progs/demos/readpix.c

   1 /* $Id: readpix.c,v 1.8 2002/07/12 15:54:02 brianp Exp $ */
   2
   3 /*
   4  * glReadPixels and glCopyPixels test
   5  *
   6  * Brian Paul   March 1, 2000  This file is in the public domain.
   7  */
   8
   9 #include <assert.h>
  10 #include <stdio.h>
  11 #include <stdlib.h>
  12 #include <math.h>
  13 #include <GL/glut.h>
  14
  15 #include "../util/readtex.c"  /* a hack, I know */
  16
  17 #define IMAGE_FILE "../images/girl.rgb"
  18
  19 static int ImgWidth, ImgHeight;
  20 static GLenum ImgFormat;
  21 static GLubyte *Image = NULL;
  22
  23 static int APosX, APosY;  /* simple drawpixels */
  24 static int BPosX, BPosY;  /* read/draw pixels */
  25 static int CPosX, CPosY;  /* copypixels */
  26
  27 static GLboolean DrawFront = GL_FALSE;
  28 static GLboolean ScaleAndBias = GL_FALSE;
  29 static GLboolean Benchmark = GL_FALSE;
  30 static GLubyte *TempImage = NULL;
  31
  32 #if 0
  33 #define ReadFormat ImgFormat
  34 #define ReadType GL_UNSIGNED_BYTE
  35 #endif
  36 #if 1
  37 static GLenum ReadFormat = GL_RGBA;
  38 static GLenum ReadType = GL_UNSIGNED_BYTE;
  39 #endif
  40 #if 0
  41 static GLenum ReadFormat = GL_RGB;
  42 static GLenum ReadType = GL_UNSIGNED_SHORT_5_6_5;
  43 #endif
  44 #if 0
  45 static GLenum ReadFormat = GL_RGBA;
  46 static GLenum ReadType = GL_UNSIGNED_SHORT_1_5_5_5_REV;
  47 #endif
  48 #if 0
  49 static GLenum ReadFormat = GL_BGRA;
  50 static GLenum ReadType = GL_UNSIGNED_SHORT_5_5_5_1;
  51 #endif
  52 #if 0
  53 static GLenum ReadFormat = GL_BGRA;
  54 static GLenum ReadType = GL_UNSIGNED_SHORT_4_4_4_4_REV;
  55 #endif
  56
  57
  58 static void
  59 Reset( void )
  60 {
  61    APosX = 5;     APosY = 20;
  62    BPosX = APosX + ImgWidth + 5;   BPosY = 20;
  63    CPosX = BPosX + ImgWidth + 5;   CPosY = 20;
  64 }
  65
  66
  67 static void
  68 PrintString(const char *s)
  69 {
  70    while (*s) {
  71       glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s);
  72       s++;
  73    }
  74 }
  75
  76
  77 static void
  78 SetupPixelTransfer(GLboolean invert)
  79 {
  80    if (invert) {
  81       glPixelTransferf(GL_RED_SCALE, -1.0);
  82       glPixelTransferf(GL_RED_BIAS, 1.0);
  83       glPixelTransferf(GL_GREEN_SCALE, -1.0);
  84       glPixelTransferf(GL_GREEN_BIAS, 1.0);
  85       glPixelTransferf(GL_BLUE_SCALE, -1.0);
  86       glPixelTransferf(GL_BLUE_BIAS, 1.0);
  87    }
  88    else {
  89       glPixelTransferf(GL_RED_SCALE, 1.0);
  90       glPixelTransferf(GL_RED_BIAS, 0.0);
  91       glPixelTransferf(GL_GREEN_SCALE, 1.0);
  92       glPixelTransferf(GL_GREEN_BIAS, 0.0);
  93       glPixelTransferf(GL_BLUE_SCALE, 1.0);
  94       glPixelTransferf(GL_BLUE_BIAS, 0.0);
  95    }
  96 }
  97
  98
  99 static void
 100 Display( void )
 101 {
 102    glClearColor(.3, .3, .3, 1);
 103    glClear( GL_COLOR_BUFFER_BIT );
 104
 105    glRasterPos2i(5, ImgHeight+25);
 106    PrintString("f = toggle front/back  s = toggle scale/bias  b = benchmark");
 107
 108    /* draw original image */
 109    glRasterPos2i(APosX, 5);
 110    PrintString("Original");
 111    glRasterPos2i(APosX, APosY);
 112    glEnable(GL_DITHER);
 113    SetupPixelTransfer(GL_FALSE);
 114    glDrawPixels(ImgWidth, ImgHeight, ImgFormat, GL_UNSIGNED_BYTE, Image);
 115
 116    /* do readpixels, drawpixels */
 117    glRasterPos2i(BPosX, 5);
 118    PrintString("Read/DrawPixels");
 119    SetupPixelTransfer(ScaleAndBias);
 120    if (Benchmark) {
 121       GLint reads = 0;
 122       GLint endTime;
 123       GLint startTime = glutGet(GLUT_ELAPSED_TIME);
 124       GLdouble seconds, pixelsPerSecond;
 125       printf("Benchmarking...\n");
 126       do {
 127          glReadPixels(APosX, APosY, ImgWidth, ImgHeight,
 128                       ReadFormat, ReadType, TempImage);
 129          reads++;
 130          endTime = glutGet(GLUT_ELAPSED_TIME);
 131       } while (endTime - startTime < 4000);   /* 4 seconds */
 132       seconds = (double) (endTime - startTime) / 1000.0;
 133       pixelsPerSecond = reads * ImgWidth * ImgHeight / seconds;
 134       printf("Result:  %d reads in %f seconds = %f pixels/sec\n",
 135              reads, seconds, pixelsPerSecond);
 136       Benchmark = GL_FALSE;
 137    }
 138    else {
 139       /* clear the temporary image to white (helpful for debugging */
 140       memset(TempImage, 255, ImgWidth * ImgHeight * 4);
 141       glReadPixels(APosX, APosY, ImgWidth, ImgHeight,
 142                    ReadFormat, ReadType, TempImage);
 143    }
 144    glRasterPos2i(BPosX, BPosY);
 145    glDisable(GL_DITHER);
 146    SetupPixelTransfer(GL_FALSE);
 147    glDrawPixels(ImgWidth, ImgHeight, ReadFormat, ReadType, TempImage);
 148
 149    /* do copypixels */
 150    glRasterPos2i(CPosX, 5);
 151    PrintString("CopyPixels");
 152    glRasterPos2i(CPosX, CPosY);
 153    glDisable(GL_DITHER);
 154    SetupPixelTransfer(ScaleAndBias);
 155    glCopyPixels(APosX, APosY, ImgWidth, ImgHeight, GL_COLOR);
 156
 157    if (!DrawFront)
 158       glutSwapBuffers();
 159    else
 160       glFinish();
 161 }
 162
 163
 164 static void
 165 Reshape( int width, int height )
 166 {
 167    glViewport( 0, 0, width, height );
 168    glMatrixMode( GL_PROJECTION );
 169    glLoadIdentity();
 170    glOrtho( 0.0, width, 0.0, height, -1.0, 1.0 );
 171    glMatrixMode( GL_MODELVIEW );
 172    glLoadIdentity();
 173 }
 174
 175
 176 static void
 177 Key( unsigned char key, int x, int y )
 178 {
 179    (void) x;
 180    (void) y;
 181    switch (key) {
 182       case 'b':
 183          Benchmark = GL_TRUE;
 184          break;
 185       case 's':
 186          ScaleAndBias = !ScaleAndBias;
 187          break;
 188       case 'f':
 189          DrawFront = !DrawFront;
 190          if (DrawFront) {
 191             glDrawBuffer(GL_FRONT);
 192             glReadBuffer(GL_FRONT);
 193          }
 194          else {
 195             glDrawBuffer(GL_BACK);
 196             glReadBuffer(GL_BACK);
 197          }
 198          printf("glDrawBuffer(%s)\n", DrawFront ? "GL_FRONT" : "GL_BACK");
 199          break;
 200       case 27:
 201          exit(0);
 202          break;
 203    }
 204    glutPostRedisplay();
 205 }
 206
 207
 208 static void
 209 Init( GLboolean ciMode )
 210 {
 211    printf("GL_VERSION = %s\n", (char *) glGetString(GL_VERSION));
 212    printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
 213
 214    Image = LoadRGBImage( IMAGE_FILE, &ImgWidth, &ImgHeight, &ImgFormat );
 215    if (!Image) {
 216       printf("Couldn't read %s\n", IMAGE_FILE);
 217       exit(0);
 218    }
 219
 220    if (ciMode) {
 221       /* Convert RGB image to grayscale */
 222       GLubyte *indexImage = (GLubyte *) malloc( ImgWidth * ImgHeight );
 223       GLint i;
 224       for (i=0; i<ImgWidth*ImgHeight; i++) {
 225          int gray = Image[i*3] + Image[i*3+1] + Image[i*3+2];
 226          indexImage[i] = gray / 3;
 227       }
 228       free(Image);
 229       Image = indexImage;
 230       ImgFormat = GL_COLOR_INDEX;
 231
 232       for (i=0;i<255;i++) {
 233          float g = i / 255.0;
 234          glutSetColor(i, g, g, g);
 235       }
 236    }
 237
 238    printf("Loaded %d by %d image\n", ImgWidth, ImgHeight );
 239
 240    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
 241    glPixelStorei(GL_UNPACK_ROW_LENGTH, ImgWidth);
 242    glPixelStorei(GL_PACK_ALIGNMENT, 1);
 243    glPixelStorei(GL_PACK_ROW_LENGTH, ImgWidth);
 244
 245    Reset();
 246
 247    TempImage = (GLubyte *) malloc(ImgWidth * ImgHeight * 4 * sizeof(GLubyte));
 248    assert(TempImage);
 249 }
 250
 251
 252 int
 253 main( int argc, char *argv[] )
 254 {
 255    GLboolean ciMode = GL_FALSE;
 256    if (argc > 1 && strcmp(argv[1], "-ci")==0) {
 257       ciMode = GL_TRUE;
 258    }
 259    glutInit( &argc, argv );
 260    glutInitWindowPosition( 0, 0 );
 261    glutInitWindowSize( 750, 250 );
 262    if (ciMode)
 263       glutInitDisplayMode( GLUT_INDEX | GLUT_DOUBLE );
 264    else
 265       glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE );
 266    glutCreateWindow(argv[0]);
 267    Init(ciMode);
 268    glutReshapeFunc( Reshape );
 269    glutKeyboardFunc( Key );
 270    glutDisplayFunc( Display );
 271    glutMainLoop();
 272    return 0;
 273 }