opengl入门系列1- OpenGL纹理环绕
2014-09-11 10:23
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//在Ubuntu12.04 QT 上编译通过;
先上代码:
#include <GL/glut.h>
#include <stdlib.h>
#include <stdio.h>
/* Create checkerboard texture */
#define checkImageWidth 64
#define checkImageHeight 64
static GLubyte checkImage[checkImageHeight][checkImageWidth][4];
#ifdef GL_VERSION_1_1
static GLuint texName;
#endif
void makeCheckImage(void)
{
int i, j, c;
for (i = 0; i < checkImageHeight; i++) {
for (j = 0; j < checkImageWidth; j++) {
c = ((((i&0x8)==0)^((j&0x8))==0))*255;
checkImage[i][j][0] = (GLubyte) c;
checkImage[i][j][1] = (GLubyte) c;
checkImage[i][j][2] = (GLubyte) c;
checkImage[i][j][3] = (GLubyte) 255;
}
}
}
void init(void)
{
glClearColor (0.0, 0.0, 0.0, 0.0);
glShadeModel(GL_FLAT);
glEnable(GL_DEPTH_TEST);
makeCheckImage();
//设置像素对齐模式 对glTexImage2D,glTexSubImage2D 有影响
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
#ifdef GL_VERSION_1_1
glGenTextures(1, &texName);
glBindTexture(GL_TEXTURE_2D, texName);
#endif
/*
*纹理坐标可以超出(0, 1)范围,并且在纹理映射过程中可以重复映射或约简映射。、
*在重复映射的情况下,纹理可以在s,t方向上重复
*/
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
//GL_NEAREST: 使用纹理中坐标最接近的一个像素的颜色作为需要绘制的像素颜色, 锯齿现象明显
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
#ifdef GL_VERSION_1_1
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, checkImageWidth, checkImageHeight,
0, GL_RGBA, GL_UNSIGNED_BYTE, checkImage);
#else
glTexImage2D(GL_TEXTURE_2D, 0, 4, checkImageWidth, checkImageHeight,
0, GL_RGBA, GL_UNSIGNED_BYTE, checkImage);
#endif
}
void display(void)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glEnable(GL_TEXTURE_2D);
//设置的纹理模式
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);
#ifdef GL_VERSION_1_1
glBindTexture(GL_TEXTURE_2D, texName);
#endif
glBegin(GL_QUADS);
glTexCoord2f(0.0, 0.0); glVertex3f(-2.0, -1.0, 0.0);
glTexCoord2f(0.0, 3.0); glVertex3f(-2.0, 1.0, 0.0);
glTexCoord2f(3.0, 3.0); glVertex3f(0.0, 1.0, 0.0);
glTexCoord2f(3.0, 0.0); glVertex3f(0.0, -1.0, 0.0);
glTexCoord2f(0.0, 0.0); glVertex3f(1.0, -1.0, 0.0);
glTexCoord2f(0.0, 3.0); glVertex3f(1.0, 1.0, 0.0);
glTexCoord2f(3.0, 3.0); glVertex3f(2.41421, 1.0, -1.41421);
glTexCoord2f(3.0, 0.0); glVertex3f(2.41421, -1.0, -1.41421);
glEnd();
glFlush();
glDisable(GL_TEXTURE_2D);
}
void reshape(int w, int h)
{
glViewport(0, 0, (GLsizei) w, (GLsizei) h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(60.0, (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 's':
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
glutPostRedisplay();
break;
case 'S':
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glutPostRedisplay();
break;
case 't':
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
glutPostRedisplay();
break;
case 'T':
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glutPostRedisplay();
break;
case 27:
exit(0);
break;
default:
break;
}
}
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
glutInitWindowSize(250, 250);
glutInitWindowPosition(100, 100);
glutCreateWindow(argv[0]);
init();
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutKeyboardFunc(keyboard);
glutMainLoop();
return 0;
}
//工程设置:
TEMPLATE = app
CONFIG += console
CONFIG -= qt
SOURCES += \
wrap.c
LIBS += -L/usr/lib/
LIBS += -lglut
LIBS += -lGL
LIBS += -lGLU
//效果:
//背景知识:
纹理相关函数:
先上代码:
#include <GL/glut.h>
#include <stdlib.h>
#include <stdio.h>
/* Create checkerboard texture */
#define checkImageWidth 64
#define checkImageHeight 64
static GLubyte checkImage[checkImageHeight][checkImageWidth][4];
#ifdef GL_VERSION_1_1
static GLuint texName;
#endif
void makeCheckImage(void)
{
int i, j, c;
for (i = 0; i < checkImageHeight; i++) {
for (j = 0; j < checkImageWidth; j++) {
c = ((((i&0x8)==0)^((j&0x8))==0))*255;
checkImage[i][j][0] = (GLubyte) c;
checkImage[i][j][1] = (GLubyte) c;
checkImage[i][j][2] = (GLubyte) c;
checkImage[i][j][3] = (GLubyte) 255;
}
}
}
void init(void)
{
glClearColor (0.0, 0.0, 0.0, 0.0);
glShadeModel(GL_FLAT);
glEnable(GL_DEPTH_TEST);
makeCheckImage();
//设置像素对齐模式 对glTexImage2D,glTexSubImage2D 有影响
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
#ifdef GL_VERSION_1_1
glGenTextures(1, &texName);
glBindTexture(GL_TEXTURE_2D, texName);
#endif
/*
*纹理坐标可以超出(0, 1)范围,并且在纹理映射过程中可以重复映射或约简映射。、
*在重复映射的情况下,纹理可以在s,t方向上重复
*/
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
//GL_NEAREST: 使用纹理中坐标最接近的一个像素的颜色作为需要绘制的像素颜色, 锯齿现象明显
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
#ifdef GL_VERSION_1_1
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, checkImageWidth, checkImageHeight,
0, GL_RGBA, GL_UNSIGNED_BYTE, checkImage);
#else
glTexImage2D(GL_TEXTURE_2D, 0, 4, checkImageWidth, checkImageHeight,
0, GL_RGBA, GL_UNSIGNED_BYTE, checkImage);
#endif
}
void display(void)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glEnable(GL_TEXTURE_2D);
//设置的纹理模式
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);
#ifdef GL_VERSION_1_1
glBindTexture(GL_TEXTURE_2D, texName);
#endif
glBegin(GL_QUADS);
glTexCoord2f(0.0, 0.0); glVertex3f(-2.0, -1.0, 0.0);
glTexCoord2f(0.0, 3.0); glVertex3f(-2.0, 1.0, 0.0);
glTexCoord2f(3.0, 3.0); glVertex3f(0.0, 1.0, 0.0);
glTexCoord2f(3.0, 0.0); glVertex3f(0.0, -1.0, 0.0);
glTexCoord2f(0.0, 0.0); glVertex3f(1.0, -1.0, 0.0);
glTexCoord2f(0.0, 3.0); glVertex3f(1.0, 1.0, 0.0);
glTexCoord2f(3.0, 3.0); glVertex3f(2.41421, 1.0, -1.41421);
glTexCoord2f(3.0, 0.0); glVertex3f(2.41421, -1.0, -1.41421);
glEnd();
glFlush();
glDisable(GL_TEXTURE_2D);
}
void reshape(int w, int h)
{
glViewport(0, 0, (GLsizei) w, (GLsizei) h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(60.0, (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 's':
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
glutPostRedisplay();
break;
case 'S':
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glutPostRedisplay();
break;
case 't':
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
glutPostRedisplay();
break;
case 'T':
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glutPostRedisplay();
break;
case 27:
exit(0);
break;
default:
break;
}
}
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
glutInitWindowSize(250, 250);
glutInitWindowPosition(100, 100);
glutCreateWindow(argv[0]);
init();
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutKeyboardFunc(keyboard);
glutMainLoop();
return 0;
}
//工程设置:
TEMPLATE = app
CONFIG += console
CONFIG -= qt
SOURCES += \
wrap.c
LIBS += -L/usr/lib/
LIBS += -lglut
LIBS += -lGL
LIBS += -lGLU
//效果:
//背景知识:
纹理相关函数:
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