多重纹理理论不作介绍，我也不清楚底层实现，nehe的opengl教程中也有示例。毕业课题中涉及多重纹理的使用，我只是粘贴部分实现代码，对于一些人来说，这已经足够了，：）
我的显卡是gf5700，查询arb扩展，最多支持4个纹理，所以每个pass也就最多加载4个纹理，我把纹理送入显卡，由Cg操纵纹理，所以，下边代码没有过多对纹理的操作，
#include <gl/gl.h>
#include <gl/glu.h>
#include "gl/glext.h" //glext.h需要另外去下载
//定义extensions入口宏
#define INIT_ENTRY_POINT( funcname, type ) static type funcname= (type) wglGetProcAddress(#funcname); if ( !funcname ){ TRACE2(_T("!! Fail to Get Proc address: "#funcname " (%s,%d)\n"),__FILE__,__LINE__); } //Mac end
，，，
//检测一下显卡对多重纹理的支持情况
int nUnits,nSize;
glGetIntegerv(GL_MAX_TEXTURE_UNITS_ARB, &nUnits);
glGetIntegerv(GL_MAX_RECTANGLE_TEXTURE_SIZE_NV, &nSize);
TRACE2("GL_MAX_TEXTURE_UNITS_ARB =%d ,GL_MAX_RECTANGLE_TEXTURE_SIZE_NV =%d \n",nUnits,nSize);
定义纹理，我在里边使用了矩形纹理，这样纹理坐标的范围就不是[0,1],而是[0,w],[0,h],它的使用也很简单，以后有空在说一些它的东西，
glGenTextures(1,¶m.nVerTex);
glBindTexture(GL_TEXTURE_RECTANGLE_NV,param.nVerTex);
glTexImage2D(GL_TEXTURE_RECTANGLE_NV,0,GL_RGB, param.sizeVertexTex.cx, param.sizeVertexTex.cy,0,GL_RGB,GL_FLOAT,param.pfVertexTex);
glTexParameteri(GL_TEXTURE_RECTANGLE_NV,GL_TEXTURE_MAG_FILTER,GL_NEAREST);
glTexParameteri(GL_TEXTURE_RECTANGLE_NV,GL_TEXTURE_MIN_FILTER,GL_NEAREST);
glTexParameteri(GL_TEXTURE_RECTANGLE_NV,GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_RECTANGLE_NV,GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
，，，
创建物体，贴上纹理,
INIT_ENTRY_POINT(
glActiveTextureARB, PFNGLACTIVETEXTUREARBPROC );
INIT_ENTRY_POINT(
glMultiTexCoord2fARB, PFNGLMULTITEXCOORD2FARBPROC );
//绑定纹理
glActiveTextureARB(GL_TEXTURE0_ARB);
glEnable(GL_TEXTURE_RECTANGLE_NV);
glBindTexture(GL_TEXTURE_RECTANGLE_NV,pTexA->nIdxTex);
glActiveTextureARB(GL_TEXTURE1_ARB);
glEnable(GL_TEXTURE_RECTANGLE_NV);
glBindTexture(GL_TEXTURE_RECTANGLE_NV,pTexA->nVerTex);
glActiveTextureARB(GL_TEXTURE2_ARB);
glEnable(GL_TEXTURE_RECTANGLE_NV);
glBindTexture(GL_TEXTURE_RECTANGLE_NV,pTexB->nIdxTex);
glActiveTextureARB(GL_TEXTURE3_ARB);
glEnable(GL_TEXTURE_RECTANGLE_NV);
glBindTexture(GL_TEXTURE_RECTANGLE_NV,pTexB->nVerTex);
glBegin(GL_QUADS);
//左下
glMultiTexCoord2fARB(GL_TEXTURE0_ARB,0,0);
glMultiTexCoord2fARB(GL_TEXTURE1_ARB,0,0);
glMultiTexCoord2fARB(GL_TEXTURE2_ARB,0,0);
glMultiTexCoord2fARB(GL_TEXTURE3_ARB,0,0);
glVertex3f(0.0f,0.0f,-10.0f);
//右下
glMultiTexCoord2fARB(GL_TEXTURE0_ARB,50,0);
glMultiTexCoord2fARB(GL_TEXTURE1_ARB,100.0f,0.0f);
glMultiTexCoord2fARB(GL_TEXTURE2_ARB,10.0f,0.0f);
glMultiTexCoord2fARB(GL_TEXTURE3_ARB,10.0f,0.0f);
glVertex3f(100.0f,0.0f,-10.0f);
//右上
glMultiTexCoord2fARB(GL_TEXTURE0_ARB,50,50);
glMultiTexCoord2fARB(GL_TEXTURE1_ARB,10.0f,10.0f);
glMultiTexCoord2fARB(GL_TEXTURE2_ARB,10.0f,1.0f);
glMultiTexCoord2fARB(GL_TEXTURE3_ARB,10.0f,1.0f);
glVertex3f(100.0f,100.0f,-10.0f);
//左上
glMultiTexCoord2fARB(GL_TEXTURE0_ARB,0,50);
glMultiTexCoord2fARB(GL_TEXTURE1_ARB,0.0f,10.0f);
glMultiTexCoord2fARB(GL_TEXTURE2_ARB,0.0f,10.0f);
glMultiTexCoord2fARB(GL_TEXTURE3_ARB,0.0f,10.0f);
glVertex3f(0.0f,100.0f,-10.0f);
glEnd();
glFlush();
glActiveTextureARB(GL_TEXTURE0_ARB);
glDisable(GL_TEXTURE_RECTANGLE_NV);
glActiveTextureARB(GL_TEXTURE1_ARB);
glDisable(GL_TEXTURE_RECTANGLE_NV);
glActiveTextureARB(GL_TEXTURE2_ARB);
glDisable(GL_TEXTURE_RECTANGLE_NV);
glActiveTextureARB(GL_TEXTURE3_ARB);
glDisable(GL_TEXTURE_RECTANGLE_NV);