本文共 4365 字，大约阅读时间需要 14 分钟。

需准备一张.tga纹理

// The TexturedIdentity Shader// Vertex Shader// Richard S. Wright Jr.// OpenGL SuperBible#version 130in vec4 vVertex;in vec2 vTexCoords;smooth out vec2 vVaryingTexCoords;void main(void)     {     vVaryingTexCoords = vTexCoords;    gl_Position = vVertex;    }

vTexCoords存储了纹理s和t坐标，作为输入，然后插值输出到片段着色器 

// The TexturedIdentity Shader// Fragment Shader// Richard S. Wright Jr.// OpenGL SuperBible#version 130uniform sampler2D colorMap;out vec4 vFragColor;smooth in vec2 vVaryingTexCoords;void main(void)   {    vFragColor = texture(colorMap, vVaryingTexCoords.st);   }

texture(纹理，纹理坐标vec2)得到vec4 颜色值。sampler2D采样器类型，实际上是一个整数值，在GL代码用glUniform1i设定了一个整数值0，代表纹理单元0，即第一个纹理贴图。

// TexturedTriangle.cpp// Our first OpenGL program that will just draw a triangle on the screen.#pragma comment(lib, "gltools.lib")#include 
   
                // OpenGL toolkit#include 
    
         // Shader Manager Class#ifdef __APPLE__#include 
     
                // OS X version of GLUT#else#define FREEGLUT_STATIC#include 
      
                   // Windows FreeGlut equivalent#endifGLBatch	triangleBatch;GLShaderManager	shaderManager;GLint	myTexturedIdentityShader;GLuint	textureID;///// Window has changed size, or has just been created. In either case, we need// to use the window dimensions to set the viewport and the projection matrix.void ChangeSize(int w, int h){	glViewport(0, 0, w, h);}// Load a TGA as a 2D Texture. Completely initialize the statebool LoadTGATexture(const char *szFileName, GLenum minFilter, GLenum magFilter, GLenum wrapMode){	GLbyte *pBits;	int nWidth, nHeight, nComponents;	GLenum eFormat;	// Read the texture bits	pBits = gltReadTGABits(szFileName, &nWidth, &nHeight, &nComponents, &eFormat);	if (pBits == NULL)		return false;	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, wrapMode);	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, wrapMode);	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, minFilter);	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, magFilter);	glPixelStorei(GL_UNPACK_ALIGNMENT, 1);	glTexImage2D(GL_TEXTURE_2D, 0, nComponents, nWidth, nHeight, 0,		eFormat, GL_UNSIGNED_BYTE, pBits);	free(pBits);	if (minFilter == GL_LINEAR_MIPMAP_LINEAR ||		minFilter == GL_LINEAR_MIPMAP_NEAREST ||		minFilter == GL_NEAREST_MIPMAP_LINEAR ||		minFilter == GL_NEAREST_MIPMAP_NEAREST)		glGenerateMipmap(GL_TEXTURE_2D);	return true;}///// This function does any needed initialization on the rendering context. // This is the first opportunity to do any OpenGL related tasks.void SetupRC(){	// Blue background	glClearColor(0.0f, 0.0f, 0.0f, 1.0f);	shaderManager.InitializeStockShaders();	// Load up a triangle	GLfloat vVerts[] = { -0.5f, 0.0f, 0.0f,						  0.5f, 0.0f, 0.0f,						  0.0f, 0.5f, 0.0f };	GLfloat vTexCoords[] = { 0.0f, 0.0f,							  1.0f, 0.0f,							  0.5f, 1.0f };	triangleBatch.Begin(GL_TRIANGLES, 3, 1);	triangleBatch.CopyVertexData3f(vVerts);	triangleBatch.CopyTexCoordData2f(vTexCoords, 0);	triangleBatch.End();	myTexturedIdentityShader = gltLoadShaderPairWithAttributes("TexturedIdentity.vp", "TexturedIdentity.fp", 2,		GLT_ATTRIBUTE_VERTEX, "vVertex", GLT_ATTRIBUTE_TEXTURE0, "vTexCoords");	glGenTextures(1, &textureID);	glBindTexture(GL_TEXTURE_2D, textureID);	LoadTGATexture("stone.tga", GL_LINEAR, GL_LINEAR, GL_CLAMP_TO_EDGE);}///// Cleanupvoid ShutdownRC(){	glDeleteProgram(myTexturedIdentityShader);	glDeleteTextures(1, &textureID);}///// Called to draw scenevoid RenderScene(void){	// Clear the window with current clearing color	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);	glUseProgram(myTexturedIdentityShader);	glBindTexture(GL_TEXTURE_2D, textureID);	GLint iTextureUniform = glGetUniformLocation(myTexturedIdentityShader, "colorMap");	glUniform1i(iTextureUniform, 0);	triangleBatch.Draw();	// Perform the buffer swap to display back buffer	glutSwapBuffers();}///// Main entry point for GLUT based programsint main(int argc, char* argv[]){	gltSetWorkingDirectory(argv[0]);	glutInit(&argc, argv);	glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH | GLUT_STENCIL);	glutInitWindowSize(800, 600);	glutCreateWindow("Textured Triangle");	glutReshapeFunc(ChangeSize);	glutDisplayFunc(RenderScene);	GLenum err = glewInit();	if (GLEW_OK != err) {		fprintf(stderr, "GLEW Error: %s\n", glewGetErrorString(err));		return 1;	}	SetupRC();	glutMainLoop();	ShutdownRC();	return 0;}