_BUFFER
+Transition backbuffer to PRESENT to RENDER_TARGET
+OMSetRenderTargets
+ClearRendertarget
+SetViewport and scissor (sure it has value)
+SetGraphicsRootSignature and PipelineState (using same root and pipeline as above example because I just want to draw triangle, VertexShader use position as float3 and inputlayout is float3 also)
+IASetVertexBuffers
+IASetPrimitiveTopology
+DrawInstanced
+Transition backbuffer to RENDER_TARGET to PRESENT
+Execute commandlist
+Present()
+Update frame index
- I can see clear color, if I set clear color different each frame and set break point at present(), i can see it changed color each times but no triangles. Could you guys please show me if i miss any step.
Note: Sometimes, I can see that triangles blink at first launch and disappear.
I think I found problem with VertexBuffers, if I use a temp VertexBuffers it can draw. Need more time to investigate, thank you all
Thank you all, problem solved. I forgot the cull mode, using default rasterize state set cullmode to BACK. That make me can not draw anything
