| /******************************************************************* |
| * * |
| * 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 <stdlib.h> |
| #include <string.h> |
| #include <assert.h> |
| |
| 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( 640, 480, 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_ARB_texture_compression")); |
| assert(hasext(exts, "GL_EXT_texture_compression_s3tc")); |
| |
| // Set the OpenGL state after creating the context with SDL_SetVideoMode |
| |
| glClearColor( 0, 0, 0, 0 ); |
| |
| glEnable( GL_TEXTURE_2D ); // Needed when we're using the fixed-function pipeline. |
| |
| glViewport( 0, 0, 640, 480 ); |
| |
| glMatrixMode( GL_PROJECTION ); |
| GLfloat matrixData[] = { 2.0/640, 0, 0, 0, |
| 0, -2.0/480, 0, 0, |
| 0, 0, -1, 0, |
| -1, 1, 0, 1 }; |
| glLoadMatrixf(matrixData); // test loadmatrix |
| |
| glMatrixMode( GL_MODELVIEW ); |
| glLoadIdentity(); |
| |
| |
| // Load the OpenGL texture |
| |
| GLuint texture; |
| |
| #define DDS_SIZE 262272 |
| FILE *dds = fopen("screenshot.dds", "rb"); |
| char *ddsdata = (char*)malloc(512*512*4);//DDS_SIZE); |
| assert(fread(ddsdata, 1, DDS_SIZE, dds) == DDS_SIZE); |
| fclose(dds); |
| |
| glGenTextures( 1, &texture ); |
| glBindTexture( GL_TEXTURE_2D, texture ); |
| |
| assert(!glGetError()); |
| glCompressedTexImage2D(GL_TEXTURE_2D, 0, GL_COMPRESSED_RGBA_S3TC_DXT5_EXT, 512, 512, 0, DDS_SIZE-128, ddsdata+128); |
| assert(!glGetError()); |
| |
| glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR ); |
| glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR ); |
| |
| |
| // Prepare and Render |
| |
| // Clear the screen before drawing |
| glClear( GL_COLOR_BUFFER_BIT ); |
| |
| // Bind the texture to which subsequent calls refer to |
| glBindTexture( GL_TEXTURE_2D, texture ); |
| |
| // Use clientside vertex pointers to render two items |
| GLfloat vertexData[] = { 0, 0, 10, 10, // texture2, position2 |
| 1, 0, 300, 10, |
| 1, 1, 300, 128, |
| 0, 1, 10, 128, |
| 0, 0.5, 410, 10, |
| 1, 0.5, 600, 10, |
| 1, 1, 630, 200, |
| 0.5, 1, 310, 250 }; |
| |
| glEnableClientState(GL_TEXTURE_COORD_ARRAY); |
| glTexCoordPointer(2, GL_FLOAT, 4*4, &vertexData[0]); |
| glEnableClientState(GL_VERTEX_ARRAY); |
| glVertexPointer(2, GL_FLOAT, 4*4, &vertexData[2]); |
| |
| glDrawArrays(GL_QUADS, 0, 8); |
| |
| glDisableClientState(GL_TEXTURE_COORD_ARRAY); |
| glDisableClientState(GL_VERTEX_ARRAY); |
| |
| // Render the last item using oldschool glBegin etc |
| glBegin( GL_TRIANGLE_STRIP ); |
| glTexCoord2i( 0, 0 ); glVertex3f( 100, 300, 0 ); |
| glTexCoord2i( 1, 0 ); glVertex3f( 300, 300, 0 ); |
| glTexCoord2i( 1, 1 ); glVertex3f( 300, 400, 0 ); |
| glTexCoord2i( 0, 1 ); glVertex3f( 500, 410, 0 ); |
| glEnd(); |
| |
| SDL_GL_SwapBuffers(); |
| |
| #ifndef __EMSCRIPTEN__ |
| // Wait for 3 seconds to give us a chance to see the image |
| SDL_Delay(1500); |
| #endif |
| |
| // Now we can delete the OpenGL texture and close down SDL |
| glDeleteTextures( 1, &texture ); |
| |
| SDL_Quit(); |
| |
| return 0; |
| } |