I have a single texture working, but I cannot figure out how to switch between 2, or how glBindTexture actually works.
I copied this from somewhere and it works, and I believe that I understand most of it. Problem is, I can uncomment glBindTexture(GL_TEXTURE_2D, texture[0].texID); and it works. Which I don't understand. This code shouldn't be a problem, I think it's something simple I am missing.
bool LoadTGA(TextureImage *texture, char *filename) // Loads A TGA File Into Memory
{
GLubyte TGAheader[12]={0,0,2,0,0,0,0,0,0,0,0,0}; // Uncompressed TGA Header
GLubyte TGAcompare[12]; // Used To Compare TGA Header
GLubyte header[6]; // First 6 Useful Bytes From The Header
GLuint bytesPerPixel; // Holds Number Of Bytes Per Pixel Used In The TGA File
GLuint imageSize; // Used To Store The Image Size When Setting Aside Ram
GLuint temp; // Temporary Variable
GLuint type=GL_RGBA; // Set The Default GL Mode To RBGA (32 BPP)
system("cd");
FILE *file = fopen(filename, "r"); // Open The TGA File
if( file==NULL || // Does File Even Exist?
fread(TGAcompare,1,sizeof(TGAcompare),file)!=sizeof(TGAcompare) || // Are There 12 Bytes To Read?
memcmp(TGAheader,TGAcompare,sizeof(TGAheader))!=0 || // Does The Header Match What We Want?
fread(header,1,sizeof(header),file)!=sizeof(header)) // If So Read Next 6 Header Bytes
{
if (file == NULL) // Did The File Even Exist? *Added Jim Strong*
{
perror("Error");
return false; // Return False
}
else
{
fclose(file); // If Anything Failed, Close The File
perror("Error");
return false; // Return False
}
}
texture->width = header[1] * 256 + header[0]; // Determine The TGA Width (highbyte*256+lowbyte)
texture->height = header[3] * 256 + header[2]; // Determine The TGA Height (highbyte*256+lowbyte)
if( texture->width <=0 || // Is The Width Less Than Or Equal To Zero
texture->height <=0 || // Is The Height Less Than Or Equal To Zero
(header[4]!=24 && header[4]!=32)) // Is The TGA 24 or 32 Bit?
{
fclose(file); // If Anything Failed, Close The File
return false; // Return False
}
texture->bpp = header[4]; // Grab The TGA's Bits Per Pixel (24 or 32)
bytesPerPixel = texture->bpp/8; // Divide By 8 To Get The Bytes Per Pixel
imageSize = texture->width*texture->height*bytesPerPixel; // Calculate The Memory Required For The TGA Data
texture->imageData=(GLubyte *)malloc(imageSize); // Reserve Memory To Hold The TGA Data
if( texture->imageData==NULL || // Does The Storage Memory Exist?
fread(texture->imageData, 1, imageSize, file)!=imageSize) // Does The Image Size Match The Memory Reserved?
{
if(texture->imageData!=NULL) // Was Image Data Loaded
free(texture->imageData); // If So, Release The Image Data
fclose(file); // Close The File
return false; // Return False
}
for(GLuint i=0; i<int(imageSize); i+=bytesPerPixel) // Loop Through The Image Data
{ // Swaps The 1st And 3rd Bytes ('R'ed and 'B'lue)
temp=texture->imageData[i]; // Temporarily Store The Value At Image Data 'i'
texture->imageData[i] = texture->imageData[i + 2]; // Set The 1st Byte To The Value Of The 3rd Byte
texture->imageData[i + 2] = temp; // Set The 3rd Byte To The Value In 'temp' (1st Byte Value)
}
fclose (file); // Close The File
// Build A Texture From The Data
glGenTextures(1, &texture[0].texID); // Generate OpenGL texture IDs
//glBindTexture(GL_TEXTURE_2D, texture[0].texID); // Bind Our Texture
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); // Linear Filtered
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); // Linear Filtered
//glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
//glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
if (texture[0].bpp==24) // Was The TGA 24 Bits
{
type=GL_RGB; // If So Set The 'type' To GL_RGB
}
glTexImage2D(GL_TEXTURE_2D, 0, type, texture[0].width, texture[0].height, 0, type, GL_UNSIGNED_BYTE, texture[0].imageData);
return true;
Now when I draw I have this:
glEnable(GL_TEXTURE_2D);
//glBindTexture(GL_TEXTURE_2D, texturesList[0].texID);
glColor4f(1, 1, 1, 1);
glBegin(GL_POLYGON);
glTexCoord2f(0.0f, 0.0f);
glVertex4f(-50, 0, 50, 1);
glTexCoord2f(50.0f, 0.0f);
glVertex4f(-50, 0, -50, 1);
glTexCoord2f(50.0f, 50.0f);
glVertex4f(50, 0, -50, 1);
glTexCoord2f(0.0f, 50.0f);
glVertex4f(50, 0, 50, 1);
glEnd();
glDisable(GL_TEXTURE_2D);
And this at the start of the program:
LoadTGA(&texturesList[0], "\snow.tga");
LoadTGA(&texturesList[1], "\snow2.tga");
So after it loads them texturesList contains 2 textures with ids of 1 and 2.
So do I not call glBindTexture(GL_TEXTURE_2D, texturesList[0].texID); before I draw to choose the right texture? Because I have to tell glTexCoord2f what to operate on?
It works perfectly if I never call glBind in my draw, but if I do nothing shows up. What I am more confused about is that it glBind doesn't need to be called for it to work.
But the last texture I create gets shown(snow2.tga).
If I can clear anything up let me know.
