src/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 #include "glad/glad.h"
  15 #include "glut_wrap.h"
  16
  17 #include "readtex.h"
  18
  19 #define IMAGE_FILE DEMOS_DATA_DIR "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 static PFNGLWINDOWPOS2FPROC WindowPosFunc;
  33
  34 static void draw( void )
  35 {
  36    GLfloat angle;
  37
  38    glClear( GL_COLOR_BUFFER_BIT );
  39
  40    for (angle = -45.0; angle <= 135.0; angle += 10.0) {
  41       GLfloat x = 50.0 + 200.0 * cos( angle * M_PI / 180.0 );
  42       GLfloat y = 50.0 + 200.0 * sin( angle * M_PI / 180.0 );
  43
  44       /* Don't need to worry about the modelview or projection matrices!!! */
  45       (*WindowPosFunc)( x, y );
  46
  47       glDrawPixels( ImgWidth, ImgHeight, ImgFormat, GL_UNSIGNED_BYTE, Image );
  48    }
  49    glFinish();
  50 }
  51
  52
  53 static void key( unsigned char key, int x, int y )
  54 {
  55    (void) x;
  56    (void) y;
  57    switch (key) {
  58       case 27:
  59          exit(0);
  60    }
  61 }
  62
  63
  64 /* new window size or exposure */
  65 static void reshape( int width, int height )
  66 {
  67    glViewport(0, 0, (GLint)width, (GLint)height);
  68 }
  69
  70
  71 static void init( void )
  72 {
  73    if (GLAD_GL_ARB_window_pos) {
  74       printf("Using GL_ARB_window_pos\n");
  75       WindowPosFunc = glWindowPos2fARB;
  76    }
  77    else
  78    if (GLAD_GL_MESA_window_pos) {
  79       printf("Using GL_MESA_window_pos\n");
  80       WindowPosFunc = glWindowPos2fMESA;
  81    }
  82    else
  83    {
  84       printf("Sorry, GL_ARB/MESA_window_pos extension not available.\n");
  85       exit(1);
  86    }
  87
  88    Image = LoadRGBImage( IMAGE_FILE, &ImgWidth, &ImgHeight, &ImgFormat );
  89    if (!Image) {
  90       printf("Couldn't read %s\n", IMAGE_FILE);
  91       exit(0);
  92    }
  93    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
  94 }
  95
  96
  97 int main( int argc, char *argv[] )
  98 {
  99    glutInitWindowSize(500, 500);
 100    glutInit(&argc, argv);
 101    glutInitDisplayMode( GLUT_RGB );
 102
 103    if (glutCreateWindow("winpos") <= 0) {
 104       exit(0);
 105    }
 106
 107    gladLoadGL();
 108
 109    init();
 110
 111    glutReshapeFunc( reshape );
 112    glutKeyboardFunc( key );
 113    glutDisplayFunc( draw );
 114    glutMainLoop();
 115    return 0;
 116 }