#include <GLUT/GLUT.h>

 GLsizei winWidht = , winHeight = ;

 void init (void)

 {

     glClearColor(1.0, 1.0, 1.0, 0.0);

     glMatrixMode(GL_PROJECTION);

     glLoadIdentity();

     gluOrtho2D(-, , -, );

 }

 void xyCoords (void)

 {

     glBegin(GL_LINES);

     glColor3f(0.0, 0.0, 0.0);

     glVertex2i(-, );

     glVertex2i(, );

     glVertex2i(, -);

     glVertex2i(, );

     glEnd();

 }

 void lineTextureMapping (void)

 {

     GLint k;

     GLubyte texLine [];

     for (k = ; k <= ; k +=) {

         texLine [*k] = ;

         texLine [*k+] = ;

         texLine [*k+] = ;

         texLine [*k+] = ;

     }

     for (k = ; k <= ; k +=) {

         texLine [*k] = ;

         texLine [*k+] = ;

         texLine [*k+] = ;

         texLine [*k+] = ;

     }

     glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

     glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);

     glTexImage1D(GL_TEXTURE_1D, , GL_RGBA, , , GL_RGBA, GL_UNSIGNED_BYTE, texLine);

     glEnable(GL_TEXTURE_1D);

     glColor3f(1.0, 1.0, 1.0);

     glBegin(GL_LINES);

     glTexCoord1f(0.25);

     glVertex2f(-4.5, 4.0);

     glTexCoord1f(1.0);

     glVertex2f(-4.5, -4.0);

     glEnd();

     glDisable(GL_TEXTURE_1D);

 }

 void surfaceTextureMapping (void)

 {

     GLint k, j;

     GLubyte texArray [][][];

     for (k = ; k < ; k++) {

         for (j = ; j < ; j++) {

             texArray [k][j][] =  - k*j/;

             texArray [k][j][] =  + k*j/;

             texArray [k][j][] = ;

             texArray [k][j][] = ;

         }

     }

     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);

     glTexImage2D(GL_TEXTURE_2D, , GL_RGBA, , , , GL_RGBA, GL_UNSIGNED_BYTE, texArray);

     glEnable(GL_TEXTURE_2D);

     glColor3f(0.5, 0.5, 0.5); // 与纹理值相乘，因此会发暗

     glBegin(GL_QUADS);

     glTexCoord2f(0.0, 0.0);

     glVertex2f(0.0, 0.0);

     glTexCoord2f(3.0, 0.0);

     glVertex2f(3.0, 0.0);

     glTexCoord2f(3.0, 3.0);

     glVertex2f(3.0, 3.0);

     glTexCoord2f(0.0, 3.0);

     glVertex2f(0.0, 3.0);

     glEnd();

     glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);

     glColor3f(0.5, 0.5, 0.5); // 替换为纹理颜色，则不会像前一个图案那样发暗

     glBegin(GL_QUADS);

     glTexCoord2f(0.0, 0.0);

     glVertex2f(-4.0, -4.0);

     glTexCoord2f(1.0, 0.0);

     glVertex2f(-1.0, -4.0);

     glTexCoord2f(1.0, 1.0);

     glVertex2f(-1.0, -1.0);

     glTexCoord2f(0.0, 1.0);

     glVertex2f(-4.0, -1.0);

     glEnd();

     glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);

     // 不允许纹理坐标超过1，因此小于0的设为0，大于1的设为1

     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);

     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);

     glColor3f(1.0, 1.0, 1.0);

     glBegin(GL_QUADS);

     glTexCoord2f(0.0, 0.0);

     glVertex2f(-4.0, 0.0);

     glTexCoord2f(, 0.0);

     glVertex2f(-1.0, 0.0);

     glTexCoord2f(, );

     glVertex2f(-1.0, 3.0);

     glTexCoord2f(0.0, );

     glVertex2f(-4.0, 3.0);

     glEnd();

     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);

     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);

     glDisable(GL_TEXTURE_2D);

 }

 void displayFcn (void)

 {

     glClear(GL_COLOR_BUFFER_BIT);

 //    lineTextureMapping();

     surfaceTextureMapping();

     xyCoords();

     glFlush();

 }

 void winReshapeFcn (GLint newWidth, GLint newHeight)

 {

     glViewport(, , newWidth, newHeight);

 }

 int main(int argc, char * argv[])

 {

     glutInit(&argc, argv);

     glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);

     glutInitWindowSize(winWidht, winHeight);

     glutInitWindowPosition(, );

     glutCreateWindow("texture mapping");

     init();

     glutDisplayFunc(displayFcn);

     glutReshapeFunc(winReshapeFcn);

     glutMainLoop();

     return ;

 }