progs/demos/winpos.c

   1
   2 /*
   3  * Example of how to use the GL_MESA_window_pos extension.
   4  * Brian Paul   This file is in the public domain.
   5  */
   6
   7 #include <math.h>
   8 #include <string.h>
   9 #include <stdlib.h>
  10 #include <stdio.h>
  11 #ifdef _WIN32
  12 #include <windows.h>
  13 #endif
  14 #define GL_GLEXT_PROTOTYPES
  15 #include "GL/glut.h"
  16
  17 #include "readtex.h"
  18
  19 #define IMAGE_FILE "../images/girl.rgb"
  20
  21
  22 #ifndef M_PI
  23 #  define M_PI 3.14159265
  24 #endif
  25
  26
  27
  28 static GLubyte *Image;
  29 static int ImgWidth, ImgHeight;
  30 static GLenum ImgFormat;
  31
  32 typedef void (APIENTRY * PFNWINDOWPOSFUNC)(GLfloat x, GLfloat y);
  33 static PFNWINDOWPOSFUNC WindowPosFunc;
  34
  35 static void draw( void )
  36 {
  37    GLfloat angle;
  38
  39    glClear( GL_COLOR_BUFFER_BIT );
  40
  41    for (angle = -45.0; angle <= 135.0; angle += 10.0) {
  42       GLfloat x = 50.0 + 200.0 * cos( angle * M_PI / 180.0 );
  43       GLfloat y = 50.0 + 200.0 * sin( angle * M_PI / 180.0 );
  44
  45       /* Don't need to worry about the modelview or projection matrices!!! */
  46       (*WindowPosFunc)( x, y );
  47
  48       glDrawPixels( ImgWidth, ImgHeight, ImgFormat, GL_UNSIGNED_BYTE, Image );
  49    }
  50    glFinish();
  51 }
  52
  53
  54 static void key( unsigned char key, int x, int y )
  55 {
  56    (void) x;
  57    (void) y;
  58    switch (key) {
  59       case 27:
  60          exit(0);
  61    }
  62 }
  63
  64
  65 /* new window size or exposure */
  66 static void reshape( int width, int height )
  67 {
  68    glViewport(0, 0, (GLint)width, (GLint)height);
  69 }
  70
  71
  72 static void init( void )
  73 {
  74 #ifdef GL_ARB_window_pos
  75    if (glutExtensionSupported("GL_ARB_window_pos")) {
  76       printf("Using GL_ARB_window_pos\n");
  77       WindowPosFunc = &glWindowPos2fARB;
  78    }
  79    else
  80 #elif defined(GL_MESA_window_pos)
  81    if (glutExtensionSupported("GL_MESA_window_pos")) {
  82       printf("Using GL_MESA_window_pos\n");
  83       WindowPosFunc = &glWindowPos2fMESA;
  84    }
  85    else
  86 #endif
  87    {
  88       printf("Sorry, GL_ARB/MESA_window_pos extension not available.\n");
  89       exit(1);
  90    }
  91
  92    Image = LoadRGBImage( IMAGE_FILE, &ImgWidth, &ImgHeight, &ImgFormat );
  93    if (!Image) {
  94       printf("Couldn't read %s\n", IMAGE_FILE);
  95       exit(0);
  96    }
  97    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
  98 }
  99
 100
 101 int main( int argc, char *argv[] )
 102 {
 103    glutInit(&argc, argv);
 104    glutInitWindowPosition(0, 0);
 105    glutInitWindowSize(500, 500);
 106    glutInitDisplayMode( GLUT_RGB );
 107
 108    if (glutCreateWindow("winpos") <= 0) {
 109       exit(0);
 110    }
 111
 112    init();
 113
 114    glutReshapeFunc( reshape );
 115    glutKeyboardFunc( key );
 116    glutDisplayFunc( draw );
 117    glutMainLoop();
 118    return 0;
 119 }