问题描述
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我正在使用opengl和纹理贴图。
问题在于,当应用的纹理为512×32像素时,所有事物都可以正常工作,但是当其为128×128时,纹理无法正确应用。
纹理没有正确地重复,它被应用于对象的开始,其余部分则没有任何纹理。
在代码中:length参数约为100。
LoadTexture:读取.bmp文件并返回纹理索引的函数。
这是我正在使用的代码。
int LoadTexture(char *filename,int alpha)
{
using namespace std;
int i,j=0; //Index variables
static int num_texture;
ifstream l_file(filename);
unsigned char *l_texture; //The pointer to the memory zone in which we will load the texture
// windows.h gives us these types to work with the Bitmap files
BITMAPFILEHEADER fileheader;
BITMAPINFOHEADER infoheader;
RGBTRIPLE rgb;
num_texture++; // The counter of the current texture is increased
if(!l_file) return (-1); // Open the file for reading
l_file.read(reinterpret_cast<char *>(&fileheader),sizeof(fileheader)); // Read the fileheader
//fseek(l_file,sizeof(fileheader),SEEK_SET); // Jump the fileheader
l_file.read(reinterpret_cast<char *>(&infoheader),sizeof(infoheader)); // and read the infoheader
// Now we need to allocate the memory for our image (width * height * color deep)
l_texture = new byte [infoheader.biWidth * infoheader.biHeight * 4];
// And fill it with zeros
memset(l_texture,infoheader.biWidth * infoheader.biHeight * 4);
// At this point we can read every pixel of the image
for (i=0; i < infoheader.biWidth*infoheader.biHeight; i++)
{
// We load an RGB value from the file
l_file.read(reinterpret_cast<char *>(&rgb),sizeof(rgb));
// And store it
l_texture[j+0] = rgb.rgbtRed; // Red component
l_texture[j+1] = rgb.rgbtGreen; // Green component
l_texture[j+2] = rgb.rgbtBlue; // Blue component
l_texture[j+3] = alpha; // Alpha value
j += 4; // Go to the next position
}
l_file.close(); // Closes the file stream
glBindTexture(GL_TEXTURE_2D,num_texture); // Bind the ID texture specified by the 2nd parameter
// The next commands sets the texture parameters
glTexParameterf(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S,GL_REPEAT); // If the u,v coordinates overflow the range 0,1 the image is repeated
glTexParameterf(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T,GL_REPEAT);
glTexParameterf(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR); // The magnification function (\"linear\" produces better results)
glTexParameterf(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR_MIPMAP_LINEAR); //The minifying function
// Finally we define the 2d texture
glTexImage2D(GL_TEXTURE_2D,4,infoheader.biWidth,infoheader.biHeight,GL_RGBA,GL_UNSIGNED_BYTE,l_texture);
// And create 2d mipmaps for the minifying function
gluBuild2DMipmaps(GL_TEXTURE_2D,l_texture);
delete [] l_texture; // Free the memory we used to load the texture
return num_texture; // Returns the current texture OpenGL ID
}
这就是我在做地图坐标的方法
void drawStreetStraight(Vector2d & point1,Vector2d & point2,Vector2d & point3,Vector2d & point4,double length)
{
glEnable(GL_TEXTURE_2D);
glTexEnvf(GL_TEXTURE_ENV,GL_TEXTURE_ENV_MODE,GL_DECR);
glBindTexture(GL_TEXTURE_2D,streetTexture);
glBegin(GL_QUADS);
glTexCoord2f(0,0);
glVertex3d(point1.x,point1.y);
glTexCoord2f(1,0);
glVertex3d(point2.x,point2.y);
glTexCoord2f(1,length/2.0);
glVertex3d(point3.x,point3.y);
glTexCoord2f(0,length/2.0);
glVertex3d(point4.x,point4.y);
glEnd();
gldisable(GL_TEXTURE_2D);
}
解决方法
我不确定这是否是您的示例的修复程序,但似乎您没有在任何地方使用glGenTextures。
是否有一个原因?
我准备这样的纹理:
glGenTextures( 1,&texPlane);
glBindTexture( GL_TEXTURE_2D,texPlane );
glPixelStorei(GL_UNPACK_ALIGNMENT,1);
glTexEnvf( GL_TEXTURE_ENV,GL_TEXTURE_ENV_MODE,GL_MODULATE );
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR_MIPMAP_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S,GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T,GL_GENERATE_MIPMAP,GL_TRUE);
glTexImage2D( GL_TEXTURE_2D,GL_RGBA,512,GL_UNSIGNED_BYTE,texPlanes);