| /******************************************************************* |
| * * |
| * 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 "SDL2/SDL.h" |
| #include "SDL2/SDL_image.h" |
| #include "SDL2/SDL_opengl.h" |
| |
| #include <stdio.h> |
| #include <string.h> |
| #include <assert.h> |
| |
| int main(int argc, char *argv[]) |
| { |
| SDL_Window *window; |
| SDL_GLContext context; |
| |
| // 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* |
| |
| window = SDL_CreateWindow("sdl_fog_density", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 640, 480, SDL_WINDOW_OPENGL); |
| if ( !window ) { |
| printf("Unable to create window: %s\n", SDL_GetError()); |
| return 1; |
| } |
| |
| context = SDL_GL_CreateContext(window); |
| |
| // 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 ); |
| glPushMatrix(); // just for testing |
| glLoadIdentity(); |
| |
| glOrtho( 0, 640, 480, 0, -1000, 1000 ); |
| |
| glMatrixMode( GL_MODELVIEW ); |
| glLoadIdentity(); |
| |
| // Load the OpenGL texture |
| |
| GLuint texture; // Texture object handle |
| SDL_Surface *surface; // Gives us the information to make the texture |
| |
| if ( (surface = IMG_Load("screenshot.png")) ) { |
| |
| // Check that the image's width is a power of 2 |
| if ( (surface->w & (surface->w - 1)) != 0 ) { |
| printf("warning: image.bmp's width is not a power of 2\n"); |
| } |
| |
| // Also check if the height is a power of 2 |
| if ( (surface->h & (surface->h - 1)) != 0 ) { |
| printf("warning: image.bmp's height is not a power of 2\n"); |
| } |
| |
| // Have OpenGL generate a texture object handle for us |
| glGenTextures( 1, &texture ); |
| |
| // Bind the texture object |
| glBindTexture( GL_TEXTURE_2D, texture ); |
| |
| // Set the texture's stretching properties |
| glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR ); |
| glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR ); |
| |
| //SDL_LockSurface(surface); |
| |
| // Add some greyness |
| memset(surface->pixels, 0x66, surface->w*surface->h); |
| |
| // Edit the texture object's image data using the information SDL_Surface gives us |
| glTexImage2D( GL_TEXTURE_2D, 0, GL_RGBA, surface->w, surface->h, 0, |
| GL_RGBA, GL_UNSIGNED_BYTE, surface->pixels ); |
| |
| //SDL_UnlockSurface(surface); |
| } |
| else { |
| printf("SDL could not load image.bmp: %s\n", SDL_GetError()); |
| SDL_Quit(); |
| return 1; |
| } |
| |
| // Free the SDL_Surface only if it was successfully created |
| if ( surface ) { |
| SDL_FreeSurface( surface ); |
| } |
| |
| // Clear the screen before drawing |
| glClear( GL_COLOR_BUFFER_BIT ); |
| |
| // Bind the texture to which subsequent calls refer to |
| glBindTexture( GL_TEXTURE_2D, texture ); |
| |
| glEnable(GL_FOG); |
| GLfloat fogColor[] = { 1.0, 0.5, 0.5, 0.05 }; |
| glFogfv(GL_FOG_COLOR, fogColor); |
| glFogf(GL_FOG_DENSITY, 0.2); |
| glFogi(GL_FOG_MODE, GL_EXP2); |
| |
| assert(glIsEnabled(GL_FOG)); |
| |
| glBegin( GL_QUADS ); |
| glTexCoord2i( 0, 0 ); glVertex3f( 10, 10, 10 ); |
| glTexCoord2i( 1, 0 ); glVertex3f( 300, 10, 10 ); |
| glTexCoord2i( 1, 1 ); glVertex3f( 300, 128, 10 ); |
| glTexCoord2i( 0, 1 ); glVertex3f( 10, 128, 10 ); |
| |
| glTexCoord2f( 0, 0.5 ); glVertex3f( 410, 10, 5 ); |
| glTexCoord2f( 1, 0.5 ); glVertex3f( 600, 10, 6 ); |
| glTexCoord2f( 1, 1 ); glVertex3f( 630, 200, 7 ); |
| glTexCoord2f( 0.5, 1 ); glVertex3f( 310, 250, 8 ); |
| glEnd(); |
| |
| glBegin( GL_TRIANGLE_STRIP ); |
| glTexCoord2i( 0, 0 ); glVertex3f( 100, 300, 1 ); |
| glTexCoord2i( 1, 0 ); glVertex3f( 300, 300, 1 ); |
| glTexCoord2i( 1, 1 ); glVertex3f( 300, 400, 1 ); |
| glTexCoord2i( 0, 1 ); glVertex3f( 500, 410, 1 ); |
| glEnd(); |
| |
| glDisable(GL_TEXTURE_2D); |
| |
| glColor3ub(90, 255, 255); |
| glBegin( GL_QUADS ); |
| glVertex3f( 10, 410, 5 ); |
| glVertex3f( 300, 410, 50 ); |
| glVertex3f( 300, 480, 100 ); |
| glVertex3f( 10, 470, 5 ); |
| glEnd(); |
| |
| glBegin( GL_QUADS ); |
| glColor3f(1.0, 0, 1.0); glVertex3f( 410, 410, 10 ); |
| glColor3f(0, 1.0, 0); glVertex3f( 600, 410, 10 ); |
| glColor3f(0, 0, 1.0); glVertex3f( 600, 480, 10 ); |
| glColor3f(1.0, 1.0, 1.0); glVertex3f( 410, 470, 10 ); |
| glEnd(); |
| |
| SDL_GL_SwapWindow(window); |
| |
| #if !defined(__EMSCRIPTEN__) |
| // Wait for 3 seconds to give us a chance to see the image |
| SDL_Delay(30000); |
| #endif |
| |
| // Now we can delete the OpenGL texture and close down SDL |
| glDeleteTextures( 1, &texture ); |
| |
| // Don't quit - we need to reftest the canvas! SDL_Quit(); |
| |
| return 0; |
| } |