一.简介
纹理映射是一种为三角形赋予图像数据的技术
在 Direct3D 中一个纹理是通过 IDirect3DTexture9 接口来表示,一个纹理是一个像素矩阵的表面被映射到三角形上
二.纹理坐标
Direct3D 使用一个纹理坐标系统,它是由水平方向的 u 轴(向右为正)和竖直方向 v 轴(向下为正)构成
// 纹理坐标系统表示
struct Vertex
{
float _x, _y, _z;
float _nx, _ny, _nz;
float _u, _v;
static const DWORD FVF;};
const DWORD Vertex::FVF = D3DFVF_XYZ | D3DFVF_NORMAL | D3DFVF_TEX1;
三.创建纹理
1.D3DXCreateTextureFromFile()
纹理数据可以从存储在磁盘中的图片文件中读取,放入 IDirect3DTexture9 抽象纹理类型
支持的图片格式有: BMP DDS DIB JPG PNG TGA
HRESULT D3DXCreateTextureFromFile(
LPDIRECT3DDEVICE9 pDevice,
LPCSTR pSrcFile,
LPDIRECT3DTEXTURE9* ppTexture
);
HRESULT IDirect3DDevice9::SetTexture(
DWORD Stage,
IDirect3DBaseTexture9* pTexture
);
// 创建纹理IDirect3Dtexture9* _stonewall;D3DXCreateTextureFromFile(_device, "stonewall.bmp", &_stonewall);// 设置纹理Device->SetTexture(0, _stonewall);
四.过滤器
纹理被映射到屏幕中的三角形上,有可能纹理和三角形不一样大,当出现需要对纹理进行变形的时候,就要用过滤(Filtering)来让变形平滑的技术
Direct3D提供了三种不同的过滤器,每种的品质级别和速度各不相同
1.Nearest point sampling
默认的过滤方法,品质最差,速度最快
Device->SetSamplerState(0, D3DSAMP_MAGFILTER, D3DTEXF_POINT);Device->SetSamplerState(0, D3DSAMP_MINFILTER, D3DTEXF_POINT);
2.Linear filtering
推荐使用,过滤产生的效果好
Device->SetSamplerState(0, D3DSAMP_MAGFILTER, D3DTEXF_LINEAR);Device->SetSamplerState(0, D3DSAMP_MINFILTER, D3DTEXF_LINEAR);
3.Anisotropic filtering
过滤产生的品质最好,处理时间最长
Device->SetSamplerState(0, D3DSAMP_MAGFILTER, D3DTEXF_ANISOTROPIC);Device->SetSamplerState(0, D3DSAMP_MINFILTER, D3DTEXF_ANISOTROPIC);
4.Mipmaps过滤器
如果显卡支持Mipmaps,Direct3D会自动选择与三角形最匹配的Mipmap
Device->SetSamplerState(0, D3DSAMP_MIPFILTER, D3DTEXF_NONE); // 不使用 mipmap Device->SetSamplerState(0, D3DSAMP_MIPFILTER, D3DTEXF_POINT); Device->SetSamplerState(0, D3DSAMP_MIPFILTER, D3DTEXF_LINEAR);
五.寻址模式
纹理坐标必须指定在[0, 1]之间
Direct3D的寻址模式有四种: 环绕纹理寻址模式 边框颜色纹理寻址模式 截取纹理寻址模式 镜像纹理寻址模式
1.环绕纹理寻址模式(wrap address mode)
if (::GetAsyncKeyState('W') & 0x8000f){ Device->SetSamplerState(0, D3DSAMP_ADDRESSU, D3DTADDRESS_WRAP); Device->SetSamplerState(0, D3DSAMP_ADDRESSV, D3DTADDRESS_WRAP); }
2.边框颜色纹理寻址模式(border color address mode)
if (::GetAsyncKeyState('B') & 0x8000f){ Device>SetSamplerState(0, D3DSAMP_ADDRESSU, D3DTADDRESS_BORDER); Device->SetSamplerState(0, D3DSAMP_ADDRESSV, D3DTADDRESS_BORDER); Device->SetSamplerState(0, D3DSAMP_BORDERCOLOR, 0x000000ff);}
3.截取纹理寻址模式(clamp address mode)
if (::GetAsyncKeyState('C') & 0x8000f){ Device->SetSamplerState(0, D3DSAMP_ADDRESSU, D3DTADDRESS_CLAMP); Device->SetSamplerState(0, D3DSAMP_ADDRESSV, D3DTADDRESS_CLAMP);}
4.镜像纹理寻址模式(mirror address mode)
if (::GetAsyncKeyState('M') & 0x8000f){ Device->SetSamplerState(0, D3DSAMP_ADDRESSU, D3DTADDRESS_MIRROR); Device->SetSamplerState(0, D3DSAMP_ADDRESSV, D3DTADDRESS_MIRROR);}
六.例子
1.不过滤纹理
#include "d3dUtility.h"IDirect3DDevice9* Device = 0;const int Width = 640;const int Height = 480;IDirect3DVertexBuffer9* Quad = 0;IDirect3DTexture9* Tex = 0;struct Vertex{ Vertex(){} float _x, _y, _z; float _nx, _ny, _nz; float _u, _v; Vertex(float x, float y, float z, float nx, float ny, float nz, float u, float v) { _x = x; _y = y; _z = z; _nx = nx; _ny = ny; _nz = nz; _u = u; _v = v; } static const DWORD FVF;};const DWORD Vertex::FVF = D3DFVF_XYZ | D3DFVF_NORMAL | D3DFVF_TEX1;bool Setup(){ Device->CreateVertexBuffer( 6 * sizeof(Vertex), D3DUSAGE_WRITEONLY, Vertex::FVF, D3DPOOL_MANAGED, &Quad, 0); Vertex* v; Quad->Lock(0, 0, (void**)&v, 0); v[0] = Vertex(-1.0f, -1.0f, 1.25f, 0.0f, 0.0f, -1.0f, 0.0f, 1.0f); v[1] = Vertex(-1.0f, 1.0f, 1.25f, 0.0f, 0.0f, -1.0f, 0.0f, 0.0f); v[2] = Vertex(1.0f, 1.0f, 1.25f, 0.0f, 0.0f, -1.0f, 1.0f, 0.0f); v[3] = Vertex(-1.0f, -1.0f, 1.25f, 0.0f, 0.0f, -1.0f, 0.0f, 1.0f); v[4] = Vertex(1.0f, 1.0f, 1.25f, 0.0f, 0.0f, -1.0f, 1.0f, 0.0f); v[5] = Vertex(1.0f, -1.0f, 1.25f, 0.0f, 0.0f, -1.0f, 1.0f, 1.0f); Quad->Unlock(); // 加载纹理文件 D3DXCreateTextureFromFile(Device, "a.bmp", &Tex); Device->SetTexture(0, Tex); Device->SetSamplerState(0, D3DSAMP_MAGFILTER, D3DTEXF_LINEAR); Device->SetSamplerState(0, D3DSAMP_MINFILTER, D3DTEXF_LINEAR); Device->SetSamplerState(0, D3DSAMP_MIPFILTER, D3DTEXF_POINT); Device->SetRenderState(D3DRS_LIGHTING, false); D3DXMATRIX proj; D3DXMatrixPerspectiveFovLH( &proj, D3DX_PI * 0.5f, (float)Width / (float)Height, 1.0f, 1000.0f); Device->SetTransform(D3DTS_PROJECTION, &proj); return true;}void Cleanup(){ d3d::Release (Quad); d3d::Release (Tex);}bool Display(float timeDelta){ if (Device) { Device->Clear(0, 0, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, 0xffffffff, 1.0f, 0); Device->BeginScene(); Device->SetStreamSource(0, Quad, 0, sizeof(Vertex)); Device->SetFVF(Vertex::FVF); Device->DrawPrimitive(D3DPT_TRIANGLELIST, 0, 2); Device->EndScene(); Device->Present(0, 0, 0, 0); } return true;}
2.过滤处理纹理
#include "d3dUtility.h"//// Globals//IDirect3DDevice9* Device = 0;const int Width = 640;const int Height = 480;IDirect3DVertexBuffer9* Quad = 0;IDirect3DTexture9* Tex = 0;// 顶点格式struct Vertex{ Vertex(){} Vertex( float x, float y, float z, float nx, float ny, float nz, float u, float v) { _x = x; _y = y; _z = z; _nx = nx; _ny = ny; _nz = nz; _u = u; _v = v; } float _x, _y, _z; float _nx, _ny, _nz; float _u, _v; static const DWORD FVF;};const DWORD Vertex::FVF = D3DFVF_XYZ | D3DFVF_NORMAL | D3DFVF_TEX1;//// Framework Functions//bool Setup(){ // 创建顶点缓存 Device->CreateVertexBuffer( 6 * sizeof(Vertex), D3DUSAGE_WRITEONLY, Vertex::FVF, D3DPOOL_MANAGED, &Quad, 0); Vertex* v; Quad->Lock(0, 0, (void**)&v, 0); v[0] = Vertex(-1.0f, -1.0f, 1.25f, 0.0f, 0.0f, -1.0f, 0.0f, 3.0f); v[1] = Vertex(-1.0f, 1.0f, 1.25f, 0.0f, 0.0f, -1.0f, 0.0f, 0.0f); v[2] = Vertex( 1.0f, 1.0f, 1.25f, 0.0f, 0.0f, -1.0f, 3.0f, 0.0f); v[3] = Vertex(-1.0f, -1.0f, 1.25f, 0.0f, 0.0f, -1.0f, 0.0f, 3.0f); v[4] = Vertex( 1.0f, 1.0f, 1.25f, 0.0f, 0.0f, -1.0f, 3.0f, 0.0f); v[5] = Vertex( 1.0f, -1.0f, 1.25f, 0.0f, 0.0f, -1.0f, 3.0f, 3.0f); Quad->Unlock(); // // Create the texture and set texture // D3DXCreateTextureFromFile( Device, "a.bmp", &Tex); Device->SetTexture(0, Tex); Device->SetSamplerState(0, D3DSAMP_MAGFILTER, D3DTEXF_LINEAR); Device->SetSamplerState(0, D3DSAMP_MINFILTER, D3DTEXF_LINEAR); Device->SetSamplerState(0, D3DSAMP_MIPFILTER, D3DTEXF_POINT); // // Don't use lighting for this sample // Device->SetRenderState(D3DRS_LIGHTING, false); // // Set the projection matrix // D3DXMATRIX proj; D3DXMatrixPerspectiveFovLH( &proj, D3DX_PI * 0.5f, (float)Width / (float)Height, 1.0f, 1000.0f); Device->SetTransform(D3DTS_PROJECTION, &proj); return true;}void Cleanup(){ d3d::Release (Quad); d3d::Release (Tex);}bool Display(float timeDelta){ if (Device) { // // Update the scene // // set wrap address mode if (::GetAsyncKeyState('W') & 0x8000f) { Device->SetSamplerState(0, D3DSAMP_ADDRESSU, D3DTADDRESS_WRAP); Device->SetSamplerState(0, D3DSAMP_ADDRESSV, D3DTADDRESS_WRAP); } // set border color address mode if (::GetAsyncKeyState('B') & 0x8000f) { Device->SetSamplerState(0, D3DSAMP_ADDRESSU, D3DTADDRESS_BORDER); Device->SetSamplerState(0, D3DSAMP_ADDRESSV, D3DTADDRESS_BORDER); Device->SetSamplerState(0, D3DSAMP_BORDERCOLOR, 0x000000ff); } // set clamp address mode if (::GetAsyncKeyState('C') & 0x8000f) { Device->SetSamplerState(0, D3DSAMP_ADDRESSU, D3DTADDRESS_CLAMP); Device->SetSamplerState(0, D3DSAMP_ADDRESSV, D3DTADDRESS_CLAMP); } // set mirror address mode if (::GetAsyncKeyState('M') & 0x8000f) { Device->SetSamplerState(0, D3DSAMP_ADDRESSU, D3DTADDRESS_MIRROR); Device->SetSamplerState(0, D3DSAMP_ADDRESSV, D3DTADDRESS_MIRROR); } // // Draw the scene // Device->Clear(0, 0, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, 0xffffffff, 1.0f, 0); Device->BeginScene(); Device->SetStreamSource(0, Quad, 0, sizeof(Vertex)); Device->SetFVF(Vertex::FVF); Device->DrawPrimitive(D3DPT_TRIANGLELIST, 0, 2); Device->EndScene(); Device->Present(0, 0, 0, 0); } return true;}