![](/img/trans.png)
[英]How to draw a dotted pattern 3D line with tessellation in DirectX 11?
[英]Is it possible to draw a circle made up of triangles with DirectX 3D 11?
是否可以使用DirectX 3D 11從16個三角形中創建一個圓; 有點像單位圓? 我目前正在使用Direct3D 11教程02:從DirectX示例瀏覽器渲染三角形(2010年6月),並對其進行了一些修改以在中心繪制三角形,但是現在我想使用該三角形繪制一個圓。
我必須創建48個頂點才能創建它,還是有一種更簡單的方法? 就像使用for循環一樣。
我對C ++還是陌生的,只是在學習和習慣它以及DirectX基礎知識。
這是Tutorial02.cpp的代碼:
//--------------------------------------------------------------------------------------
// File: Tutorial02.cpp
//
// This application displays a triangle using Direct3D 11
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//--------------------------------------------------------------------------------------
#include <windows.h>
#include <d3d11.h>
#include <d3dx11.h>
#include <d3dcompiler.h>
#include <xnamath.h>
#include "resource.h"
//--------------------------------------------------------------------------------------
// Structures
//--------------------------------------------------------------------------------------
struct SimpleVertex
{
XMFLOAT3 Pos;
};
//--------------------------------------------------------------------------------------
// Global Variables
//--------------------------------------------------------------------------------------
HINSTANCE g_hInst = NULL;
HWND g_hWnd = NULL;
D3D_DRIVER_TYPE g_driverType = D3D_DRIVER_TYPE_NULL;
D3D_FEATURE_LEVEL g_featureLevel = D3D_FEATURE_LEVEL_11_0;
ID3D11Device* g_pd3dDevice = NULL;
ID3D11DeviceContext* g_pImmediateContext = NULL;
IDXGISwapChain* g_pSwapChain = NULL;
ID3D11RenderTargetView* g_pRenderTargetView = NULL;
ID3D11VertexShader* g_pVertexShader = NULL;
ID3D11PixelShader* g_pPixelShader = NULL;
ID3D11InputLayout* g_pVertexLayout = NULL;
ID3D11Buffer* g_pVertexBuffer = NULL;
//--------------------------------------------------------------------------------------
// Forward declarations
//--------------------------------------------------------------------------------------
HRESULT InitWindow( HINSTANCE hInstance, int nCmdShow );
HRESULT InitDevice();
void CleanupDevice();
LRESULT CALLBACK WndProc( HWND, UINT, WPARAM, LPARAM );
void Render();
//--------------------------------------------------------------------------------------
// Entry point to the program. Initializes everything and goes into a message processing
// loop. Idle time is used to render the scene.
//--------------------------------------------------------------------------------------
int WINAPI wWinMain( HINSTANCE hInstance, HINSTANCE hPrevInstance, LPWSTR lpCmdLine, int nCmdShow )
{
UNREFERENCED_PARAMETER( hPrevInstance );
UNREFERENCED_PARAMETER( lpCmdLine );
if( FAILED( InitWindow( hInstance, nCmdShow ) ) )
return 0;
if( FAILED( InitDevice() ) )
{
CleanupDevice();
return 0;
}
// Main message loop
MSG msg = {0};
while( WM_QUIT != msg.message )
{
if( PeekMessage( &msg, NULL, 0, 0, PM_REMOVE ) )
{
TranslateMessage( &msg );
DispatchMessage( &msg );
}
else
{
Render();
}
}
CleanupDevice();
return ( int )msg.wParam;
}
//--------------------------------------------------------------------------------------
// Register class and create window
//--------------------------------------------------------------------------------------
HRESULT InitWindow( HINSTANCE hInstance, int nCmdShow )
{
// Register class
WNDCLASSEX wcex;
wcex.cbSize = sizeof( WNDCLASSEX );
wcex.style = CS_HREDRAW | CS_VREDRAW;
wcex.lpfnWndProc = WndProc;
wcex.cbClsExtra = 0;
wcex.cbWndExtra = 0;
wcex.hInstance = hInstance;
wcex.hIcon = LoadIcon( hInstance, ( LPCTSTR )IDI_TUTORIAL1 );
wcex.hCursor = LoadCursor( NULL, IDC_ARROW );
wcex.hbrBackground = ( HBRUSH )( COLOR_WINDOW + 1 );
wcex.lpszMenuName = NULL;
wcex.lpszClassName = L"TutorialWindowClass";
wcex.hIconSm = LoadIcon( wcex.hInstance, ( LPCTSTR )IDI_TUTORIAL1 );
if( !RegisterClassEx( &wcex ) )
return E_FAIL;
// Create window
g_hInst = hInstance;
RECT rc = { 0, 0, 640, 480 };
AdjustWindowRect( &rc, WS_OVERLAPPEDWINDOW, FALSE );
g_hWnd = CreateWindow( L"TutorialWindowClass", L"Direct3D 11 Tutorial 2: Rendering a Triangle",
WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, CW_USEDEFAULT, rc.right - rc.left, rc.bottom - rc.top, NULL, NULL, hInstance,
NULL );
if( !g_hWnd )
return E_FAIL;
ShowWindow( g_hWnd, nCmdShow );
return S_OK;
}
//--------------------------------------------------------------------------------------
// Helper for compiling shaders with D3DX11
//--------------------------------------------------------------------------------------
HRESULT CompileShaderFromFile( WCHAR* szFileName, LPCSTR szEntryPoint, LPCSTR szShaderModel, ID3DBlob** ppBlobOut )
{
HRESULT hr = S_OK;
DWORD dwShaderFlags = D3DCOMPILE_ENABLE_STRICTNESS;
#if defined( DEBUG ) || defined( _DEBUG )
// Set the D3DCOMPILE_DEBUG flag to embed debug information in the shaders.
// Setting this flag improves the shader debugging experience, but still allows
// the shaders to be optimized and to run exactly the way they will run in
// the release configuration of this program.
dwShaderFlags |= D3DCOMPILE_DEBUG;
#endif
ID3DBlob* pErrorBlob;
hr = D3DX11CompileFromFile( szFileName, NULL, NULL, szEntryPoint, szShaderModel,
dwShaderFlags, 0, NULL, ppBlobOut, &pErrorBlob, NULL );
if( FAILED(hr) )
{
if( pErrorBlob != NULL )
OutputDebugStringA( (char*)pErrorBlob->GetBufferPointer() );
if( pErrorBlob ) pErrorBlob->Release();
return hr;
}
if( pErrorBlob ) pErrorBlob->Release();
return S_OK;
}
//--------------------------------------------------------------------------------------
// Create Direct3D device and swap chain
//--------------------------------------------------------------------------------------
HRESULT InitDevice()
{
HRESULT hr = S_OK;
RECT rc;
GetClientRect( g_hWnd, &rc );
UINT width = rc.right - rc.left;
UINT height = rc.bottom - rc.top;
UINT createDeviceFlags = 0;
#ifdef _DEBUG
createDeviceFlags |= D3D11_CREATE_DEVICE_DEBUG;
#endif
D3D_DRIVER_TYPE driverTypes[] =
{
D3D_DRIVER_TYPE_HARDWARE,
D3D_DRIVER_TYPE_WARP,
D3D_DRIVER_TYPE_REFERENCE,
};
UINT numDriverTypes = ARRAYSIZE( driverTypes );
D3D_FEATURE_LEVEL featureLevels[] =
{
D3D_FEATURE_LEVEL_11_0,
D3D_FEATURE_LEVEL_10_1,
D3D_FEATURE_LEVEL_10_0,
};
UINT numFeatureLevels = ARRAYSIZE( featureLevels );
DXGI_SWAP_CHAIN_DESC sd;
ZeroMemory( &sd, sizeof( sd ) );
sd.BufferCount = 1;
sd.BufferDesc.Width = width;
sd.BufferDesc.Height = height;
sd.BufferDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
sd.BufferDesc.RefreshRate.Numerator = 60;
sd.BufferDesc.RefreshRate.Denominator = 1;
sd.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;
sd.OutputWindow = g_hWnd;
sd.SampleDesc.Count = 1;
sd.SampleDesc.Quality = 0;
sd.Windowed = TRUE;
for( UINT driverTypeIndex = 0; driverTypeIndex < numDriverTypes; driverTypeIndex++ )
{
g_driverType = driverTypes[driverTypeIndex];
hr = D3D11CreateDeviceAndSwapChain( NULL, g_driverType, NULL, createDeviceFlags, featureLevels, numFeatureLevels,
D3D11_SDK_VERSION, &sd, &g_pSwapChain, &g_pd3dDevice, &g_featureLevel, &g_pImmediateContext );
if( SUCCEEDED( hr ) )
break;
}
if( FAILED( hr ) )
return hr;
// Create a render target view
ID3D11Texture2D* pBackBuffer = NULL;
hr = g_pSwapChain->GetBuffer( 0, __uuidof( ID3D11Texture2D ), ( LPVOID* )&pBackBuffer );
if( FAILED( hr ) )
return hr;
hr = g_pd3dDevice->CreateRenderTargetView( pBackBuffer, NULL, &g_pRenderTargetView );
pBackBuffer->Release();
if( FAILED( hr ) )
return hr;
g_pImmediateContext->OMSetRenderTargets( 1, &g_pRenderTargetView, NULL );
// Setup the viewport
D3D11_VIEWPORT vp;
vp.Width = (FLOAT)width;
vp.Height = (FLOAT)height;
vp.MinDepth = 0.0f;
vp.MaxDepth = 1.0f;
vp.TopLeftX = 0;
vp.TopLeftY = 0;
g_pImmediateContext->RSSetViewports( 1, &vp );
// Compile the vertex shader
ID3DBlob* pVSBlob = NULL;
hr = CompileShaderFromFile( L"Tutorial02.fx", "VS", "vs_4_0", &pVSBlob );
if( FAILED( hr ) )
{
MessageBox( NULL,
L"The FX file cannot be compiled. Please run this executable from the directory that contains the FX file.", L"Error", MB_OK );
return hr;
}
// Create the vertex shader
hr = g_pd3dDevice->CreateVertexShader( pVSBlob->GetBufferPointer(), pVSBlob->GetBufferSize(), NULL, &g_pVertexShader );
if( FAILED( hr ) )
{
pVSBlob->Release();
return hr;
}
// Define the input layout
D3D11_INPUT_ELEMENT_DESC layout[] =
{
{ "POSITION", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0, 0, D3D11_INPUT_PER_VERTEX_DATA, 0 },
};
UINT numElements = ARRAYSIZE( layout );
// Create the input layout
hr = g_pd3dDevice->CreateInputLayout( layout, numElements, pVSBlob->GetBufferPointer(),
pVSBlob->GetBufferSize(), &g_pVertexLayout );
pVSBlob->Release();
if( FAILED( hr ) )
return hr;
// Set the input layout
g_pImmediateContext->IASetInputLayout( g_pVertexLayout );
// Compile the pixel shader
ID3DBlob* pPSBlob = NULL;
hr = CompileShaderFromFile( L"Tutorial02.fx", "PS", "ps_4_0", &pPSBlob );
if( FAILED( hr ) )
{
MessageBox( NULL,
L"The FX file cannot be compiled. Please run this executable from the directory that contains the FX file.", L"Error", MB_OK );
return hr;
}
// Create the pixel shader
hr = g_pd3dDevice->CreatePixelShader( pPSBlob->GetBufferPointer(), pPSBlob->GetBufferSize(), NULL, &g_pPixelShader );
pPSBlob->Release();
if( FAILED( hr ) )
return hr;
// Create vertex buffer
SimpleVertex vertices[] =
{
XMFLOAT3(-0.1f, 0.8f, 0.5f),
XMFLOAT3(0.1f, 0.8f, 0.5f),
XMFLOAT3(0.0f, 0.0f, 0.5f),
};
D3D11_BUFFER_DESC bd;
ZeroMemory( &bd, sizeof(bd) );
bd.Usage = D3D11_USAGE_DEFAULT;
bd.ByteWidth = sizeof( SimpleVertex ) * 3;
bd.BindFlags = D3D11_BIND_VERTEX_BUFFER;
bd.CPUAccessFlags = 0;
D3D11_SUBRESOURCE_DATA InitData;
ZeroMemory( &InitData, sizeof(InitData) );
InitData.pSysMem = vertices;
hr = g_pd3dDevice->CreateBuffer( &bd, &InitData, &g_pVertexBuffer );
if( FAILED( hr ) )
return hr;
// Set vertex buffer
UINT stride = sizeof( SimpleVertex );
UINT offset = 0;
g_pImmediateContext->IASetVertexBuffers( 0, 1, &g_pVertexBuffer, &stride, &offset );
// Set primitive topology
g_pImmediateContext->IASetPrimitiveTopology( D3D11_PRIMITIVE_TOPOLOGY_TRIANGLELIST );
return S_OK;
}
//--------------------------------------------------------------------------------------
// Clean up the objects we've created
//--------------------------------------------------------------------------------------
void CleanupDevice()
{
if( g_pImmediateContext ) g_pImmediateContext->ClearState();
if( g_pVertexBuffer ) g_pVertexBuffer->Release();
if( g_pVertexLayout ) g_pVertexLayout->Release();
if( g_pVertexShader ) g_pVertexShader->Release();
if( g_pPixelShader ) g_pPixelShader->Release();
if( g_pRenderTargetView ) g_pRenderTargetView->Release();
if( g_pSwapChain ) g_pSwapChain->Release();
if( g_pImmediateContext ) g_pImmediateContext->Release();
if( g_pd3dDevice ) g_pd3dDevice->Release();
}
//--------------------------------------------------------------------------------------
// Called every time the application receives a message
//--------------------------------------------------------------------------------------
LRESULT CALLBACK WndProc( HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam )
{
PAINTSTRUCT ps;
HDC hdc;
switch( message )
{
case WM_PAINT:
hdc = BeginPaint( hWnd, &ps );
EndPaint( hWnd, &ps );
break;
case WM_DESTROY:
PostQuitMessage( 0 );
break;
default:
return DefWindowProc( hWnd, message, wParam, lParam );
}
return 0;
}
//--------------------------------------------------------------------------------------
// Render a frame
//--------------------------------------------------------------------------------------
void Render()
{
// Clear the back buffer
float ClearColor[4] = { 0.0f, 0.125f, 0.3f, 1.0f }; // red,green,blue,alpha
g_pImmediateContext->ClearRenderTargetView( g_pRenderTargetView, ClearColor );
// Render a triangle
g_pImmediateContext->VSSetShader( g_pVertexShader, NULL, 0 );
g_pImmediateContext->PSSetShader( g_pPixelShader, NULL, 0 );
g_pImmediateContext->Draw( 3, 0 );
// Present the information rendered to the back buffer to the front buffer (the screen)
g_pSwapChain->Present( 0, 0 );
}
如果要使用16個三角形畫一個圓,則需要17個頂點。 一個用於圓的每個角,另一個用於圓心。 然后,您必須使用48個索引來告訴D3D如何連接這些頂點。 然后,您可以調用DrawIndexed繪制三角形。 您也可以使用三角帶,它是一種不同的原始拓撲,並且使用的索引要少一些。 有關如何創建頂點和索引緩沖區的信息,請參見本教程 。
如您所說,使用for
循環。 假設您要10個三角形。 圓中有2pi弧度,因此每個三角形的角度為2pi / 10。 讓我們計算一下:
int n = 10; // number of triangles
SimpleVertex* vertices = malloc(sizeof(SimpleVertex) * 10 * 3); // 10 triangles, 3 verticies per triangle
float deltaTheta = 2*pi / n; // Change in theta for each vertex
for( int i = 0; i < n; i++ ) {
int theta = i * deltaTheta; // Theta is the angle for that triangle
int index = 3 * i;
vertices[index + 0] = SimpleVertex(0, 0, 0);
// Given an angle theta, cosine [cos] will give you the x coordinate,
// and sine [sin] will give you the y coordinate.
// #include <math.h>
vertices[index + 1] = SimpleVertex(cos(theta), sin(theta), 0);
vertices[index + 2] = SimpleVertex(cos(theta + deltaTheta), sin(theta + deltaTheta), 0);
}
注意:
可以想象,許多頂點將重疊。 (0,0,0)始終相同,並且一個三角形的最后一個頂點等於下一個三角形的第二個垂直方向。 我將讓您進行優化,首先使其開始工作,以便您了解正在發生的事情。 如果您不熟悉Trig,請查找單位圓。 或者只是接受將cos / sin定義為給定度數(或弧度)的圓的x和y坐標。 您將不得不等到您的教程繼續學習如何指定每個三角形首先使用的頂點。
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.