Minimal D3D11 bonus material: extra minimal triangle

.readme.md

Minimal D3D11 bonus material: extra minimal triangle

A quick side exercise to see how little code one can get away with to put that RGB triangle on screen using D3D11 (without bending over backwards with trickery). This is a complete app in < 40 LOC (including the HLSL).

For more.. elaborate.. D3D11 reference code, see the original Minimal D3D11, Minimal D3D11 pt2 and Minimal D3D11 pt3

cpu.cpp

#pragma comment(lib, "user32")
#pragma comment(lib, "d3d11")
#pragma comment(lib, "d3dcompiler")

#include <windows.h>
#include <d3d11.h>
#include <d3dcompiler.h>

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShowCmd)
{
    IDXGISwapChain* swapchain;
    ID3D11Device* device;
    ID3D11DeviceContext* devicecontext;
    ID3D11Texture2D* rendertarget;
    ID3D11RenderTargetView* rendertargetview;
    ID3DBlob* cso;
    ID3D11VertexShader* vertexshader;
    ID3D11PixelShader* pixelshader;
    WNDCLASSA wndclass = { 0, DefWindowProcA, 0, 0, 0, 0, 0, 0, 0, "d7" };
    RegisterClassA(&wndclass);
    DXGI_SWAP_CHAIN_DESC swapchaindesc = { { 0, 0, {}, DXGI_FORMAT_R8G8B8A8_UNORM }, { 1 }, 32, 2, CreateWindowExA(0, "d7", 0, 0x91000000, 0, 0, 0, 0, 0, 0, 0, 0), 1 };
    D3D11CreateDeviceAndSwapChain(0, D3D_DRIVER_TYPE_HARDWARE, 0, 0, 0, 0, 7, &swapchaindesc, &swapchain, &device, 0, &devicecontext);
    swapchain->GetDesc(&swapchaindesc);
    swapchain->GetBuffer(0, __uuidof(ID3D11Texture2D), (void**)&rendertarget);
    device->CreateRenderTargetView(rendertarget, 0, &rendertargetview);
    D3DCompileFromFile(L"gpu.hlsl", 0, 0, "vertex_shader", "vs_5_0", 0, 0, &cso, 0);
    device->CreateVertexShader(cso->GetBufferPointer(), cso->GetBufferSize(), 0, &vertexshader);
    D3DCompileFromFile(L"gpu.hlsl", 0, 0, "pixel_shader", "ps_5_0", 0, 0, &cso, 0);
    device->CreatePixelShader(cso->GetBufferPointer(), cso->GetBufferSize(), 0, &pixelshader);
    D3D11_VIEWPORT viewport = { 0, 0, (float)swapchaindesc.BufferDesc.Width, (float)swapchaindesc.BufferDesc.Height, 0, 1 };
    devicecontext->IASetPrimitiveTopology(D3D11_PRIMITIVE_TOPOLOGY_TRIANGLELIST);
    devicecontext->VSSetShader(vertexshader, 0, 0);
    devicecontext->RSSetViewports(1, &viewport);
    devicecontext->PSSetShader(pixelshader, 0, 0);
    devicecontext->OMSetRenderTargets(1, &rendertargetview, 0);
    devicecontext->Draw(3, 0);
    swapchain->Present(1, 0);
    GetMessageA((MSG*)WinMain, 0, WM_KEYFIRST, WM_KEYLAST); // PRESS ANY KEY TO EXIT
}

gpu.hlsl

struct vertex { float4 pos : SV_POSITION; float4 col : COL; };

vertex vertex_shader(uint vid : SV_VERTEXID)
{ 
    vertex output = { float4(vid * 0.5f, vid & 1, 1, 1.5f) - 0.5f, float4(vid == 0, vid == 1, vid == 2, 1) };
    return output;
}

float4 pixel_shader(vertex input) : SV_TARGET 
{ 
    return input.col;
}

For anyone else who runs into the issue where the window doesn't open, ensure that gpu.hlsl is in the current working directory.