progs/tests/tex1d.c

   1
   2 /* Exercise 1D textures
   3  */
   4
   5 #include <assert.h>
   6 #include <math.h>
   7 #include <stdio.h>
   8 #include <stdlib.h>
   9 #include <string.h>
  10 #include "GL/glut.h"
  11
  12 static GLuint Window = 0;
  13 static GLuint TexObj[2];
  14 static GLfloat Angle = 0.0f;
  15
  16
  17 static void draw( void )
  18 {
  19    glClear( GL_COLOR_BUFFER_BIT );
  20
  21    glColor3f( 1.0, 1.0, 1.0 );
  22
  23    /* draw first polygon */
  24    glPushMatrix();
  25    glTranslatef( -1.0, 0.0, 0.0 );
  26    glRotatef( Angle, 0.0, 0.0, 1.0 );
  27    glBindTexture( GL_TEXTURE_1D, TexObj[0] );
  28    glBegin( GL_POLYGON );
  29    glTexCoord1f( 0.0 );   glVertex2f( -1.0, -1.0 );
  30    glTexCoord1f( 1.0 );   glVertex2f(  1.0, -1.0 );
  31    glTexCoord1f( 1.0 );   glVertex2f(  1.0,  1.0 );
  32    glTexCoord1f( 0.0 );   glVertex2f( -1.0,  1.0 );
  33    glEnd();
  34    glPopMatrix();
  35
  36    glutSwapBuffers();
  37 }
  38
  39
  40
  41 static void idle( void )
  42 {
  43    Angle += 2.0;
  44    glutPostRedisplay();
  45 }
  46
  47
  48
  49 /* change view Angle, exit upon ESC */
  50 static void key(unsigned char k, int x, int y)
  51 {
  52    (void) x;
  53    (void) y;
  54    switch (k) {
  55       case 27:
  56          exit(0);
  57    }
  58 }
  59
  60
  61
  62 /* new window size or exposure */
  63 static void reshape( int width, int height )
  64 {
  65    glViewport(0, 0, (GLint)width, (GLint)height);
  66    glMatrixMode(GL_PROJECTION);
  67    glLoadIdentity();
  68    /*   glOrtho( -3.0, 3.0, -3.0, 3.0, -10.0, 10.0 );*/
  69    glFrustum( -2.0, 2.0, -2.0, 2.0, 6.0, 20.0 );
  70    glMatrixMode(GL_MODELVIEW);
  71    glLoadIdentity();
  72    glTranslatef( 0.0, 0.0, -8.0 );
  73 }
  74
  75
  76 static void init( void )
  77 {
  78    GLubyte tex[256][3];
  79    GLint i;
  80
  81
  82    glDisable( GL_DITHER );
  83
  84    /* Setup texturing */
  85    glEnable( GL_TEXTURE_1D );
  86    glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL );
  87
  88
  89    /* generate texture object IDs */
  90    glGenTextures( 2, TexObj );
  91
  92    /* setup first texture object */
  93    glBindTexture( GL_TEXTURE_1D, TexObj[0] );
  94
  95
  96    for (i = 0; i < 256; i++) {
  97       GLfloat f;
  98
  99       /* map 0..255 to -PI .. PI */
 100       f = ((i / 255.0) - .5) * (3.141592 * 2);
 101
 102       f = sin(f);
 103
 104       /* map -1..1 to 0..255 */
 105       tex[i][0] = (f+1.0)/2.0 * 255.0;
 106       tex[i][1] = 0;
 107       tex[i][2] = 0;
 108    }
 109
 110    glTexImage1D( GL_TEXTURE_1D, 0, 3, 256, 0, GL_RGB, GL_UNSIGNED_BYTE, tex );
 111    glTexParameteri( GL_TEXTURE_1D, GL_TEXTURE_MIN_FILTER, GL_NEAREST );
 112    glTexParameteri( GL_TEXTURE_1D, GL_TEXTURE_MAG_FILTER, GL_NEAREST );
 113    glTexParameteri( GL_TEXTURE_1D, GL_TEXTURE_WRAP_S, GL_REPEAT );
 114    glTexParameteri( GL_TEXTURE_1D, GL_TEXTURE_WRAP_T, GL_REPEAT );
 115 }
 116
 117
 118
 119 int main( int argc, char *argv[] )
 120 {
 121    glutInit(&argc, argv);
 122    glutInitWindowPosition(0, 0);
 123    glutInitWindowSize(300, 300);
 124    glutInitDisplayMode( GLUT_RGB | GLUT_DEPTH | GLUT_DOUBLE );
 125
 126    Window = glutCreateWindow("Texture Objects");
 127    if (!Window) {
 128       exit(1);
 129    }
 130
 131    init();
 132
 133    glutReshapeFunc( reshape );
 134    glutKeyboardFunc( key );
 135 /*    glutIdleFunc( idle ); */
 136    glutDisplayFunc( draw );
 137    glutMainLoop();
 138    return 0;
 139 }