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/*******************************************************************
* *
* Using SDL With OpenGL *
* *
* Tutorial by Kyle Foley (sdw) *
* *
* http://gpwiki.org/index.php/SDL:Tutorials:Using_SDL_with_OpenGL *
* *
*******************************************************************/
/*
THIS WORK, INCLUDING THE SOURCE CODE, DOCUMENTATION
AND RELATED MEDIA AND DATA, IS PLACED INTO THE PUBLIC DOMAIN.
THE ORIGINAL AUTHOR IS KYLE FOLEY.
THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY
OF ANY KIND, NOT EVEN THE IMPLIED WARRANTY OF
MERCHANTABILITY. THE AUTHOR OF THIS SOFTWARE,
ASSUMES _NO_ RESPONSIBILITY FOR ANY CONSEQUENCE
RESULTING FROM THE USE, MODIFICATION, OR
REDISTRIBUTION OF THIS SOFTWARE.
*/
#include "SDL/SDL.h"
#include "SDL/SDL_image.h"
#include "SDL/SDL_opengl.h"
#include <stdio.h>
#include <string.h>
#include <assert.h>
#define MAX(x, y) ((x) > (y) ? (x) : (y))
int hasext(const char *exts, const char *ext) // from cube2, zlib licensed
{
int len = strlen(ext);
if(len) for(const char *cur = exts; (cur = strstr(cur, ext)); cur += len)
{
if((cur == exts || cur[-1] == ' ') && (cur[len] == ' ' || !cur[len])) return 1;
}
return 0;
}
int main(int argc, char *argv[])
{
SDL_Surface *screen;
// Slightly different SDL initialization
if ( SDL_Init(SDL_INIT_VIDEO) != 0 ) {
printf("Unable to initialize SDL: %s\n", SDL_GetError());
return 1;
}
SDL_GL_SetAttribute( SDL_GL_DOUBLEBUFFER, 1 ); // *new*
screen = SDL_SetVideoMode( 600, 600, 16, SDL_OPENGL ); // *changed*
if ( !screen ) {
printf("Unable to set video mode: %s\n", SDL_GetError());
return 1;
}
// Check extensions
const char *exts = (const char *)glGetString(GL_EXTENSIONS);
assert(hasext(exts, "GL_EXT_texture_filter_anisotropic"));
GLint aniso;
glGetIntegerv(GL_MAX_TEXTURE_MAX_ANISOTROPY_EXT, &aniso);
printf("Max anisotropy: %d (using that)\n", aniso);
assert(aniso >= 4);
// Set the OpenGL state after creating the context with SDL_SetVideoMode
glClearColor( 0, 0, 0, 0 );
#if !EMSCRIPTEN
glEnable( GL_TEXTURE_2D ); // Need this to display a texture XXX unnecessary in OpenGL ES 2.0/WebGL
#endif
glViewport( 0, 0, 600, 600 );
glMatrixMode( GL_PROJECTION );
GLfloat matrixData[] = { 2.0/600, 0, 0, 0,
0, -2.0/600, 0, 0,
0, 0, -2.0/600, 0,
-1, 1, 0, 1 };
glLoadMatrixf(matrixData); // test loadmatrix
glMatrixMode( GL_MODELVIEW );
glLoadIdentity();
// Load the OpenGL texture
GLuint texture, texture2;
const int DDS_SIZE = 43920;
FILE *dds = fopen("water.dds", "rb");
assert(dds);
char *ddsdata = (char*)malloc(DDS_SIZE);
assert(fread(ddsdata, 1, DDS_SIZE, dds) == DDS_SIZE);
fclose(dds);
{
glGenTextures( 1, &texture );
glBindTexture( GL_TEXTURE_2D, texture );
char *curr = ddsdata + 128;
int level = 0;
int w = 512;
int h = 64;
while (level < 5) {
printf("uploading level %d: %d, %d\n", level, w, h);
assert(!glGetError());
glCompressedTexImage2D(GL_TEXTURE_2D, level, GL_COMPRESSED_RGBA_S3TC_DXT5_EXT, w, h, 0, w*h, curr);
assert(!glGetError());
curr += MAX(w, 4)*MAX(h, 4);
w /= 2;
h /= 2;
level++;
}
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
}
{
glGenTextures( 1, &texture2 );
glBindTexture( GL_TEXTURE_2D, texture2 );
char *curr = ddsdata + 128;
int level = 0;
int w = 512;
int h = 64;
while (level < 5) {
printf("uploading level %d: %d, %d\n", level, w, h);
assert(!glGetError());
glCompressedTexImage2D(GL_TEXTURE_2D, level, GL_COMPRESSED_RGBA_S3TC_DXT5_EXT, w, h, 0, w*h, curr);
assert(!glGetError());
curr += MAX(w, 4)*MAX(h, 4);
w /= 2;
h /= 2;
level++;
}
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAX_ANISOTROPY_EXT, aniso);
}
{
assert(!glGetError());
glBindFramebuffer(GL_RENDERBUFFER, 0);
assert(glGetError());
}
// Prepare and Render
// Clear the screen before drawing
glClear( GL_COLOR_BUFFER_BIT );
// Bind the texture to which subsequent calls refer to
int w = 10;
int n = 15;
glBindTexture( GL_TEXTURE_2D, texture );
for (int x = 0; x < n; x++) {
int start = x*w*2;
glBegin( GL_TRIANGLES );
glTexCoord2i( 1, 0 ); glVertex3f( start , 0, 0 );
glTexCoord2i( 0, 0 ); glVertex3f( start+w, 300, 0 );
glTexCoord2i( 1, 1 ); glVertex3f( start-w, 300, 0 );
glEnd();
}
glBindTexture( GL_TEXTURE_2D, texture2 );
for (int x = 0; x < n; x++) {
int start = n*w*2 + x*w*2;
glBegin( GL_TRIANGLES );
glTexCoord2i( 1, 0 ); glVertex3f( start , 0, 0 );
glTexCoord2i( 0, 0 ); glVertex3f( start+w, 300, 0 );
glTexCoord2i( 1, 1 ); glVertex3f( start-w, 300, 0 );
glEnd();
}
/*
int w = 8;
int n = 20;
for (int x = 0; x < n; x++) {
for (int y = 0; y < n*2; y++) {
glBindTexture( GL_TEXTURE_2D, texture );
glBegin( GL_TRIANGLE_STRIP );
glTexCoord2i( 0, 0 ); glVertex3f( x*w, y*(w), 0 );
glTexCoord2i( 1, 0 ); glVertex3f( (x+1)*(w-2*y/n), y*(w), 0 );
glTexCoord2i( 1, 1 ); glVertex3f( (x+1)*(w-2*y/n), (y+1)*(w), 0 );
glTexCoord2i( 0, 1 ); glVertex3f( x*w, (y+1)*(w), 0 );
glEnd();
glBindTexture( GL_TEXTURE_2D, texture2 );
glBegin( GL_TRIANGLE_STRIP );
glTexCoord2i( 0, 0 ); glVertex3f( n*w + x*w, y*(w), 0 );
glTexCoord2i( 1, 0 ); glVertex3f( n*w + (x+1)*(w-2*y/n), y*(w), 0 );
glTexCoord2i( 1, 1 ); glVertex3f( n*w + (x+1)*(w-2*y/n), (y+1)*(w), 0 );
glTexCoord2i( 0, 1 ); glVertex3f( n*w + x*w, (y+1)*(w), 0 );
glEnd();
}
}
*/
SDL_GL_SwapBuffers();
#if !EMSCRIPTEN
// Wait for 3 seconds to give us a chance to see the image
SDL_Delay(2000);
#endif
// Now we can delete the OpenGL texture and close down SDL
glDeleteTextures( 1, &texture );
SDL_Quit();
return 0;
}
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