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Very basic SDL2 OpenGL application
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <math.h>
#include <SDL2/SDL.h>
#include <SDL2/SDL_opengl.h>
void Display_InitGL()
{
/* Enable smooth shading */
glShadeModel( GL_SMOOTH );
/* Set the background black */
glClearColor( 0.0f, 0.0f, 0.0f, 0.0f );
/* Depth buffer setup */
glClearDepth( 1.0f );
/* Enables Depth Testing */
glEnable( GL_DEPTH_TEST );
/* The Type Of Depth Test To Do */
glDepthFunc( GL_LEQUAL );
/* Really Nice Perspective Calculations */
glHint( GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST );
}
/* function to reset our viewport after a window resize */
int Display_SetViewport( int width, int height )
{
/* Height / width ration */
GLfloat ratio;
/* Protect against a divide by zero */
if ( height == 0 ) {
height = 1;
}
ratio = ( GLfloat )width / ( GLfloat )height;
/* Setup our viewport. */
glViewport( 0, 0, ( GLsizei )width, ( GLsizei )height );
/* change to the projection matrix and set our viewing volume. */
glMatrixMode( GL_PROJECTION );
glLoadIdentity( );
/* Set our perspective */
gluPerspective( 45.0f, ratio, 0.1f, 100.0f );
/* Make sure we're chaning the model view and not the projection */
glMatrixMode( GL_MODELVIEW );
/* Reset The View */
glLoadIdentity( );
return 1;
}
void Display_Render()
{
/* Set the background black */
glClearColor( 0.0f, 0.0f, 0.0f, 0.0f );
/* Clear The Screen And The Depth Buffer */
glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
/* Move Left 1.5 Units And Into The Screen 6.0 */
glLoadIdentity();
glTranslatef( -1.5f, 0.0f, -6.0f );
glBegin( GL_TRIANGLES ); /* Drawing Using Triangles */
glVertex3f( 0.0f, 1.0f, 0.0f ); /* Top */
glVertex3f( -1.0f, -1.0f, 0.0f ); /* Bottom Left */
glVertex3f( 1.0f, -1.0f, 0.0f ); /* Bottom Right */
glEnd( ); /* Finished Drawing The Triangle */
/* Move Right 3 Units */
glTranslatef( 3.0f, 0.0f, 0.0f );
glBegin( GL_QUADS ); /* Draw A Quad */
glVertex3f( -1.0f, 1.0f, 0.0f ); /* Top Left */
glVertex3f( 1.0f, 1.0f, 0.0f ); /* Top Right */
glVertex3f( 1.0f, -1.0f, 0.0f ); /* Bottom Right */
glVertex3f( -1.0f, -1.0f, 0.0f ); /* Bottom Left */
glEnd( ); /* Done Drawing The Quad */
SDL_RenderPresent(displayRenderer);
}
int
main(int argc, char *argv[])
{
SDL_Init(SDL_INIT_VIDEO);
SDL_Window* displayWindow;
SDL_Renderer* displayRenderer;
SDL_RendererInfo displayRendererInfo;
SDL_CreateWindowAndRenderer(800, 600, SDL_WINDOW_OPENGL, &displayWindow, &displayRenderer);
SDL_GetRendererInfo(displayRenderer, &displayRendererInfo);
/*TODO: Check that we have OpenGL */
if ((displayRendererInfo.flags & SDL_RENDERER_ACCELERATED) == 0 ||
(displayRendererInfo.flags & SDL_RENDERER_TARGETTEXTURE) == 0) {
/*TODO: Handle this. We have no render surface and not accelerated. */
}
Display_InitGL();
Display_SetViewport(800, 600);
Display_Render();
SDL_Delay(5000);
SDL_Quit();
return 0;
}
@g3ida

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@g3ida g3ida commented Sep 7, 2013

thank you, but your code won't compile. you probably have to declare displayRenderer and displayWindow in the global scope rather than in the main function to fix it.

@mdodkins

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@mdodkins mdodkins commented Nov 27, 2013

you also need to include something for gluPerspective.... gl\glu.h
... and even after that, it didn't work for me, just getting a black screen. The thought was good though :)

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@mdodkins mdodkins commented Nov 28, 2013

For anyone else who finds this and has trouble, I got it working - you need to create an OpenGL context too. After creating the window + renderer, call SDL_GL_CreateContext() passing the window as a parameter. Then, once you've drawn what you want with OpenGL commands, you need to use SDL_GL_SwapWindow().

@JoryRFerrell

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@JoryRFerrell JoryRFerrell commented Jan 2, 2014

Yea...I pushed the renderer and window variables into the global mem, and used a function by NEHE to replace the perspective function: http://nehe.gamedev.net/article/replacement_for_gluperspective/21002/

@constvoidblog

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@constvoidblog constvoidblog commented Jan 5, 2014

for osx 10.9/xcode 5....

sdl2 framework, gl framework, glut framework

line 9: #include OpenGL/glu.h

replace line 63 w/void Display_Render(SDL_Renderer* displayRenderer)

line 114: Display_Render(displayRenderer);

@foxor

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@foxor foxor commented Feb 16, 2014

You don't really need a renderer in SDL2.

line 90: SDL_GL_SwapWindow(displayWindow);

line 101: displayWindow = SDL_CreateWindow("", 0, 0, width, height, SDL_WINDOW_OPENGL);

Delete everywhere else the renderer appears.

@dirkk0

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@dirkk0 dirkk0 commented Jun 28, 2015

Here is a working example for MacOSX and Ubuntu:
https://gist.github.com/dirkk0/cad259e6a3965abb4178

@sergnechaev

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@sergnechaev sergnechaev commented Oct 13, 2015

@haxpor

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@haxpor haxpor commented Sep 24, 2016

SDL2 + OpenGL with event polling (get rid of delay) https://gist.github.com/haxpor/8cd82700b5b6d0a40702901c6bbd6757

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