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 "glut_wrap.h"
14
15#include "readtex.h"
16
17#define IMAGE_FILE DEMOS_DATA_DIR "girl.rgb"
18
19static int ImgWidth, ImgHeight;
20static int WinWidth, WinHeight;
21static GLenum ImgFormat;
22static GLubyte *Image = NULL;
23
24static int APosX, APosY;  /* simple drawpixels */
25static int BPosX, BPosY;  /* read/draw pixels */
26static int CPosX, CPosY;  /* copypixels */
27
28static GLboolean DrawFront = GL_FALSE;
29static GLboolean ScaleAndBias = GL_FALSE;
30static GLboolean Benchmark = GL_FALSE;
31static GLboolean Triangle = GL_FALSE;
32static 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
39static GLenum ReadFormat = GL_RGBA;
40static GLenum ReadType = GL_UNSIGNED_BYTE;
41#elif COMBO == 2
42static GLenum ReadFormat = GL_RGB;
43static GLenum ReadType = GL_UNSIGNED_BYTE;
44#elif COMBO == 3
45static GLenum ReadFormat = GL_RGB;
46static GLenum ReadType = GL_UNSIGNED_SHORT_5_6_5;
47#elif COMBO == 4
48static GLenum ReadFormat = GL_RGBA;
49static GLenum ReadType = GL_UNSIGNED_SHORT_1_5_5_5_REV;
50#elif COMBO == 5
51static GLenum ReadFormat = GL_BGRA;
52static GLenum ReadType = GL_UNSIGNED_SHORT_5_5_5_1;
53#elif COMBO == 6
54static GLenum ReadFormat = GL_BGRA;
55static GLenum ReadType = GL_UNSIGNED_SHORT_4_4_4_4_REV;
56#elif COMBO == 7
57static GLenum ReadFormat = GL_RGBA;
58static GLenum ReadType = GL_HALF_FLOAT_ARB;
59#undef GL_OES_read_format
60#endif
61
62
63static void
64Reset( void )
65{
66   APosX = 5;     APosY = 20;
67   BPosX = APosX + ImgWidth + 5;   BPosY = 20;
68   CPosX = BPosX + ImgWidth + 5;   CPosY = 20;
69}
70
71
72static void
73PrintString(const char *s)
74{
75   while (*s) {
76      glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s);
77      s++;
78   }
79}
80
81
82static void
83SetupPixelTransfer(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 */
107static void
108ComplexReadPixels(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
143static void
144Display( 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, mpixels, mpixelsPerSecond;
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      mpixels = reads * (ImgWidth * ImgHeight / (1000.0 * 1000.0));
232      mpixelsPerSecond = mpixels / seconds;
233      printf("Result:  %d reads in %f seconds = %f Mpixels/sec\n",
234             reads, seconds, mpixelsPerSecond);
235      Benchmark = GL_FALSE;
236   }
237   else {
238      /* clear the temporary image to white (helpful for debugging */
239      memset(TempImage, 255, ImgWidth * ImgHeight * 4);
240#if 1
241      glReadPixels(APosX, APosY, ImgWidth, ImgHeight,
242                   ReadFormat, ReadType, TempImage);
243      (void) ComplexReadPixels;
244#else
245      /* you might use this when debugging */
246      ComplexReadPixels(APosX, APosY, ImgWidth, ImgHeight,
247                        ReadFormat, ReadType, TempImage);
248#endif
249   }
250   glRasterPos2i(BPosX, BPosY);
251   glDisable(GL_DITHER);
252   SetupPixelTransfer(GL_FALSE);
253   glDrawPixels(ImgWidth, ImgHeight, ReadFormat, ReadType, TempImage);
254
255   /* do copypixels */
256   glRasterPos2i(CPosX, 5);
257   PrintString("CopyPixels");
258   glRasterPos2i(CPosX, CPosY);
259   glDisable(GL_DITHER);
260   SetupPixelTransfer(ScaleAndBias);
261   glCopyPixels(APosX, APosY, ImgWidth, ImgHeight, GL_COLOR);
262
263   if (!DrawFront)
264      glutSwapBuffers();
265   else
266      glFinish();
267}
268
269
270static void
271Reshape( int width, int height )
272{
273   WinWidth = width;
274   WinHeight = height;
275
276   glViewport( 0, 0, width, height );
277   glMatrixMode( GL_PROJECTION );
278   glLoadIdentity();
279   glOrtho( 0.0, width, 0.0, height, -1.0, 1.0 );
280   glMatrixMode( GL_MODELVIEW );
281   glLoadIdentity();
282}
283
284
285static void
286Key( unsigned char key, int x, int y )
287{
288   (void) x;
289   (void) y;
290   switch (key) {
291      case 'b':
292         Benchmark = GL_TRUE;
293         break;
294      case 't':
295         Triangle = !Triangle;
296         break;
297      case 's':
298         ScaleAndBias = !ScaleAndBias;
299         break;
300      case 'f':
301         DrawFront = !DrawFront;
302         if (DrawFront) {
303            glDrawBuffer(GL_FRONT);
304            glReadBuffer(GL_FRONT);
305         }
306         else {
307            glDrawBuffer(GL_BACK);
308            glReadBuffer(GL_BACK);
309         }
310         printf("glDrawBuffer(%s)\n", DrawFront ? "GL_FRONT" : "GL_BACK");
311         break;
312      case 27:
313         exit(0);
314         break;
315   }
316   glutPostRedisplay();
317}
318
319
320static void
321Init( GLboolean ciMode )
322{
323   GLboolean have_read_format = GL_FALSE;
324
325   printf("GL_VERSION = %s\n", (char *) glGetString(GL_VERSION));
326   printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
327
328   Image = LoadRGBImage( IMAGE_FILE, &ImgWidth, &ImgHeight, &ImgFormat );
329   if (!Image) {
330      printf("Couldn't read %s\n", IMAGE_FILE);
331      exit(0);
332   }
333
334   if (ciMode) {
335      /* Convert RGB image to grayscale */
336      GLubyte *indexImage = (GLubyte *) malloc( ImgWidth * ImgHeight );
337      GLint i;
338      for (i=0; i<ImgWidth*ImgHeight; i++) {
339         int gray = Image[i*3] + Image[i*3+1] + Image[i*3+2];
340         indexImage[i] = gray / 3;
341      }
342      free(Image);
343      Image = indexImage;
344      ImgFormat = GL_COLOR_INDEX;
345
346      for (i=0;i<255;i++) {
347         float g = i / 255.0;
348         glutSetColor(i, g, g, g);
349      }
350   }
351
352#ifdef GL_OES_read_format
353   if ( glutExtensionSupported( "GL_OES_read_format" ) ) {
354      glGetIntegerv(GL_IMPLEMENTATION_COLOR_READ_TYPE_OES,   (GLint *) &ReadType);
355      glGetIntegerv(GL_IMPLEMENTATION_COLOR_READ_FORMAT_OES, (GLint *) &ReadFormat);
356
357      have_read_format = GL_TRUE;
358   }
359#endif
360
361   printf( "GL_OES_read_format %ssupported.  "
362	   "Using type / format = 0x%04x / 0x%04x\n",
363	   (have_read_format) ? "" : "not ",
364	   ReadType, ReadFormat );
365
366   printf("Loaded %d by %d image\n", ImgWidth, ImgHeight );
367
368   glPixelStorei(GL_UNPACK_ROW_LENGTH, ImgWidth);
369   glPixelStorei(GL_PACK_ROW_LENGTH, ImgWidth);
370
371   Reset();
372
373   /* allocate large TempImage to store and image data type, plus an
374    * extra 1KB in case we're tinkering with pack alignment.
375    */
376   TempImage = (GLubyte *) malloc(ImgWidth * ImgHeight * 4 * 4
377                                  + 1000);
378   assert(TempImage);
379}
380
381
382int
383main( int argc, char *argv[] )
384{
385   GLboolean ciMode = GL_FALSE;
386   glutInitWindowSize( 750, 250 );
387   glutInit( &argc, argv );
388   if (argc > 1 && strcmp(argv[1], "-ci")==0) {
389      ciMode = GL_TRUE;
390   }
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}
403