progs/demos/readpix.c

   1
   2 /*
   3  * glReadPixels and glCopyPixels test
   4  *
   5  * Brian Paul   March 1, 2000  This file is in the public domain.
   6  */
   7
   8 #include <assert.h>
   9 #include <stdio.h>
  10 #include <stdlib.h>
  11 #include <math.h>
  12 #include <GL/glut.h>
  13
  14 #include "../util/readtex.c"  /* a hack, I know */
  15
  16 #define IMAGE_FILE "../images/girl.rgb"
  17
  18 static int ImgWidth, ImgHeight;
  19 static GLenum ImgFormat;
  20 static GLubyte *Image = NULL;
  21
  22 static int APosX, APosY;  /* simple drawpixels */
  23 static int BPosX, BPosY;  /* read/draw pixels */
  24 static int CPosX, CPosY;  /* copypixels */
  25
  26 static GLboolean DrawFront = GL_FALSE;
  27 static GLboolean ScaleAndBias = GL_FALSE;
  28 static GLboolean Benchmark = GL_FALSE;
  29 static GLubyte *TempImage = NULL;
  30
  31 #if 0
  32 #define ReadFormat ImgFormat
  33 #define ReadType GL_UNSIGNED_BYTE
  34 #endif
  35 #if 1
  36 static GLenum ReadFormat = GL_RGBA;
  37 static GLenum ReadType = GL_UNSIGNED_BYTE;
  38 #endif
  39 #if 0
  40 static GLenum ReadFormat = GL_RGB;
  41 static GLenum ReadType = GL_UNSIGNED_SHORT_5_6_5;
  42 #endif
  43 #if 0
  44 static GLenum ReadFormat = GL_RGBA;
  45 static GLenum ReadType = GL_UNSIGNED_SHORT_1_5_5_5_REV;
  46 #endif
  47 #if 0
  48 static GLenum ReadFormat = GL_BGRA;
  49 static GLenum ReadType = GL_UNSIGNED_SHORT_5_5_5_1;
  50 #endif
  51 #if 0
  52 static GLenum ReadFormat = GL_BGRA;
  53 static GLenum ReadType = GL_UNSIGNED_SHORT_4_4_4_4_REV;
  54 #endif
  55
  56
  57 static void
  58 Reset( void )
  59 {
  60    APosX = 5;     APosY = 20;
  61    BPosX = APosX + ImgWidth + 5;   BPosY = 20;
  62    CPosX = BPosX + ImgWidth + 5;   CPosY = 20;
  63 }
  64
  65
  66 static void
  67 PrintString(const char *s)
  68 {
  69    while (*s) {
  70       glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s);
  71       s++;
  72    }
  73 }
  74
  75
  76 static void
  77 SetupPixelTransfer(GLboolean invert)
  78 {
  79    if (invert) {
  80       glPixelTransferf(GL_RED_SCALE, -1.0);
  81       glPixelTransferf(GL_RED_BIAS, 1.0);
  82       glPixelTransferf(GL_GREEN_SCALE, -1.0);
  83       glPixelTransferf(GL_GREEN_BIAS, 1.0);
  84       glPixelTransferf(GL_BLUE_SCALE, -1.0);
  85       glPixelTransferf(GL_BLUE_BIAS, 1.0);
  86    }
  87    else {
  88       glPixelTransferf(GL_RED_SCALE, 1.0);
  89       glPixelTransferf(GL_RED_BIAS, 0.0);
  90       glPixelTransferf(GL_GREEN_SCALE, 1.0);
  91       glPixelTransferf(GL_GREEN_BIAS, 0.0);
  92       glPixelTransferf(GL_BLUE_SCALE, 1.0);
  93       glPixelTransferf(GL_BLUE_BIAS, 0.0);
  94    }
  95 }
  96
  97
  98 static void
  99 Display( void )
 100 {
 101    glClearColor(.3, .3, .3, 1);
 102    glClear( GL_COLOR_BUFFER_BIT );
 103
 104    glRasterPos2i(5, ImgHeight+25);
 105    PrintString("f = toggle front/back  s = toggle scale/bias  b = benchmark");
 106
 107    /* draw original image */
 108    glRasterPos2i(APosX, 5);
 109    PrintString("Original");
 110    glRasterPos2i(APosX, APosY);
 111    glEnable(GL_DITHER);
 112    SetupPixelTransfer(GL_FALSE);
 113    glDrawPixels(ImgWidth, ImgHeight, ImgFormat, GL_UNSIGNED_BYTE, Image);
 114
 115    /* do readpixels, drawpixels */
 116    glRasterPos2i(BPosX, 5);
 117    PrintString("Read/DrawPixels");
 118    SetupPixelTransfer(ScaleAndBias);
 119    if (Benchmark) {
 120       GLint reads = 0;
 121       GLint endTime;
 122       GLint startTime = glutGet(GLUT_ELAPSED_TIME);
 123       GLdouble seconds, pixelsPerSecond;
 124       printf("Benchmarking...\n");
 125       do {
 126          glReadPixels(APosX, APosY, ImgWidth, ImgHeight,
 127                       ReadFormat, ReadType, TempImage);
 128          reads++;
 129          endTime = glutGet(GLUT_ELAPSED_TIME);
 130       } while (endTime - startTime < 4000);   /* 4 seconds */
 131       seconds = (double) (endTime - startTime) / 1000.0;
 132       pixelsPerSecond = reads * ImgWidth * ImgHeight / seconds;
 133       printf("Result:  %d reads in %f seconds = %f pixels/sec\n",
 134              reads, seconds, pixelsPerSecond);
 135       Benchmark = GL_FALSE;
 136    }
 137    else {
 138       /* clear the temporary image to white (helpful for debugging */
 139       memset(TempImage, 255, ImgWidth * ImgHeight * 4);
 140       glReadPixels(APosX, APosY, ImgWidth, ImgHeight,
 141                    ReadFormat, ReadType, TempImage);
 142    }
 143    glRasterPos2i(BPosX, BPosY);
 144    glDisable(GL_DITHER);
 145    SetupPixelTransfer(GL_FALSE);
 146    glDrawPixels(ImgWidth, ImgHeight, ReadFormat, ReadType, TempImage);
 147
 148    /* do copypixels */
 149    glRasterPos2i(CPosX, 5);
 150    PrintString("CopyPixels");
 151    glRasterPos2i(CPosX, CPosY);
 152    glDisable(GL_DITHER);
 153    SetupPixelTransfer(ScaleAndBias);
 154    glCopyPixels(APosX, APosY, ImgWidth, ImgHeight, GL_COLOR);
 155
 156    if (!DrawFront)
 157       glutSwapBuffers();
 158    else
 159       glFinish();
 160 }
 161
 162
 163 static void
 164 Reshape( int width, int height )
 165 {
 166    glViewport( 0, 0, width, height );
 167    glMatrixMode( GL_PROJECTION );
 168    glLoadIdentity();
 169    glOrtho( 0.0, width, 0.0, height, -1.0, 1.0 );
 170    glMatrixMode( GL_MODELVIEW );
 171    glLoadIdentity();
 172 }
 173
 174
 175 static void
 176 Key( unsigned char key, int x, int y )
 177 {
 178    (void) x;
 179    (void) y;
 180    switch (key) {
 181       case 'b':
 182          Benchmark = GL_TRUE;
 183          break;
 184       case 's':
 185          ScaleAndBias = !ScaleAndBias;
 186          break;
 187       case 'f':
 188          DrawFront = !DrawFront;
 189          if (DrawFront) {
 190             glDrawBuffer(GL_FRONT);
 191             glReadBuffer(GL_FRONT);
 192          }
 193          else {
 194             glDrawBuffer(GL_BACK);
 195             glReadBuffer(GL_BACK);
 196          }
 197          printf("glDrawBuffer(%s)\n", DrawFront ? "GL_FRONT" : "GL_BACK");
 198          break;
 199       case 27:
 200          exit(0);
 201          break;
 202    }
 203    glutPostRedisplay();
 204 }
 205
 206
 207 static void
 208 Init( GLboolean ciMode )
 209 {
 210    GLboolean have_read_format = GL_FALSE;
 211
 212    printf("GL_VERSION = %s\n", (char *) glGetString(GL_VERSION));
 213    printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
 214
 215    Image = LoadRGBImage( IMAGE_FILE, &ImgWidth, &ImgHeight, &ImgFormat );
 216    if (!Image) {
 217       printf("Couldn't read %s\n", IMAGE_FILE);
 218       exit(0);
 219    }
 220
 221    if (ciMode) {
 222       /* Convert RGB image to grayscale */
 223       GLubyte *indexImage = (GLubyte *) malloc( ImgWidth * ImgHeight );
 224       GLint i;
 225       for (i=0; i<ImgWidth*ImgHeight; i++) {
 226          int gray = Image[i*3] + Image[i*3+1] + Image[i*3+2];
 227          indexImage[i] = gray / 3;
 228       }
 229       free(Image);
 230       Image = indexImage;
 231       ImgFormat = GL_COLOR_INDEX;
 232
 233       for (i=0;i<255;i++) {
 234          float g = i / 255.0;
 235          glutSetColor(i, g, g, g);
 236       }
 237    }
 238
 239 #ifdef GL_OES_read_format
 240    if ( glutExtensionSupported( "GL_OES_read_format" ) ) {
 241       glGetIntegerv(GL_IMPLEMENTATION_COLOR_READ_TYPE_OES,   (GLint *) &ReadType);
 242       glGetIntegerv(GL_IMPLEMENTATION_COLOR_READ_FORMAT_OES, (GLint *) &ReadFormat);
 243
 244       have_read_format = GL_TRUE;
 245    }
 246 #endif
 247
 248    printf( "GL_OES_read_format %ssupported.  "
 249            "Using type / format = 0x%04x / 0x%04x\n",
 250            (have_read_format) ? "" : "not ",
 251            ReadType, ReadFormat );
 252
 253    printf("Loaded %d by %d image\n", ImgWidth, ImgHeight );
 254
 255    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
 256    glPixelStorei(GL_UNPACK_ROW_LENGTH, ImgWidth);
 257    glPixelStorei(GL_PACK_ALIGNMENT, 1);
 258    glPixelStorei(GL_PACK_ROW_LENGTH, ImgWidth);
 259
 260    Reset();
 261
 262    TempImage = (GLubyte *) malloc(ImgWidth * ImgHeight * 4 * sizeof(GLubyte));
 263    assert(TempImage);
 264 }
 265
 266
 267 int
 268 main( int argc, char *argv[] )
 269 {
 270    GLboolean ciMode = GL_FALSE;
 271    if (argc > 1 && strcmp(argv[1], "-ci")==0) {
 272       ciMode = GL_TRUE;
 273    }
 274    glutInit( &argc, argv );
 275    glutInitWindowPosition( 0, 0 );
 276    glutInitWindowSize( 750, 250 );
 277    if (ciMode)
 278       glutInitDisplayMode( GLUT_INDEX | GLUT_DOUBLE );
 279    else
 280       glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE );
 281    glutCreateWindow(argv[0]);
 282    Init(ciMode);
 283    glutReshapeFunc( Reshape );
 284    glutKeyboardFunc( Key );
 285    glutDisplayFunc( Display );
 286    glutMainLoop();
 287    return 0;
 288 }