public void calculate(){
        sheet = new OpenGLTexture[sheet_width][sheet_height];

        float sprite_width = 1/(float)sheet_width;
        float sprite_height = 1/(float)sheet_height;

       for(int x = 0; x < sheet_width; x++){
            for(int y = 0; y < sheet_height; y++){

                float xPos = x*sprite_width;
                float yPos = y*sprite_height;

                sheet[x][y] = new OpenGLTexture(
                        this.source.getID(),
                        xPos, yPos,
                        xPos + sprite_width, yPos,
                        xPos + sprite_width, yPos + sprite_height,
                        xPos, yPos + sprite_height
                );

            }
        }
    }