我正在尝试通过在正交投影矩阵上创建一个四边形并为其添加纹理来设置我的OpenGL窗口的背景图像。我还在我的应用程序中使用了GLUT工具包。
然而,我遇到了几个问题。下面是说明问题的截图:图像是灰度的,并且在x和y上重复出现,即使纹理大小被设置为与四边形相同。
这是我想要实现的效果:
这是我得到的结果:
渲染和加载纹理的代码如下:
void orthogonalStart (void) {
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
gluOrtho2D(0, w1, 0, h1);
glScalef(1, -1, 1);
glTranslatef(0, -h1, 0);
glMatrixMode(GL_MODELVIEW);
}
void orthogonalEnd (void) {
glMatrixMode(GL_PROJECTION);
glPopMatrix();
glMatrixMode(GL_MODELVIEW);
}
GLuint LoadTexture( const char * filename, int width, int height )
{
GLuint texture;
unsigned char * data;
FILE * file;
//The following code will read in our RAW file
file = fopen( filename, "rb" );
if ( file == NULL ) return 0;
data = (unsigned char *)malloc( width * height * 3 );
fread( data, width * height * 3, 1, file );
fclose( file );
glGenTextures( 1, &texture );
glBindTexture( GL_TEXTURE_2D, texture );
glTexEnvf( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );
//even better quality, but this will do for now.
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,GL_LINEAR );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER,GL_LINEAR );
//to the edge of our shape.
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT );
//Generate the texture
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0,GL_RGB, GL_UNSIGNED_BYTE, data);
free( data ); //free the texture
return texture; //return whether it was successful
}
void FreeTexture( GLuint texture )
{
glDeleteTextures( 1, &texture );
}
void background (void) {
glBindTexture( GL_TEXTURE_2D, texture );
orthogonalStart();
glBegin(GL_QUADS);
glTexCoord2d(0.0,0.0); glVertex2f(0, 0);
glTexCoord2d(1.0,0.0); glVertex2f(1024, 0);
glTexCoord2d(1.0,1.0); glVertex2f(1024, 1024);
glTexCoord2d(0.0,1.0); glVertex2f(0, 1024);
glEnd();
orthogonalEnd();
}
void display (void) {
glClearColor (1.0,0.0,0.0,1.0);
glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
glEnable( GL_TEXTURE_2D );
background();
gluLookAt (0.0, 0.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
glutSwapBuffers();
}
我使用Photoshop将纹理从PNG格式转换为Raw格式,所以我认为灰度图像可能是由于转换而来。
注意: 我刚刚开始学习openGL,所以这可能不是最好的方法。如果有更好的方法,请告诉我。
编辑:图像必须保持在一个位置并且不重新缩放。