我的问题 - >如何使颜色255,200,255在OpenGL中透明? (由透明我的意思是除去像素颜色255200255或任何作品...)OpenGL设置纹理的透明颜色
我的纹理加载函数从该教程 - >http://nehe.gamedev.net/data/lessons/lesson.asp?lesson=33
注意,我没有使用Alpha通道,我有用定制颜色(255200255),其必须是透明的/移除的像素的一组预先制作的图像..
我的节目的一些的.tga加载函数:
Texture AllTextures[1000];
typedef struct
{
GLubyte * imageData; // Image Data (Up To 32 Bits)
GLuint bpp; // Image Color Depth In Bits Per Pixel
GLuint width; // Image Width
GLuint height; // Image Height
GLuint texID; // Texture ID Used To Select A Texture
GLuint type; // Image Type (GL_RGB, GL_RGBA)
} Texture;
bool LoadUncompressedTGA(Texture * texture, char * filename, FILE * fTGA) // Load an uncompressed TGA (note, much of this code is based on NeHe's
{ // TGA Loading code nehe.gamedev.net)
if(fread(tga.header, sizeof(tga.header), 1, fTGA) == 0) // Read TGA header
{
MessageBox(NULL, "Could not read info header", "ERROR", MB_OK); // Display error
if(fTGA != NULL) // if file is still open
{
fclose(fTGA); // Close it
}
return false; // Return failular
}
texture->width = tga.header[1] * 256 + tga.header[0]; // Determine The TGA Width (highbyte*256+lowbyte)
texture->height = tga.header[3] * 256 + tga.header[2]; // Determine The TGA Height (highbyte*256+lowbyte)
texture->bpp = tga.header[4]; // Determine the bits per pixel
tga.Width = texture->width; // Copy width into local structure
tga.Height = texture->height; // Copy height into local structure
tga.Bpp = texture->bpp; // Copy BPP into local structure
if((texture->width <= 0) || (texture->height <= 0) || ((texture->bpp != 24) && (texture->bpp !=32))) // Make sure all information is valid
{
MessageBox(NULL, "Invalid texture information", "ERROR", MB_OK); // Display Error
if(fTGA != NULL) // Check if file is still open
{
fclose(fTGA); // If so, close it
}
return false; // Return failed
}
if(texture->bpp == 24) //If the BPP of the image is 24...
{
texture->type = GL_RGBA; // Set Image type to GL_RGB
}
else // Else if its 32 BPP
{
texture->type = GL_RGBA; // Set image type to GL_RGBA
}
tga.bytesPerPixel = (tga.Bpp/8); // Compute the number of BYTES per pixel
tga.imageSize = (tga.bytesPerPixel * tga.Width * tga.Height); // Compute the total amout ofmemory needed to store data
texture->imageData = (GLubyte *)malloc(tga.imageSize); // Allocate that much memory
if(texture->imageData == NULL) // If no space was allocated
{
MessageBox(NULL, "Could not allocate memory for image", "ERROR", MB_OK); // Display Error
fclose(fTGA); // Close the file
return false; // Return failed
}
if(fread(texture->imageData, 1, tga.imageSize, fTGA) != tga.imageSize) // Attempt to read image data
{
MessageBox(NULL, "Could not read image data", "ERROR", MB_OK); // Display Error
if(texture->imageData != NULL) // If imagedata has data in it
{
free(texture->imageData); // Delete data from memory
}
fclose(fTGA); // Close file
return false; // Return failed
}
// Byte Swapping Optimized By Steve Thomas
for(GLuint cswap = 0; cswap < (int)tga.imageSize; cswap += tga.bytesPerPixel)
{
texture->imageData[cswap] ^= texture->imageData[cswap+2] ^=texture->imageData[cswap] ^= texture->imageData[cswap+2];
}
fclose(fTGA); // Close file
return true; // Return success
}
void LoadMyTextureTGA(int id,char* texturename)
{
//texturename ex: "Data/Uncompressed.tga"
if(LoadTGA(&AllTextures[id], texturename))
{
//success
glGenTextures(1, &AllTextures[id].texID); // Create The Texture (CHANGE)
glBindTexture(GL_TEXTURE_2D, AllTextures[id].texID);
glTexImage2D(GL_TEXTURE_2D, 0, 3, AllTextures[id].width, AllTextures[id].height, 0, GL_RGB, GL_UNSIGNED_BYTE, AllTextures[id].imageData);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
if (AllTextures[id].imageData) // If Texture Image Exists (CHANGE)
{
free(AllTextures[id].imageData); // Free The Texture Image Memory (CHANGE)
}
}
else
{
MessageBoxA(0,"Textures Loading Fail! Game will close now","Game Problem",0);
exit(1);
}
}
,我该怎么做..?以及如何启用alpha透明度? – Tenev 2010-08-03 15:33:43
在glTexImage2D()中用GL_RGBA替换GL_RGB。这样,即使它没有在PNG中指定,你也将始终拥有一个Alpha通道。但是现在openGL会期望x * h * 4 texels,所以要分配另一个缓冲区,就像(GLubyte *)malloc(tga.imageSize);但带有x * h * 4个字节。然后对于每个纹理元素,将R,G和B组件从texture-> imageData复制到新缓冲区。如果这些RGB与您想要的值相匹配,请将A设置为255. – Calvin1602 2010-08-03 15:58:13
只需非常清楚:如果texture-> imageData是RGBARGBARGBARGBA ....(即texture-> bpp == 32),请不要更改您的代码;如果texture-> imageData是RGBRGBRGBRGB ....(即texture-> bpp == 24),则必须将其转换为RGBARGBARGBARGBA,然后自己计算A – Calvin1602 2010-08-03 16:00:20