tuto_draw_cubemap.cpp File Reference

chargement et affichage d'une cubemap / envmap. More...

#include <memory>
#include "wavefront.h"
#include "texture.h"
#include "orbiter.h"
#include "program.h"
#include "uniforms.h"
#include "draw.h"
#include "app_camera.h"

Go to the source code of this file.

Classes
class	TP

Functions
GLuint	read_cubemap (const int unit, const char *filename, const GLenum texel_type=GL_RGBA)
	charge une image, decoupe les 6 faces et renvoie une texture cubemap. More...
int	main (int argc, char **argv)

Detailed Description

chargement et affichage d'une cubemap / envmap.

Definition in file tuto_draw_cubemap.cpp.

Function Documentation

read_cubemap()

GLuint read_cubemap	(	const int	unit,
		const char *	filename,
		const GLenum	texel_type = GL_RGBA
	)

charge une image, decoupe les 6 faces et renvoie une texture cubemap.

Definition at line 17 of file tuto_draw_cubemap.cpp.

{
    // les 6 faces sur une croix
    ImageData image= read_image_data(filename);
    if(image.pixels.empty()) 
        return 0;
    
    int w= image.width / 4;
    int h= image.height / 3;
    assert(w == h);
    
    GLenum data_format;
    GLenum data_type= GL_UNSIGNED_BYTE;
    if(image.channels == 3)
        data_format= GL_RGB;
    else // par defaut
        data_format= GL_RGBA;
    
    // creer la texture
    GLuint texture= 0;
    glGenTextures(1, &texture);
    glActiveTexture(GL_TEXTURE0 + unit);
    glBindTexture(GL_TEXTURE_CUBE_MAP, texture);
 
    // creer les 6 faces
    // chaque face de la cubemap est un rectangle [image.width/4 x image.height/3] dans l'image originale 
    struct { int x, y; } faces[]= {
        {0, 1}, // X+
        {2, 1}, // X-
        {1, 2}, // Y+
        {1, 0}, // Y- 
        {1, 1}, // Z+
        {3, 1}, // Z-
    };
    
    for(int i= 0; i < 6; i++)
    {
        ImageData face= flipX(flipY(copy(image, faces[i].x*w, faces[i].y*h, w, h)));
        
        glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X +i, 0,
            texel_type, w, h, 0,
            data_format, data_type, face.data());
    }
    
    // parametres de filtrage
    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);    
    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);    
    
    glGenerateMipmap(GL_TEXTURE_CUBE_MAP);
    
    // filtrage "correct" sur les bords du cube...
    glEnable(GL_TEXTURE_CUBE_MAP_SEAMLESS);
    //~ glDisable(GL_TEXTURE_CUBE_MAP_SEAMLESS);
    
    return texture;
}