Sprites

  
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity();						
...
//we translate and rotate the world

glTranslatef(0.0f,0.0f,z);
//we rotate the x axis, y axis and z axis

glRotatef(rx,1.0f,0.0f,0.0f);
glRotatef(ry,0.0f,1.0f,0.0f);
glRotatef(rz,0.0f,0.0f,1.0f);
//we scale

glScalef(scale,scale,scale);
...

//we draw the terrain... to bind the texture

glBindTexture(GL_TEXTURE_2D,txt.get_Texture_Coord(terrain[i][j].texture,coord));
...

//we draw the water

glDepthMask(GL_FALSE);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA,GL_ONE);
glBindTexture(GL_TEXTURE_2D,txt.get_Texture_Coord(WATER,coord));
glColor4f(0.5f,0.5f,1.0f,0.7f);	
...
glDisable(GL_BLEND);
glDepthMask(GL_TRUE);
glColor3f(1.0f,1.0f,1.0f);	

//we draw the trees (THIS IS THE PROBLEM THE SPRITE OF MY TREE

//DOESN'T WORK WELL, THE BLACK PART IS DRAWN INSTEAD OF BEING

//TRANSPARENT

glDepthMask(GL_FALSE);
glEnable(GL_ALPHA_TEST);
glAlphaFunc(GL_GREATER,0.9);
//to bind the texture

glBindTexture(GL_TEXTURE_2D,txt.get_Texture(5));
...
glDepthMask(GL_TRUE);
glDisable(GL_ALPHA_TEST);
  

  
unsigned char* LoadBitmapFile(char *f, BITMAPINFOHEADER *bih)
{
	FILE *filePtr;
	BITMAPFILEHEADER bitmapFileHeader;
	unsigned char *bitmapImage;
	int imageIdx = 0;
	unsigned char tempRGB;

	//open filename

	filePtr = fopen(f,"rb");
	if(filePtr == NULL)
		write_err("Error opening bitmap file ",f,".");

	//read header

	fread(&bitmapFileHeader, sizeof(BITMAPFILEHEADER),1,filePtr);

	//check if bitmap

	if(bitmapFileHeader.bfType != 0X4d42)
		{
		fclose(filePtr);
		}

	//read info header

	fread(bih,sizeof(BITMAPINFOHEADER),1,filePtr);

	//move file pointer to beginning

	fseek(filePtr,bitmapFileHeader.bfOffBits,SEEK_SET);

	//alocate enough mem

	bitmapImage = (unsigned char*) malloc(bih->biSizeImage);

	if(!bitmapImage)
	{
		fclose(filePtr);
	}
	
	//read bitmap

	fread(bitmapImage,1,bih->biSizeImage,filePtr);

	if(bitmapImage==NULL)
	{
		fclose(filePtr);
	}

	//swap R and B values

	for(imageIdx=0; imageIdx < (int) bih->biSizeImage;imageIdx+=3)
	{
		tempRGB = bitmapImage[imageIdx];
		bitmapImage[imageIdx] = bitmapImage[imageIdx + 2];
		bitmapImage[imageIdx+2] = tempRGB;
	}

	fclose(filePtr);
	return bitmapImage;
}

unsigned char *Texture::LoadBitmapFileWithAlpha(char *filename, BITMAPINFOHEADER *bitmapInfoHeader)
{
  unsigned char *bitmapImage = LoadBitmapFile(filename, bitmapInfoHeader);
  unsigned char *bitmapWithAlpha = (unsigned char *)malloc(bitmapInfoHeader->biSizeImage * 4 / 3);

  if (bitmapImage == NULL || bitmapWithAlpha == NULL)
    return NULL;

  // loop through the bitmap data

  for (unsigned int src = 0, dst = 0; src < bitmapInfoHeader->biSizeImage; src +=3, dst +=4)
  {
	  
    // if the pixel is black, set the alpha to 0. Otherwise, set it to 255.

    if (bitmapImage[src] == 0 && bitmapImage[src+1] == 0 && bitmapImage[src+2] == 0)
      bitmapWithAlpha[dst+3] = 0;
       else
      bitmapWithAlpha[dst+3] = 0xFF;

    // copy pixel data over

    bitmapWithAlpha[dst] = bitmapImage[src];
    bitmapWithAlpha[dst+1] = bitmapImage[src+1];
    bitmapWithAlpha[dst+2] = bitmapImage[src+2];
  }

  free(bitmapImage);

  return bitmapWithAlpha;
}