opengl 纹理映射

最新推荐文章于 2022-02-23 15:02:25 发布

原创最新推荐文章于 2022-02-23 15:02:25 发布 · 829 阅读

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CC 4.0 BY-SA版权

文章标签：

#alignment #filter #buffer #include #byte #c

本文介绍了一个使用OpenGL进行纹理映射的示例程序。该程序通过创建一个简单的棋盘格图像并将其作为纹理应用于3D几何体上，展示了如何初始化OpenGL环境、生成纹理对象、加载纹理数据以及设置纹理参数等关键步骤。

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

#define checkImageWidth 64
#define checkImageHight 64

static GLubyte checkImage[checkImageWidth][checkImageHight][4];
static GLuint texName;

void makeCheckImages()
{
int i,j,c;
for (i=0; i<checkImageHight; i++)
{
   for (j=0; j<checkImageWidth; j++)
   {
    c = ((((i&0x8) == 0)^((j&0x8)) == 0)) * 255;
    if (c == 255)
    {
     checkImage[i][j][0] = (GLubyte) 180;
     checkImage[i][j][1] = (GLubyte) 180;
     checkImage[i][j][2] = (GLubyte) 180;
     checkImage[i][j][3] = (GLubyte) 255;
    }
    else
    {
     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()
{
glClearColor(1.0, 1.0, 1.0, 0.0);
glShadeModel(GL_FLAT);
glEnable(GL_DEPTH_TEST);

makeCheckImages();
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glGenTextures(1, &texName);
glBindTexture(GL_TEXTURE_2D, texName);

glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, checkImageWidth, checkImageHight, 0, GL_RGBA, GL_UNSIGNED_BYTE, checkImage);

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
}

void display()
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);

glEnable(GL_TEXTURE_2D);

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

int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
glutInitWindowPosition(100, 100);
glutInitWindowSize(500,500);
glutCreateWindow("wen li ying she");

init();

glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutMainLoop();

return 0;
}