c - GL_REPEAT 和 GL_CLAMP 给出相同的结果

Question

在 OpenGL 中生成纹理时，我遇到了 GL_REPEAT 和 GL_CLAMP 问题。在我的以下代码中，我使用 GL_REPEAT 和 GL_CLAMP 得到相同的结果(它总是重复)......我没有看到我的代码与许多教程中的代码有任何区别。请帮我找出这个错误。我尝试将图像大小从 4 增加到 128 ..但 GL_CLAMP 和 GL_REPEAT 之间仍然没有区别

#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glut.h>

#include <cmath>
#include <stdlib.h>
#include <stdio.h>

/*  Create checkerboard texture  */
#define checkImageWidth 64
#define checkImageHeight 64
static float checkImage[checkImageHeight][checkImageWidth][4];

static GLuint texName;

void makeCheckImage(void)
{
   int i, j;
   float c;

   for (i = 0; i < checkImageHeight; i++) {
      for (j = 0; j < checkImageWidth; j++) {
//         c = ((((i&0x8)==0)^((j&0x8))==0))*255;
            c = 10*sin(i*j);
//         checkImage[i][j][0] = (GLubyte) c*0;
         checkImage[i][j][0] =  c*0.1;
         checkImage[i][j][1] =  c*0.25;
         checkImage[i][j][2] =  c*0.0;
         checkImage[i][j][3] = 250;
      }
   }
}

void init(void)
{    
   glClearColor (0.0, 0.0, 0.0, 0.0);
   glShadeModel(GL_FLAT);
   glEnable(GL_DEPTH_TEST);

   makeCheckImage();
   glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

   glGenTextures(1, &texName);
   glBindTexture(GL_TEXTURE_2D, texName);

   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, 
                   GL_LINEAR);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, 
                   GL_NEAREST);
   glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, checkImageWidth, 
                checkImageHeight, 0, GL_RGBA, GL_FLOAT, 
                checkImage);
}

void display(void)
{
   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
   gluLookAt(1, -1, 1, 0, 1, 0, 0, 0, 1);
   glEnable(GL_TEXTURE_2D);
   glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);
   glBindTexture(GL_TEXTURE_2D, texName);
   glMatrixMode(GL_MODELVIEW);
    //glLoadIdentity();

  // glLoadIdentity();
    glPushMatrix();

   glBegin(GL_QUADS);
   glTexCoord2f(0.0, 0.0); glVertex3f(-2.0, -1.0, 0.0);
   glTexCoord2f(0.0, 1.0); glVertex3f(-2.0, 1.0, 0.0);
   glTexCoord2f(1.0, 1.0); glVertex3f(0.0, 1.0, 0.0);
   glTexCoord2f(1.0, 0.0); glVertex3f(0.0, -1.0, 0.0);

   glTexCoord2f(0.0, 0.0); glVertex3f(1.0, -1.0, 0.0);
   glTexCoord2f(0.0, 1.0); glVertex3f(1.0, 1.0, 0.0);
   glTexCoord2f(1.0, 1.0); glVertex3f(2.41421, 1.0, -1.41421);
   glTexCoord2f(1.0, 0.0); glVertex3f(2.41421, -2.0, -1.41421);

    glPopMatrix();


   glPushMatrix();
   /*
    glTranslated(-6, -2, 1);
    glScaled(0.5,0.5,0.5) ;
   //GLint mysphereID;
   GLUquadricObj *sphere=NULL;
  sphere = gluNewQuadric();
  gluQuadricDrawStyle(sphere, GLU_LINE);
  gluQuadricTexture(sphere, GL_TRUE);
  gluQuadricNormals(sphere, GLU_SMOOTH);
  gluSphere(sphere, 01.0, 100, 100);
*/
  glPopMatrix();

   glPushMatrix();

    glColor3f(0.7f, 0.0f, 0.4f);
    glTranslated(-1, -3, -1);
     glScaled(0.5,0.5,0.5) ;
    GLUquadricObj *quadObj = gluNewQuadric();
     gluQuadricDrawStyle(quadObj, GLU_LINE);
      gluQuadricNormals(quadObj, GLU_SMOOTH);
      gluQuadricTexture(quadObj, GL_TRUE);
    gluCylinder(quadObj, 0.8, 0.8, 1.4, 100, 100);

    glPopMatrix();

   glDisable(GL_TEXTURE_2D);
  //gluDeleteQuadric(sphere);
  gluDeleteQuadric(quadObj);


   glEnd();
   glFlush();

}

void reshape(int w, int h)
{
   glViewport(0, 0, (GLsizei) w, (GLsizei) h);
   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
   gluPerspective(100.0, (GLfloat) w/(GLfloat) h, 1.0, 30.0);
   glMatrixMode(GL_MODELVIEW);
   glLoadIdentity();
   glTranslatef(0.0, 0.0, -3.6);
}

void keyboard (unsigned char key, int x, int y)
{
   switch (key) {
      case 27:
         exit(0);
         break;
      default:
         break;
   }
}

int main(int argc, char** argv)
{
   glutInit(&argc, argv);
   //glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
   glutInitWindowSize(550, 550);
   glutInitWindowPosition(100, 100);
   glutCreateWindow(argv[0]);
   init();
   glutDisplayFunc(display);
   glutReshapeFunc(reshape);
   glutKeyboardFunc(keyboard);
   glutMainLoop();
   return 0; 
}

Answer 1

除非您的纹理坐标在 0 到 1 的范围之外，否则您不会看到差异。否则没有什么可以钳制或重复。