progs/demos/copypix.c

   1 /**
   2  * glCopyPixels test
   3  *
   4  * Brian Paul
   5  * 14 Sep 2007
   6  */
   7
   8
   9 #include <stdio.h>
  10 #include <stdlib.h>
  11 #include <string.h>
  12 #include <GL/glew.h>
  13 #include <GL/glut.h>
  14
  15 #include "readtex.h"
  16
  17 #define IMAGE_FILE "../images/arch.rgb"
  18
  19 static int ImgWidth, ImgHeight;
  20 static GLenum ImgFormat;
  21 static GLubyte *Image = NULL;
  22
  23 static int WinWidth = 800, WinHeight = 800;
  24 static int Xpos, Ypos;
  25 static int Scissor = 0;
  26 static float Xzoom, Yzoom;
  27 static GLboolean DrawFront = GL_FALSE;
  28 static GLboolean Dither = GL_TRUE;
  29 static GLboolean Invert = GL_FALSE;
  30
  31
  32 static void Reset( void )
  33 {
  34    Xpos = Ypos = 20;
  35    Scissor = 0;
  36    Xzoom = Yzoom = 1.0;
  37 }
  38
  39
  40 static void Display( void )
  41 {
  42    const int dx = (WinWidth - ImgWidth) / 2;
  43    const int dy = (WinHeight - ImgHeight) / 2;
  44
  45    if (DrawFront) {
  46       glDrawBuffer(GL_FRONT);
  47       glReadBuffer(GL_FRONT);
  48    }
  49    else {
  50       glDrawBuffer(GL_BACK);
  51       glReadBuffer(GL_BACK);
  52    }
  53
  54    glClear( GL_COLOR_BUFFER_BIT );
  55
  56    /* draw original image */
  57    glWindowPos2iARB(dx, dy);
  58    glDrawPixels(ImgWidth, ImgHeight, ImgFormat, GL_UNSIGNED_BYTE, Image);
  59
  60    if (Scissor)
  61       glEnable(GL_SCISSOR_TEST);
  62
  63    if (Invert) {
  64       glPixelTransferf(GL_RED_SCALE, -1.0);
  65       glPixelTransferf(GL_GREEN_SCALE, -1.0);
  66       glPixelTransferf(GL_BLUE_SCALE, -1.0);
  67       glPixelTransferf(GL_RED_BIAS, 1.0);
  68       glPixelTransferf(GL_GREEN_BIAS, 1.0);
  69       glPixelTransferf(GL_BLUE_BIAS, 1.0);
  70    }
  71
  72    /* draw copy */
  73    glPixelZoom(Xzoom, Yzoom);
  74    glWindowPos2iARB(Xpos, Ypos);
  75    glCopyPixels(dx, dy, ImgWidth, ImgHeight, GL_COLOR);
  76    glPixelZoom(1, 1);
  77
  78    glDisable(GL_SCISSOR_TEST);
  79
  80    if (Invert) {
  81       glPixelTransferf(GL_RED_SCALE, 1.0);
  82       glPixelTransferf(GL_GREEN_SCALE, 1.0);
  83       glPixelTransferf(GL_BLUE_SCALE, 1.0);
  84       glPixelTransferf(GL_RED_BIAS, 0.0);
  85       glPixelTransferf(GL_GREEN_BIAS, 0.0);
  86       glPixelTransferf(GL_BLUE_BIAS, 0.0);
  87    }
  88
  89    if (DrawFront)
  90       glFinish();
  91    else
  92       glutSwapBuffers();
  93 }
  94
  95
  96 static void Reshape( int width, int height )
  97 {
  98    WinWidth = width;
  99    WinHeight = height;
 100
 101    glViewport( 0, 0, width, height );
 102    glMatrixMode( GL_PROJECTION );
 103    glLoadIdentity();
 104    glOrtho( 0.0, width, 0.0, height, 0.0, 2.0 );
 105    glMatrixMode( GL_MODELVIEW );
 106    glLoadIdentity();
 107
 108    glScissor(width/4, height/4, width/2, height/2);
 109 }
 110
 111
 112 static void Key( unsigned char key, int x, int y )
 113 {
 114    (void) x;
 115    (void) y;
 116    switch (key) {
 117       case ' ':
 118          Reset();
 119          break;
 120       case 'd':
 121          Dither = !Dither;
 122          if (Dither)
 123             glEnable(GL_DITHER);
 124          else
 125             glDisable(GL_DITHER);
 126          break;
 127       case 'i':
 128          Invert = !Invert;
 129          break;
 130       case 's':
 131          Scissor = !Scissor;
 132          break;
 133       case 'x':
 134          Xzoom -= 0.1;
 135          break;
 136       case 'X':
 137          Xzoom += 0.1;
 138          break;
 139       case 'y':
 140          Yzoom -= 0.1;
 141          break;
 142       case 'Y':
 143          Yzoom += 0.1;
 144          break;
 145       case 'f':
 146          DrawFront = !DrawFront;
 147          printf("glDrawBuffer(%s)\n", DrawFront ? "GL_FRONT" : "GL_BACK");
 148          break;
 149       case 27:
 150          exit(0);
 151          break;
 152    }
 153    glutPostRedisplay();
 154 }
 155
 156
 157 static void SpecialKey( int key, int x, int y )
 158 {
 159    const int step = (glutGetModifiers() & GLUT_ACTIVE_SHIFT) ? 10 : 1;
 160    (void) x;
 161    (void) y;
 162    switch (key) {
 163       case GLUT_KEY_UP:
 164          Ypos += step;
 165          break;
 166       case GLUT_KEY_DOWN:
 167          Ypos -= step;
 168          break;
 169       case GLUT_KEY_LEFT:
 170          Xpos -= step;
 171          break;
 172       case GLUT_KEY_RIGHT:
 173          Xpos += step;
 174          break;
 175    }
 176    glutPostRedisplay();
 177 }
 178
 179
 180 static void Init( GLboolean ciMode, const char *filename )
 181 {
 182    printf("GL_VERSION = %s\n", (char *) glGetString(GL_VERSION));
 183    printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
 184
 185    Image = LoadRGBImage( filename, &ImgWidth, &ImgHeight, &ImgFormat );
 186    if (!Image) {
 187       printf("Couldn't read %s\n", filename);
 188       exit(0);
 189    }
 190
 191    if (ciMode) {
 192       /* Convert RGB image to grayscale */
 193       GLubyte *indexImage = (GLubyte *) malloc( ImgWidth * ImgHeight );
 194       GLint i;
 195       for (i=0; i<ImgWidth*ImgHeight; i++) {
 196          int gray = Image[i*3] + Image[i*3+1] + Image[i*3+2];
 197          indexImage[i] = gray / 3;
 198       }
 199       free(Image);
 200       Image = indexImage;
 201       ImgFormat = GL_COLOR_INDEX;
 202
 203       for (i=0;i<255;i++) {
 204          float g = i / 255.0;
 205          glutSetColor(i, g, g, g);
 206       }
 207    }
 208
 209    printf("Loaded %d by %d image\n", ImgWidth, ImgHeight );
 210
 211    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
 212    glPixelStorei(GL_UNPACK_ROW_LENGTH, ImgWidth);
 213
 214    Reset();
 215 }
 216
 217
 218 static void Usage(void)
 219 {
 220    printf("Keys:\n");
 221    printf("       SPACE  Reset Parameters\n");
 222    printf("     Up/Down  Move image up/down (SHIFT for large step)\n");
 223    printf("  Left/Right  Move image left/right (SHIFT for large step)\n");
 224    printf("           x  Decrease X-axis PixelZoom\n");
 225    printf("           X  Increase X-axis PixelZoom\n");
 226    printf("           y  Decrease Y-axis PixelZoom\n");
 227    printf("           Y  Increase Y-axis PixelZoom\n");
 228    printf("           s  Toggle GL_SCISSOR_TEST\n");
 229    printf("           f  Toggle front/back buffer drawing\n");
 230    printf("         ESC  Exit\n");
 231 }
 232
 233
 234 int main( int argc, char *argv[] )
 235 {
 236    GLboolean ciMode = GL_FALSE;
 237    const char *filename = IMAGE_FILE;
 238    int i = 1;
 239
 240    glutInitWindowSize( WinWidth, WinHeight );
 241    glutInit( &argc, argv );
 242
 243    if (argc > i && strcmp(argv[i], "-ci")==0) {
 244       ciMode = GL_TRUE;
 245       i++;
 246    }
 247    if (argc > i) {
 248       filename = argv[i];
 249    }
 250
 251    if (ciMode)
 252       glutInitDisplayMode( GLUT_INDEX | GLUT_DOUBLE );
 253    else
 254       glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE);
 255
 256    glutCreateWindow(argv[0]);
 257    glewInit();
 258
 259    Init(ciMode, filename);
 260    Usage();
 261
 262    glutReshapeFunc( Reshape );
 263    glutKeyboardFunc( Key );
 264    glutSpecialFunc( SpecialKey );
 265    glutDisplayFunc( Display );
 266
 267    glutMainLoop();
 268    return 0;
 269 }