153 строки
3.9 KiB
C
153 строки
3.9 KiB
C
/*******************************************************************
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* *
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* Using SDL With OpenGL *
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* *
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* Tutorial by Kyle Foley (sdw) *
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* *
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* http://gpwiki.org/index.php/SDL:Tutorials:Using_SDL_with_OpenGL *
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* *
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*******************************************************************/
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/*
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THIS WORK, INCLUDING THE SOURCE CODE, DOCUMENTATION
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AND RELATED MEDIA AND DATA, IS PLACED INTO THE PUBLIC DOMAIN.
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THE ORIGINAL AUTHOR IS KYLE FOLEY.
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THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY
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OF ANY KIND, NOT EVEN THE IMPLIED WARRANTY OF
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MERCHANTABILITY. THE AUTHOR OF THIS SOFTWARE,
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ASSUMES _NO_ RESPONSIBILITY FOR ANY CONSEQUENCE
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RESULTING FROM THE USE, MODIFICATION, OR
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REDISTRIBUTION OF THIS SOFTWARE.
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*/
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#ifndef __EMSCRIPTEN__
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#define USE_GLEW 0
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#endif
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#if USE_GLEW
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#include "GL/glew.h"
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#endif
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#include "SDL/SDL.h"
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#include "SDL/SDL_image.h"
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#if !USE_GLEW
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#include "SDL/SDL_opengl.h"
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#endif
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#include <stdio.h>
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#include <string.h>
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#include <assert.h>
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int main(int argc, char *argv[])
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{
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SDL_Surface *screen;
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// Slightly different SDL initialization
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if ( SDL_Init(SDL_INIT_VIDEO) != 0 ) {
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printf("Unable to initialize SDL: %s\n", SDL_GetError());
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return 1;
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}
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SDL_GL_SetAttribute( SDL_GL_DOUBLEBUFFER, 1 ); // *new*
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screen = SDL_SetVideoMode( 640, 480, 16, SDL_OPENGL ); // *changed*
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if ( !screen ) {
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printf("Unable to set video mode: %s\n", SDL_GetError());
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return 1;
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}
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// Set the OpenGL state after creating the context with SDL_SetVideoMode
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glClearColor( 0, 0, 0, 0 );
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#ifndef __EMSCRIPTEN__
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glEnable( GL_TEXTURE_2D ); // Need this to display a texture XXX unnecessary in OpenGL ES 2.0/WebGL
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#endif
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glViewport( 0, 0, 640, 480 );
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glMatrixMode( GL_MODELVIEW );
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glLoadIdentity();
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// Clear the screen before drawing
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glClear( GL_COLOR_BUFFER_BIT );
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typedef struct Vertex {
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GLfloat x;
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GLfloat y;
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} Vertex;
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typedef struct Color {
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GLubyte r;
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GLubyte g;
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GLubyte b;
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GLubyte a;
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} Color;
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Vertex vertices[3] = {
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{-1.0, 0.0},
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{ 0.0, 1.0},
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{ 1.0, 0.0}
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};
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Color colors[3] = {
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{0xFF, 0x00, 0x00, 0xFF},
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{0x00, 0xFF, 0x00, 0xFF},
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{0x00, 0x00, 0xFF, 0xFF}
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};
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Vertex vertices2[3] = {
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{-1.0, 0.0},
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{ 1.0, 0.0},
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{ 0.0, -1.0}
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};
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Color colors2[3] = {
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{0xFF, 0x00, 0x00, 0xFF},
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{0x00, 0x00, 0xFF, 0xFF},
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{0x00, 0xFF, 0x00, 0xFF}
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};
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// DRAW
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// Clear the screen before drawing
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glClear( GL_COLOR_BUFFER_BIT );
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// This test ensures that we can use two separate arrays in memory for different
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// attributes, and that they each can have different stride.
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// The first test shows implicit striding (the zero indicates tightly packed)
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// The second test shows explicit striding where the stride is passed in
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// even though it also is tightly packed
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glEnableClientState(GL_VERTEX_ARRAY);
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glEnableClientState(GL_COLOR_ARRAY);
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// TEST 1
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glVertexPointer(2, GL_FLOAT, 0, vertices);
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glColorPointer(4, GL_UNSIGNED_BYTE, 0, colors);
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glDrawArrays(GL_TRIANGLE_STRIP, 0, 3);
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// TEST 2
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glVertexPointer(2, GL_FLOAT, 8, vertices2);
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glColorPointer(4, GL_UNSIGNED_BYTE, 4, colors2);
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glDrawArrays(GL_TRIANGLE_STRIP, 0, 3);
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glDisableClientState(GL_COLOR_ARRAY);
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glDisableClientState(GL_VERTEX_ARRAY);
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SDL_GL_SwapBuffers();
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#ifndef __EMSCRIPTEN__
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// Wait for 3 seconds to give us a chance to see the image
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SDL_Delay(3000);
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#endif
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SDL_Quit();
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return 0;
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}
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