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#include <assert.h>
#include <stdio.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <GL/glew.h>
#include <GL/glu.h>
#include "readtex.h"
#include "skybox.h"
static int
load(GLenum target, const char *filename,
GLboolean flipTB, GLboolean flipLR)
{
GLint w, h;
GLenum format;
GLubyte *img = LoadRGBImage( filename, &w, &h, &format );
if (!img) {
printf("Error: couldn't load texture image %s\n", filename);
return 0;
}
assert(format == GL_RGB);
printf("Load cube face 0x%x: %s %d x %d\n", target, filename, w, h);
/* <sigh> the way the texture cube mapping works, we have to flip
* images to make things look right.
*/
if (flipTB) {
const int stride = 3 * w;
GLubyte temp[3*1024];
int i;
for (i = 0; i < h / 2; i++) {
memcpy(temp, img + i * stride, stride);
memcpy(img + i * stride, img + (h - i - 1) * stride, stride);
memcpy(img + (h - i - 1) * stride, temp, stride);
}
}
if (flipLR) {
const int stride = 3 * w;
GLubyte temp[3];
GLubyte *row;
int i, j;
for (i = 0; i < h; i++) {
row = img + i * stride;
for (j = 0; j < w / 2; j++) {
int k = w - j - 1;
temp[0] = row[j*3+0];
temp[1] = row[j*3+1];
temp[2] = row[j*3+2];
row[j*3+0] = row[k*3+0];
row[j*3+1] = row[k*3+1];
row[j*3+2] = row[k*3+2];
row[k*3+0] = temp[0];
row[k*3+1] = temp[1];
row[k*3+2] = temp[2];
}
}
}
gluBuild2DMipmaps(target, GL_RGB, w, h, format, GL_UNSIGNED_BYTE, img);
free(img);
return 1;
}
GLuint
LoadSkyBoxCubeTexture(const char *filePosX,
const char *fileNegX,
const char *filePosY,
const char *fileNegY,
const char *filePosZ,
const char *fileNegZ)
{
GLuint tex;
glGenTextures(1, &tex);
glBindTexture(GL_TEXTURE_CUBE_MAP, tex);
glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER,
GL_LINEAR_MIPMAP_NEAREST);
if (!load(GL_TEXTURE_CUBE_MAP_POSITIVE_X, filePosX, GL_TRUE, GL_TRUE))
return 0;
if (!load(GL_TEXTURE_CUBE_MAP_NEGATIVE_X, fileNegX, GL_TRUE, GL_TRUE))
return 0;
if (!load(GL_TEXTURE_CUBE_MAP_POSITIVE_Y, filePosY, GL_TRUE, GL_TRUE))
return 0;
if (!load(GL_TEXTURE_CUBE_MAP_NEGATIVE_Y, fileNegY, GL_TRUE, GL_TRUE))
return 0;
if (!load(GL_TEXTURE_CUBE_MAP_POSITIVE_Z, filePosZ, GL_TRUE, GL_TRUE))
return 0;
if (!load(GL_TEXTURE_CUBE_MAP_NEGATIVE_Z, fileNegZ, GL_TRUE, GL_TRUE))
return 0;
return tex;
}
#define eps1 0.99
#define br 20.0 /* box radius */
void
DrawSkyBoxCubeTexture(GLuint tex)
{
struct vertex {
float x, y, z, s, t, r;
};
static const struct vertex verts[24] = {
/* +X side */
{ br, -br, -br, 1.0, -eps1, -eps1 },
{ br, -br, br, 1.0, -eps1, eps1 },
{ br, br, br, 1.0, eps1, eps1 },
{ br, br, -br, 1.0, eps1, -eps1 },
/* -X side */
{ -br, br, -br, -1.0, eps1, -eps1 },
{ -br, br, br, -1.0, eps1, eps1 },
{ -br, -br, br, -1.0, -eps1, eps1 },
{ -br, -br, -br, -1.0, -eps1, -eps1 },
/* +Y side */
{ br, br, -br, eps1, 1.0, -eps1 },
{ br, br, br, eps1, 1.0, eps1 },
{ -br, br, br, -eps1, 1.0, eps1 },
{ -br, br, -br, -eps1, 1.0, -eps1 },
/* -Y side */
{ -br, -br, -br, -eps1, -1.0, -eps1 },
{ -br, -br, br, -eps1, -1.0, eps1 },
{ br, -br, br, eps1, -1.0, eps1 },
{ br, -br, -br, eps1, -1.0, -eps1 },
/* +Z side */
{ br, -br, br, eps1, -eps1, 1.0 },
{ -br, -br, br, -eps1, -eps1, 1.0 },
{ -br, br, br, -eps1, eps1, 1.0 },
{ br, br, br, eps1, eps1, 1.0 },
/* -Z side */
{ br, br, -br, eps1, eps1, -1.0 },
{ -br, br, -br, -eps1, eps1, -1.0 },
{ -br, -br, -br, -eps1, -eps1, -1.0 },
{ br, -br, -br, eps1, -eps1, -1.0 },
};
static GLuint vbo = 0;
if (!vbo ) {
glGenBuffersARB(1, &vbo);
glBindBufferARB(GL_ARRAY_BUFFER_ARB, vbo);
glBufferDataARB(GL_ARRAY_BUFFER_ARB, sizeof(verts), verts,
GL_STATIC_DRAW_ARB);
}
else {
glBindBufferARB(GL_ARRAY_BUFFER_ARB, vbo);
}
glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
glVertexPointer(3, GL_FLOAT, sizeof(struct vertex),
(void *) offsetof(struct vertex, x));
glTexCoordPointer(3, GL_FLOAT, sizeof(struct vertex),
(void *) offsetof(struct vertex, s));
glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_TEXTURE_COORD_ARRAY);
glBindTexture(GL_TEXTURE_CUBE_MAP, tex);
glEnable(GL_TEXTURE_CUBE_MAP);
glDisable(GL_BLEND);
glDrawArrays(GL_QUADS, 0, 24);
glDisable(GL_TEXTURE_CUBE_MAP);
glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_TEXTURE_COORD_ARRAY);
glBindBufferARB(GL_ARRAY_BUFFER_ARB, 0);
}
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