progs/egl/opengl/egltri.c

   1 /*
   2  * Copyright (C) 2008  Brian Paul   All Rights Reserved.
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice shall be included
  12  * in all copies or substantial portions of the Software.
  13  *
  14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  15  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  17  * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
  18  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  19  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  20  */
  21
  22 /*
  23  * Draw a triangle with X/EGL.
  24  * Brian Paul
  25  * 3 June 2008
  26  */
  27
  28
  29 #include <math.h>
  30 #include <stdlib.h>
  31 #include <string.h>
  32 #include <GL/gl.h>
  33
  34 #include "eglut.h"
  35
  36
  37 static GLfloat view_rotx = 0.0, view_roty = 0.0, view_rotz = 0.0;
  38
  39
  40 static void
  41 draw(void)
  42 {
  43    static const GLfloat verts[3][2] = {
  44       { -1, -1 },
  45       {  1, -1 },
  46       {  0,  1 }
  47    };
  48    static const GLfloat colors[3][3] = {
  49       { 1, 0, 0 },
  50       { 0, 1, 0 },
  51       { 0, 0, 1 }
  52    };
  53
  54    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  55
  56    glPushMatrix();
  57    glRotatef(view_rotx, 1, 0, 0);
  58    glRotatef(view_roty, 0, 1, 0);
  59    glRotatef(view_rotz, 0, 0, 1);
  60
  61    {
  62       glVertexPointer(2, GL_FLOAT, 0, verts);
  63       glColorPointer(3, GL_FLOAT, 0, colors);
  64       glEnableClientState(GL_VERTEX_ARRAY);
  65       glEnableClientState(GL_COLOR_ARRAY);
  66
  67       glDrawArrays(GL_TRIANGLES, 0, 3);
  68
  69       glDisableClientState(GL_VERTEX_ARRAY);
  70       glDisableClientState(GL_COLOR_ARRAY);
  71    }
  72
  73    glPopMatrix();
  74 }
  75
  76
  77 /* new window size or exposure */
  78 static void
  79 reshape(int width, int height)
  80 {
  81    GLfloat ar = (GLfloat) width / (GLfloat) height;
  82
  83    glViewport(0, 0, (GLint) width, (GLint) height);
  84
  85    glMatrixMode(GL_PROJECTION);
  86    glLoadIdentity();
  87    glFrustum(-ar, ar, -1, 1, 5.0, 60.0);
  88
  89    glMatrixMode(GL_MODELVIEW);
  90    glLoadIdentity();
  91    glTranslatef(0.0, 0.0, -10.0);
  92 }
  93
  94
  95 static void
  96 init(void)
  97 {
  98    glClearColor(0.4, 0.4, 0.4, 0.0);
  99 }
 100
 101
 102 static void
 103 special_key(int special)
 104 {
 105    switch (special) {
 106    case EGLUT_KEY_LEFT:
 107       view_roty += 5.0;
 108       break;
 109    case EGLUT_KEY_RIGHT:
 110       view_roty -= 5.0;
 111       break;
 112    case EGLUT_KEY_UP:
 113       view_rotx += 5.0;
 114       break;
 115    case EGLUT_KEY_DOWN:
 116       view_rotx -= 5.0;
 117       break;
 118    default:
 119       break;
 120    }
 121 }
 122
 123 int
 124 main(int argc, char *argv[])
 125 {
 126    eglutInitWindowSize(300, 300);
 127    eglutInitAPIMask(EGLUT_OPENGL_BIT);
 128    eglutInit(argc, argv);
 129
 130    eglutCreateWindow("egltri");
 131
 132    eglutReshapeFunc(reshape);
 133    eglutDisplayFunc(draw);
 134    eglutSpecialFunc(special_key);
 135
 136    init();
 137
 138    eglutMainLoop();
 139
 140    return 0;
 141 }