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#include "image_loader.h"
#include <cmath>
#include "wx/image.h"
#include "wx/wx.h"
GLuint* loadImage(wxString path, int* imageWidth, int* imageHeight, int* textureWidth, int* textureHeight)
{
GLuint* ID=new GLuint[1];
glGenTextures( 1, &ID[0] );
glBindTexture( GL_TEXTURE_2D, *ID );
// the first time, init image handlers (remove this part if you do it somewhere else in your app)
static bool is_first_time = true;
if(is_first_time)
{
wxInitAllImageHandlers();
is_first_time = false;
}
// check the file exists
if(!wxFileExists(path))
{
wxMessageBox( _("Failed to load resource image") );
exit(1);
}
wxImage* img=new wxImage( path );
(*imageWidth)=img->GetWidth();
(*imageHeight)=img->GetHeight();
glPixelStorei(GL_UNPACK_ALIGNMENT, 1 );
/*
* Many graphics card require that textures be power of two.
* Below is a simple implementation, probably not optimal but working.
* If your texture sizes are not restricted to power of 2s, you can
* of course adapt the bit below as needed.
*/
float power_of_two_that_gives_correct_width=std::log((float)(*imageWidth))/std::log(2.0);
float power_of_two_that_gives_correct_height=std::log((float)(*imageHeight))/std::log(2.0);
// check if image dimensions are a power of two
if( (int)power_of_two_that_gives_correct_width == power_of_two_that_gives_correct_width &&
(int)power_of_two_that_gives_correct_height == power_of_two_that_gives_correct_height)
{
// note: must make a local copy before passing the data to OpenGL, as GetData() returns RGB
// and we want the Alpha channel if it's present. Additionally OpenGL seems to interpret the
// data upside-down so we need to compensate for that.
GLubyte *bitmapData=img->GetData();
GLubyte *alphaData=img->GetAlpha();
int bytesPerPixel = img->HasAlpha() ? 4 : 3;
int imageSize = (*imageWidth) * (*imageHeight) * bytesPerPixel;
GLubyte *imageData=new GLubyte[imageSize];
int rev_val=(*imageHeight)-1;
for(int y=0; y<(*imageHeight); y++)
{
for(int x=0; x<(*imageWidth); x++)
{
imageData[(x+y*(*imageWidth))*bytesPerPixel+0]=
bitmapData[( x+(rev_val-y)*(*imageWidth))*3];
imageData[(x+y*(*imageWidth))*bytesPerPixel+1]=
bitmapData[( x+(rev_val-y)*(*imageWidth))*3 + 1];
imageData[(x+y*(*imageWidth))*bytesPerPixel+2]=
bitmapData[( x+(rev_val-y)*(*imageWidth))*3 + 2];
if(bytesPerPixel==4) imageData[(x+y*(*imageWidth))*bytesPerPixel+3]=
alphaData[ x+(rev_val-y)*(*imageWidth) ];
}//next
}//next
// if yes, everything is fine
glTexImage2D(GL_TEXTURE_2D,
0,
bytesPerPixel,
*imageWidth,
*imageHeight,
0,
img->HasAlpha() ? GL_RGBA : GL_RGB,
GL_UNSIGNED_BYTE,
imageData);
(*textureWidth) = (*imageWidth);
(*textureHeight) = (*imageHeight);
delete [] imageData;
}
else // texture is not a power of two. We need to resize it
{
int newWidth=(int)std::pow( 2.0, (int)(std::ceil(power_of_two_that_gives_correct_width)) );
int newHeight=(int)std::pow( 2.0, (int)(std::ceil(power_of_two_that_gives_correct_height)) );
//printf("Unsupported image size. Recommand values: %i %i\n",newWidth,newHeight);
GLubyte *bitmapData=img->GetData();
GLubyte *alphaData=img->GetAlpha();
int old_bytesPerPixel = 3;
int bytesPerPixel = img->HasAlpha() ? 4 : 3;
int imageSize = newWidth * newHeight * bytesPerPixel;
GLubyte *imageData=new GLubyte[imageSize];
int rev_val=(*imageHeight)-1;
for(int y=0; y<newHeight; y++)
{
for(int x=0; x<newWidth; x++)
{
if( x<(*imageWidth) && y<(*imageHeight) ){
imageData[(x+y*newWidth)*bytesPerPixel+0]=
bitmapData[( x+(rev_val-y)*(*imageWidth))*old_bytesPerPixel + 0];
imageData[(x+y*newWidth)*bytesPerPixel+1]=
bitmapData[( x+(rev_val-y)*(*imageWidth))*old_bytesPerPixel + 1];
imageData[(x+y*newWidth)*bytesPerPixel+2]=
bitmapData[( x+(rev_val-y)*(*imageWidth))*old_bytesPerPixel + 2];
if(bytesPerPixel==4) imageData[(x+y*newWidth)*bytesPerPixel+3]=
alphaData[ x+(rev_val-y)*(*imageWidth) ];
}
else
{
imageData[(x+y*newWidth)*bytesPerPixel+0] = 0;
imageData[(x+y*newWidth)*bytesPerPixel+1] = 0;
imageData[(x+y*newWidth)*bytesPerPixel+2] = 0;
if(bytesPerPixel==4) imageData[(x+y*newWidth)*bytesPerPixel+3] = 0;
}
}//next
}//next
glTexImage2D(GL_TEXTURE_2D,
0,
img->HasAlpha() ? 4 : 3,
newWidth,
newHeight,
0,
img->HasAlpha() ? GL_RGBA : GL_RGB,
GL_UNSIGNED_BYTE,
imageData);
(*textureWidth)=newWidth;
(*textureHeight)=newHeight;
delete [] imageData;
}
// set texture parameters as you wish
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); // GL_LINEAR
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); // GL_LINEAR
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
return ID;
}
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