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 <string.h>
  13 #include <GL/glut.h>
  14
  15 #include "readtex.h"
  16
  17 #define IMAGE_FILE "../images/girl.rgb"
  18
  19 static int ImgWidth, ImgHeight;
  20 static int WinWidth, WinHeight;
  21 static GLenum ImgFormat;
  22 static GLubyte *Image = NULL;
  23
  24 static int APosX, APosY;  /* simple drawpixels */
  25 static int BPosX, BPosY;  /* read/draw pixels */
  26 static int CPosX, CPosY;  /* copypixels */
  27
  28 static GLboolean DrawFront = GL_FALSE;
  29 static GLboolean ScaleAndBias = GL_FALSE;
  30 static GLboolean Benchmark = GL_FALSE;
  31 static GLboolean Triangle = GL_FALSE;
  32 static GLubyte *TempImage = NULL;
  33
  34 #define COMBO 1
  35 #if COMBO == 0
  36 #define ReadFormat ImgFormat
  37 #define ReadType GL_UNSIGNED_BYTE
  38 #elif COMBO == 1
  39 static GLenum ReadFormat = GL_RGBA;
  40 static GLenum ReadType = GL_UNSIGNED_BYTE;
  41 #elif COMBO == 2
  42 static GLenum ReadFormat = GL_RGB;
  43 static GLenum ReadType = GL_UNSIGNED_BYTE;
  44 #elif COMBO == 3
  45 static GLenum ReadFormat = GL_RGB;
  46 static GLenum ReadType = GL_UNSIGNED_SHORT_5_6_5;
  47 #elif COMBO == 4
  48 static GLenum ReadFormat = GL_RGBA;
  49 static GLenum ReadType = GL_UNSIGNED_SHORT_1_5_5_5_REV;
  50 #elif COMBO == 5
  51 static GLenum ReadFormat = GL_BGRA;
  52 static GLenum ReadType = GL_UNSIGNED_SHORT_5_5_5_1;
  53 #elif COMBO == 6
  54 static GLenum ReadFormat = GL_BGRA;
  55 static GLenum ReadType = GL_UNSIGNED_SHORT_4_4_4_4_REV;
  56 #elif COMBO == 7
  57 static GLenum ReadFormat = GL_RGBA;
  58 static GLenum ReadType = GL_HALF_FLOAT_ARB;
  59 #undef GL_OES_read_format
  60 #endif
  61
  62
  63 static void
  64 Reset( void )
  65 {
  66    APosX = 5;     APosY = 20;
  67    BPosX = APosX + ImgWidth + 5;   BPosY = 20;
  68    CPosX = BPosX + ImgWidth + 5;   CPosY = 20;
  69 }
  70
  71
  72 static void
  73 PrintString(const char *s)
  74 {
  75    while (*s) {
  76       glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s);
  77       s++;
  78    }
  79 }
  80
  81
  82 static void
  83 SetupPixelTransfer(GLboolean invert)
  84 {
  85    if (invert) {
  86       glPixelTransferf(GL_RED_SCALE, -1.0);
  87       glPixelTransferf(GL_RED_BIAS, 1.0);
  88       glPixelTransferf(GL_GREEN_SCALE, -1.0);
  89       glPixelTransferf(GL_GREEN_BIAS, 1.0);
  90       glPixelTransferf(GL_BLUE_SCALE, -1.0);
  91       glPixelTransferf(GL_BLUE_BIAS, 1.0);
  92    }
  93    else {
  94       glPixelTransferf(GL_RED_SCALE, 1.0);
  95       glPixelTransferf(GL_RED_BIAS, 0.0);
  96       glPixelTransferf(GL_GREEN_SCALE, 1.0);
  97       glPixelTransferf(GL_GREEN_BIAS, 0.0);
  98       glPixelTransferf(GL_BLUE_SCALE, 1.0);
  99       glPixelTransferf(GL_BLUE_BIAS, 0.0);
 100    }
 101 }
 102
 103
 104 /**
 105  * Exercise Pixel Pack parameters by reading the image in four pieces.
 106  */
 107 static void
 108 ComplexReadPixels(GLint x, GLint y, GLsizei width, GLsizei height,
 109                   GLenum format, GLenum type, GLvoid *pixels)
 110 {
 111    const GLsizei width0 = width / 2;
 112    const GLsizei width1 = width - width0;
 113    const GLsizei height0 = height / 2;
 114    const GLsizei height1 = height - height0;
 115
 116    glPixelStorei(GL_PACK_ROW_LENGTH, width);
 117
 118    /* lower-left quadrant */
 119    glReadPixels(x, y, width0, height0, format, type, pixels);
 120
 121    /* lower-right quadrant */
 122    glPixelStorei(GL_PACK_SKIP_PIXELS, width0);
 123    glReadPixels(x + width0, y, width1, height0, format, type, pixels);
 124
 125    /* upper-left quadrant */
 126    glPixelStorei(GL_PACK_SKIP_PIXELS, 0);
 127    glPixelStorei(GL_PACK_SKIP_ROWS, height0);
 128    glReadPixels(x, y + height0, width0, height1, format, type, pixels);
 129
 130    /* upper-right quadrant */
 131    glPixelStorei(GL_PACK_SKIP_PIXELS, width0);
 132    glPixelStorei(GL_PACK_SKIP_ROWS, height0);
 133    glReadPixels(x + width0, y + height0, width1, height1, format, type, pixels);
 134
 135    /* restore defaults */
 136    glPixelStorei(GL_PACK_SKIP_PIXELS, 0);
 137    glPixelStorei(GL_PACK_SKIP_ROWS, 0);
 138    glPixelStorei(GL_PACK_ROW_LENGTH, ImgWidth);
 139 }
 140
 141
 142
 143 static void
 144 Display( void )
 145 {
 146    glClearColor(.3, .3, .3, 1);
 147    glClear( GL_COLOR_BUFFER_BIT );
 148
 149    glRasterPos2i(5, ImgHeight+25);
 150    PrintString("f = toggle front/back  s = toggle scale/bias  b = benchmark");
 151
 152    /* draw original image */
 153    glRasterPos2i(APosX, 5);
 154    PrintString("Original");
 155    if (!Triangle) {
 156       glRasterPos2i(APosX, APosY);
 157       glEnable(GL_DITHER);
 158       SetupPixelTransfer(GL_FALSE);
 159       glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
 160       glDrawPixels(ImgWidth, ImgHeight, ImgFormat, GL_UNSIGNED_BYTE, Image);
 161    }
 162    else {
 163       float z = 0;
 164
 165       glViewport(APosX, APosY, ImgWidth, ImgHeight);
 166       glMatrixMode( GL_PROJECTION );
 167       glLoadIdentity();
 168       glOrtho(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0);
 169       glDisable(GL_CULL_FACE);
 170
 171       /* Red should never be seen
 172        */
 173       glBegin(GL_POLYGON);
 174       glColor3f(1,0,0);
 175       glVertex3f(-2, -2, z);
 176       glVertex3f(-2, 2, z);
 177       glVertex3f(2, 2, z);
 178       glVertex3f(2, -2, z);
 179       glEnd();
 180
 181       /* Blue background
 182        */
 183       glBegin(GL_POLYGON);
 184       glColor3f(.5,.5,1);
 185       glVertex3f(-1, -1, z);
 186       glVertex3f(-1, 1, z);
 187       glVertex3f(1, 1, z);
 188       glVertex3f(1, -1, z);
 189       glEnd();
 190
 191       /* Triangle
 192        */
 193       glBegin(GL_TRIANGLES);
 194       glColor3f(.8,0,0);
 195       glVertex3f(-0.9, -0.9, z);
 196       glColor3f(0,.9,0);
 197       glVertex3f( 0.9, -0.9, z);
 198       glColor3f(0,0,.7);
 199       glVertex3f( 0.0,  0.9, z);
 200       glEnd();
 201
 202       glColor3f(1,1,1);
 203
 204       glViewport( 0, 0, WinWidth, WinHeight );
 205       glMatrixMode( GL_PROJECTION );
 206       glLoadIdentity();
 207       glOrtho( 0.0, WinWidth, 0.0, WinHeight, -1.0, 1.0 );
 208    }
 209
 210    /* might try alignment=4 here for testing */
 211    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
 212    glPixelStorei(GL_PACK_ALIGNMENT, 1);
 213
 214    /* do readpixels, drawpixels */
 215    glRasterPos2i(BPosX, 5);
 216    PrintString("Read/DrawPixels");
 217    SetupPixelTransfer(ScaleAndBias);
 218    if (Benchmark) {
 219       GLint reads = 0;
 220       GLint endTime;
 221       GLint startTime = glutGet(GLUT_ELAPSED_TIME);
 222       GLdouble seconds, pixelsPerSecond;
 223       printf("Benchmarking...\n");
 224       do {
 225          glReadPixels(APosX, APosY, ImgWidth, ImgHeight,
 226                       ReadFormat, ReadType, TempImage);
 227          reads++;
 228          endTime = glutGet(GLUT_ELAPSED_TIME);
 229       } while (endTime - startTime < 4000);   /* 4 seconds */
 230       seconds = (double) (endTime - startTime) / 1000.0;
 231       pixelsPerSecond = reads * ImgWidth * ImgHeight / seconds;
 232       printf("Result:  %d reads in %f seconds = %f pixels/sec\n",
 233              reads, seconds, pixelsPerSecond);
 234       Benchmark = GL_FALSE;
 235    }
 236    else {
 237       /* clear the temporary image to white (helpful for debugging */
 238       memset(TempImage, 255, ImgWidth * ImgHeight * 4);
 239 #if 1
 240       glReadPixels(APosX, APosY, ImgWidth, ImgHeight,
 241                    ReadFormat, ReadType, TempImage);
 242       (void) ComplexReadPixels;
 243 #else
 244       /* you might use this when debugging */
 245       ComplexReadPixels(APosX, APosY, ImgWidth, ImgHeight,
 246                         ReadFormat, ReadType, TempImage);
 247 #endif
 248    }
 249    glRasterPos2i(BPosX, BPosY);
 250    glDisable(GL_DITHER);
 251    SetupPixelTransfer(GL_FALSE);
 252    glDrawPixels(ImgWidth, ImgHeight, ReadFormat, ReadType, TempImage);
 253
 254    /* do copypixels */
 255    glRasterPos2i(CPosX, 5);
 256    PrintString("CopyPixels");
 257    glRasterPos2i(CPosX, CPosY);
 258    glDisable(GL_DITHER);
 259    SetupPixelTransfer(ScaleAndBias);
 260    glCopyPixels(APosX, APosY, ImgWidth, ImgHeight, GL_COLOR);
 261
 262    if (!DrawFront)
 263       glutSwapBuffers();
 264    else
 265       glFinish();
 266 }
 267
 268
 269 static void
 270 Reshape( int width, int height )
 271 {
 272    WinWidth = width;
 273    WinHeight = height;
 274
 275    glViewport( 0, 0, width, height );
 276    glMatrixMode( GL_PROJECTION );
 277    glLoadIdentity();
 278    glOrtho( 0.0, width, 0.0, height, -1.0, 1.0 );
 279    glMatrixMode( GL_MODELVIEW );
 280    glLoadIdentity();
 281 }
 282
 283
 284 static void
 285 Key( unsigned char key, int x, int y )
 286 {
 287    (void) x;
 288    (void) y;
 289    switch (key) {
 290       case 'b':
 291          Benchmark = GL_TRUE;
 292          break;
 293       case 't':
 294          Triangle = !Triangle;
 295          break;
 296       case 's':
 297          ScaleAndBias = !ScaleAndBias;
 298          break;
 299       case 'f':
 300          DrawFront = !DrawFront;
 301          if (DrawFront) {
 302             glDrawBuffer(GL_FRONT);
 303             glReadBuffer(GL_FRONT);
 304          }
 305          else {
 306             glDrawBuffer(GL_BACK);
 307             glReadBuffer(GL_BACK);
 308          }
 309          printf("glDrawBuffer(%s)\n", DrawFront ? "GL_FRONT" : "GL_BACK");
 310          break;
 311       case 27:
 312          exit(0);
 313          break;
 314    }
 315    glutPostRedisplay();
 316 }
 317
 318
 319 static void
 320 Init( GLboolean ciMode )
 321 {
 322    GLboolean have_read_format = GL_FALSE;
 323
 324    printf("GL_VERSION = %s\n", (char *) glGetString(GL_VERSION));
 325    printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
 326
 327    Image = LoadRGBImage( IMAGE_FILE, &ImgWidth, &ImgHeight, &ImgFormat );
 328    if (!Image) {
 329       printf("Couldn't read %s\n", IMAGE_FILE);
 330       exit(0);
 331    }
 332
 333    if (ciMode) {
 334       /* Convert RGB image to grayscale */
 335       GLubyte *indexImage = (GLubyte *) malloc( ImgWidth * ImgHeight );
 336       GLint i;
 337       for (i=0; i<ImgWidth*ImgHeight; i++) {
 338          int gray = Image[i*3] + Image[i*3+1] + Image[i*3+2];
 339          indexImage[i] = gray / 3;
 340       }
 341       free(Image);
 342       Image = indexImage;
 343       ImgFormat = GL_COLOR_INDEX;
 344
 345       for (i=0;i<255;i++) {
 346          float g = i / 255.0;
 347          glutSetColor(i, g, g, g);
 348       }
 349    }
 350
 351 #ifdef GL_OES_read_format
 352    if ( glutExtensionSupported( "GL_OES_read_format" ) ) {
 353       glGetIntegerv(GL_IMPLEMENTATION_COLOR_READ_TYPE_OES,   (GLint *) &ReadType);
 354       glGetIntegerv(GL_IMPLEMENTATION_COLOR_READ_FORMAT_OES, (GLint *) &ReadFormat);
 355
 356       have_read_format = GL_TRUE;
 357    }
 358 #endif
 359
 360    printf( "GL_OES_read_format %ssupported.  "
 361            "Using type / format = 0x%04x / 0x%04x\n",
 362            (have_read_format) ? "" : "not ",
 363            ReadType, ReadFormat );
 364
 365    printf("Loaded %d by %d image\n", ImgWidth, ImgHeight );
 366
 367    glPixelStorei(GL_UNPACK_ROW_LENGTH, ImgWidth);
 368    glPixelStorei(GL_PACK_ROW_LENGTH, ImgWidth);
 369
 370    Reset();
 371
 372    /* allocate large TempImage to store and image data type, plus an
 373     * extra 1KB in case we're tinkering with pack alignment.
 374     */
 375    TempImage = (GLubyte *) malloc(ImgWidth * ImgHeight * 4 * 4
 376                                   + 1000);
 377    assert(TempImage);
 378 }
 379
 380
 381 int
 382 main( int argc, char *argv[] )
 383 {
 384    GLboolean ciMode = GL_FALSE;
 385    if (argc > 1 && strcmp(argv[1], "-ci")==0) {
 386       ciMode = GL_TRUE;
 387    }
 388    glutInit( &argc, argv );
 389    glutInitWindowPosition( 0, 0 );
 390    glutInitWindowSize( 750, 250 );
 391    if (ciMode)
 392       glutInitDisplayMode( GLUT_INDEX | GLUT_DOUBLE );
 393    else
 394       glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE );
 395    glutCreateWindow(argv[0]);
 396    Init(ciMode);
 397    glutReshapeFunc( Reshape );
 398    glutKeyboardFunc( Key );
 399    glutDisplayFunc( Display );
 400    glutMainLoop();
 401    return 0;
 402 }