| /******************************************************************* |
| * * |
| * 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. |
| */ |
| |
| #ifndef __EMSCRIPTEN__ |
| #define USE_GLEW 0 |
| #endif |
| |
| #if USE_GLEW |
| #include "GL/glew.h" |
| #endif |
| |
| #include <SDL/SDL.h> |
| |
| #if !USE_GLEW |
| #include "SDL/SDL_opengl.h" |
| #endif |
| |
| #include <stdio.h> |
| #include <string.h> |
| #include <assert.h> |
| |
| 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; |
| } |
| |
| // Set the OpenGL state after creating the context with SDL_SetVideoMode |
| |
| glClearColor( 0, 0, 0, 0 ); |
| |
| #ifndef __EMSCRIPTEN__ |
| glEnable( GL_TEXTURE_2D ); // Need this to display a texture XXX unnecessary in OpenGL ES 2.0/WebGL |
| #endif |
| |
| glViewport( 0, 0, 640, 480 ); |
| |
| glMatrixMode( GL_MODELVIEW ); |
| glLoadIdentity(); |
| |
| // Clear the screen before drawing |
| glClear( GL_COLOR_BUFFER_BIT ); |
| |
| typedef struct Color { |
| GLubyte r; |
| GLubyte g; |
| GLubyte b; |
| GLubyte a; |
| } Color; |
| |
| typedef struct Vertex { |
| GLfloat x; |
| GLfloat y; |
| Color color; |
| } Vertex; |
| |
| Vertex vertices[18] = { |
| {-1.00, 0.0, {0xFF, 0x00, 0xFF, 0xFF}}, |
| {-1.00, 1.0, {0xFF, 0xFF, 0x00, 0xFF}}, |
| {-0.75, 0.0, {0xFF, 0x00, 0x00, 0xFF}}, |
| {-0.75, 1.0, {0xFF, 0xFF, 0xFF, 0xFF}}, |
| {-0.50, 0.0, {0xFF, 0x00, 0x00, 0xFF}}, |
| {-0.50, 1.0, {0xFF, 0xFF, 0x00, 0xFF}}, |
| {-0.25, 0.0, {0xFF, 0x00, 0xFF, 0xFF}}, |
| {-0.25, 1.0, {0xFF, 0xFF, 0x00, 0xFF}}, |
| {-0.00, 0.0, {0xFF, 0x00, 0x00, 0xFF}}, |
| {-0.00, 1.0, {0xFF, 0xFF, 0xFF, 0xFF}}, |
| { 0.25, 0.0, {0xFF, 0x00, 0x00, 0xFF}}, |
| { 0.25, 1.0, {0xFF, 0xFF, 0x00, 0xFF}}, |
| { 0.50, 0.0, {0xFF, 0x00, 0xFF, 0xFF}}, |
| { 0.50, 1.0, {0xFF, 0xFF, 0x00, 0xFF}}, |
| { 0.75, 0.0, {0xFF, 0x00, 0x00, 0xFF}}, |
| { 0.75, 1.0, {0xFF, 0xFF, 0xFF, 0xFF}}, |
| { 1.00, 0.0, {0xFF, 0x00, 0x00, 0xFF}}, |
| { 1.00, 1.0, {0xFF, 0xFF, 0x00, 0xFF}} |
| }; |
| |
| Vertex vertices2[18] = { |
| {-1.00, -1.0, {0xFF, 0x00, 0xFF, 0xFF}}, |
| {-1.00, 0.0, {0xFF, 0xFF, 0x00, 0xFF}}, |
| {-0.75, -1.0, {0xFF, 0x00, 0x00, 0xFF}}, |
| {-0.75, 0.0, {0xFF, 0xFF, 0xFF, 0xFF}}, |
| {-0.50, -1.0, {0xFF, 0x00, 0x00, 0xFF}}, |
| {-0.50, 0.0, {0xFF, 0xFF, 0x00, 0xFF}}, |
| {-0.25, -1.0, {0xFF, 0x00, 0xFF, 0xFF}}, |
| {-0.25, 0.0, {0xFF, 0xFF, 0x00, 0xFF}}, |
| {-0.00, -1.0, {0xFF, 0x00, 0x00, 0xFF}}, |
| {-0.00, 0.0, {0xFF, 0xFF, 0xFF, 0xFF}}, |
| { 0.25, -1.0, {0xFF, 0x00, 0x00, 0xFF}}, |
| { 0.25, 0.0, {0xFF, 0xFF, 0x00, 0xFF}}, |
| { 0.50, -1.0, {0xFF, 0x00, 0xFF, 0xFF}}, |
| { 0.50, 0.0, {0xFF, 0xFF, 0x00, 0xFF}}, |
| { 0.75, -1.0, {0xFF, 0x00, 0x00, 0xFF}}, |
| { 0.75, 0.0, {0xFF, 0xFF, 0xFF, 0xFF}}, |
| { 1.00, -1.0, {0xFF, 0x00, 0x00, 0xFF}}, |
| { 1.00, 0.0, {0xFF, 0xFF, 0x00, 0xFF}} |
| }; |
| |
| // make a vertex buffer for the second set of vertices |
| GLuint vbo = 0; |
| glGenBuffers(1, &vbo); |
| |
| |
| // bind to it |
| glBindBuffer(GL_ARRAY_BUFFER, vbo); |
| // send it to gl |
| glBufferData(GL_ARRAY_BUFFER, sizeof(vertices2), vertices2, GL_STATIC_DRAW); |
| |
| // unbind from it |
| glBindBuffer(GL_ARRAY_BUFFER, 0); |
| |
| |
| // DRAW |
| |
| // Clear the screen before drawing |
| glClear( GL_COLOR_BUFFER_BIT ); |
| |
| // This test ensures that we can use two separate arrays in memory for different |
| // attributes, and that they each can have different stride. |
| |
| glEnableClientState(GL_VERTEX_ARRAY); |
| glEnableClientState(GL_COLOR_ARRAY); |
| |
| glVertexPointer(2, GL_FLOAT, sizeof(Vertex), vertices); |
| glColorPointer(4, GL_UNSIGNED_BYTE, sizeof(Vertex), &vertices[0].color); |
| glDrawArrays(GL_TRIANGLE_STRIP, 10, 3); |
| glDrawArrays(GL_TRIANGLE_STRIP, 0, 6); |
| |
| glBindBuffer(GL_ARRAY_BUFFER, 0); |
| |
| glDisableClientState(GL_COLOR_ARRAY); |
| glDisableClientState(GL_VERTEX_ARRAY); |
| |
| SDL_GL_SwapBuffers(); |
| |
| #ifndef __EMSCRIPTEN__ |
| // Wait for 3 seconds to give us a chance to see the image |
| SDL_Delay(3000); |
| #endif |
| |
| SDL_Quit(); |
| |
| return 0; |
| } |