3 * glReadPixels and glCopyPixels test
5 * Brian Paul March 1, 2000 This file is in the public domain.
17 #define IMAGE_FILE "../images/girl.rgb"
19 static int ImgWidth, ImgHeight;
20 static GLenum ImgFormat;
21 static GLubyte *Image = NULL;
23 static int APosX, APosY; /* simple drawpixels */
24 static int BPosX, BPosY; /* read/draw pixels */
25 static int CPosX, CPosY; /* copypixels */
27 static GLboolean DrawFront = GL_FALSE;
28 static GLboolean ScaleAndBias = GL_FALSE;
29 static GLboolean Benchmark = GL_FALSE;
30 static GLubyte *TempImage = NULL;
34 #define ReadFormat ImgFormat
35 #define ReadType GL_UNSIGNED_BYTE
37 static GLenum ReadFormat = GL_RGBA;
38 static GLenum ReadType = GL_UNSIGNED_BYTE;
40 static GLenum ReadFormat = GL_RGB;
41 static GLenum ReadType = GL_UNSIGNED_BYTE;
43 static GLenum ReadFormat = GL_RGB;
44 static GLenum ReadType = GL_UNSIGNED_SHORT_5_6_5;
46 static GLenum ReadFormat = GL_RGBA;
47 static GLenum ReadType = GL_UNSIGNED_SHORT_1_5_5_5_REV;
49 static GLenum ReadFormat = GL_BGRA;
50 static GLenum ReadType = GL_UNSIGNED_SHORT_5_5_5_1;
52 static GLenum ReadFormat = GL_BGRA;
53 static GLenum ReadType = GL_UNSIGNED_SHORT_4_4_4_4_REV;
55 static GLenum ReadFormat = GL_RGBA;
56 static GLenum ReadType = GL_HALF_FLOAT_ARB;
57 #undef GL_OES_read_format
64 APosX = 5; APosY = 20;
65 BPosX = APosX + ImgWidth + 5; BPosY = 20;
66 CPosX = BPosX + ImgWidth + 5; CPosY = 20;
71 PrintString(const char *s)
74 glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s);
81 SetupPixelTransfer(GLboolean invert)
84 glPixelTransferf(GL_RED_SCALE, -1.0);
85 glPixelTransferf(GL_RED_BIAS, 1.0);
86 glPixelTransferf(GL_GREEN_SCALE, -1.0);
87 glPixelTransferf(GL_GREEN_BIAS, 1.0);
88 glPixelTransferf(GL_BLUE_SCALE, -1.0);
89 glPixelTransferf(GL_BLUE_BIAS, 1.0);
92 glPixelTransferf(GL_RED_SCALE, 1.0);
93 glPixelTransferf(GL_RED_BIAS, 0.0);
94 glPixelTransferf(GL_GREEN_SCALE, 1.0);
95 glPixelTransferf(GL_GREEN_BIAS, 0.0);
96 glPixelTransferf(GL_BLUE_SCALE, 1.0);
97 glPixelTransferf(GL_BLUE_BIAS, 0.0);
103 * Exercise Pixel Pack parameters by reading the image in four pieces.
106 ComplexReadPixels(GLint x, GLint y, GLsizei width, GLsizei height,
107 GLenum format, GLenum type, GLvoid *pixels)
109 const GLsizei width0 = width / 2;
110 const GLsizei width1 = width - width0;
111 const GLsizei height0 = height / 2;
112 const GLsizei height1 = height - height0;
114 glPixelStorei(GL_PACK_ROW_LENGTH, width);
116 /* lower-left quadrant */
117 glReadPixels(x, y, width0, height0, format, type, pixels);
119 /* lower-right quadrant */
120 glPixelStorei(GL_PACK_SKIP_PIXELS, width0);
121 glReadPixels(x + width0, y, width1, height0, format, type, pixels);
123 /* upper-left quadrant */
124 glPixelStorei(GL_PACK_SKIP_PIXELS, 0);
125 glPixelStorei(GL_PACK_SKIP_ROWS, height0);
126 glReadPixels(x, y + height0, width0, height1, format, type, pixels);
128 /* upper-right quadrant */
129 glPixelStorei(GL_PACK_SKIP_PIXELS, width0);
130 glPixelStorei(GL_PACK_SKIP_ROWS, height0);
131 glReadPixels(x + width0, y + height0, width1, height1, format, type, pixels);
133 /* restore defaults */
134 glPixelStorei(GL_PACK_SKIP_PIXELS, 0);
135 glPixelStorei(GL_PACK_SKIP_ROWS, 0);
136 glPixelStorei(GL_PACK_ROW_LENGTH, ImgWidth);
144 glClearColor(.3, .3, .3, 1);
145 glClear( GL_COLOR_BUFFER_BIT );
147 glRasterPos2i(5, ImgHeight+25);
148 PrintString("f = toggle front/back s = toggle scale/bias b = benchmark");
150 /* draw original image */
151 glRasterPos2i(APosX, 5);
152 PrintString("Original");
153 glRasterPos2i(APosX, APosY);
155 SetupPixelTransfer(GL_FALSE);
156 glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
157 glDrawPixels(ImgWidth, ImgHeight, ImgFormat, GL_UNSIGNED_BYTE, Image);
159 /* might try alignment=4 here for testing */
160 glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
161 glPixelStorei(GL_PACK_ALIGNMENT, 1);
163 /* do readpixels, drawpixels */
164 glRasterPos2i(BPosX, 5);
165 PrintString("Read/DrawPixels");
166 SetupPixelTransfer(ScaleAndBias);
170 GLint startTime = glutGet(GLUT_ELAPSED_TIME);
171 GLdouble seconds, pixelsPerSecond;
172 printf("Benchmarking...\n");
174 glReadPixels(APosX, APosY, ImgWidth, ImgHeight,
175 ReadFormat, ReadType, TempImage);
177 endTime = glutGet(GLUT_ELAPSED_TIME);
178 } while (endTime - startTime < 4000); /* 4 seconds */
179 seconds = (double) (endTime - startTime) / 1000.0;
180 pixelsPerSecond = reads * ImgWidth * ImgHeight / seconds;
181 printf("Result: %d reads in %f seconds = %f pixels/sec\n",
182 reads, seconds, pixelsPerSecond);
183 Benchmark = GL_FALSE;
186 /* clear the temporary image to white (helpful for debugging */
187 memset(TempImage, 255, ImgWidth * ImgHeight * 4);
189 glReadPixels(APosX, APosY, ImgWidth, ImgHeight,
190 ReadFormat, ReadType, TempImage);
191 (void) ComplexReadPixels;
193 /* you might use this when debugging */
194 ComplexReadPixels(APosX, APosY, ImgWidth, ImgHeight,
195 ReadFormat, ReadType, TempImage);
198 glRasterPos2i(BPosX, BPosY);
199 glDisable(GL_DITHER);
200 SetupPixelTransfer(GL_FALSE);
201 glDrawPixels(ImgWidth, ImgHeight, ReadFormat, ReadType, TempImage);
204 glRasterPos2i(CPosX, 5);
205 PrintString("CopyPixels");
206 glRasterPos2i(CPosX, CPosY);
207 glDisable(GL_DITHER);
208 SetupPixelTransfer(ScaleAndBias);
209 glCopyPixels(APosX, APosY, ImgWidth, ImgHeight, GL_COLOR);
219 Reshape( int width, int height )
221 glViewport( 0, 0, width, height );
222 glMatrixMode( GL_PROJECTION );
224 glOrtho( 0.0, width, 0.0, height, -1.0, 1.0 );
225 glMatrixMode( GL_MODELVIEW );
231 Key( unsigned char key, int x, int y )
240 ScaleAndBias = !ScaleAndBias;
243 DrawFront = !DrawFront;
245 glDrawBuffer(GL_FRONT);
246 glReadBuffer(GL_FRONT);
249 glDrawBuffer(GL_BACK);
250 glReadBuffer(GL_BACK);
252 printf("glDrawBuffer(%s)\n", DrawFront ? "GL_FRONT" : "GL_BACK");
263 Init( GLboolean ciMode )
265 GLboolean have_read_format = GL_FALSE;
267 printf("GL_VERSION = %s\n", (char *) glGetString(GL_VERSION));
268 printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
270 Image = LoadRGBImage( IMAGE_FILE, &ImgWidth, &ImgHeight, &ImgFormat );
272 printf("Couldn't read %s\n", IMAGE_FILE);
277 /* Convert RGB image to grayscale */
278 GLubyte *indexImage = (GLubyte *) malloc( ImgWidth * ImgHeight );
280 for (i=0; i<ImgWidth*ImgHeight; i++) {
281 int gray = Image[i*3] + Image[i*3+1] + Image[i*3+2];
282 indexImage[i] = gray / 3;
286 ImgFormat = GL_COLOR_INDEX;
288 for (i=0;i<255;i++) {
290 glutSetColor(i, g, g, g);
294 #ifdef GL_OES_read_format
295 if ( glutExtensionSupported( "GL_OES_read_format" ) ) {
296 glGetIntegerv(GL_IMPLEMENTATION_COLOR_READ_TYPE_OES, (GLint *) &ReadType);
297 glGetIntegerv(GL_IMPLEMENTATION_COLOR_READ_FORMAT_OES, (GLint *) &ReadFormat);
299 have_read_format = GL_TRUE;
303 printf( "GL_OES_read_format %ssupported. "
304 "Using type / format = 0x%04x / 0x%04x\n",
305 (have_read_format) ? "" : "not ",
306 ReadType, ReadFormat );
308 printf("Loaded %d by %d image\n", ImgWidth, ImgHeight );
310 glPixelStorei(GL_UNPACK_ROW_LENGTH, ImgWidth);
311 glPixelStorei(GL_PACK_ROW_LENGTH, ImgWidth);
315 /* allocate large TempImage to store and image data type, plus an
316 * extra 1KB in case we're tinkering with pack alignment.
318 TempImage = (GLubyte *) malloc(ImgWidth * ImgHeight * 4 * 4
325 main( int argc, char *argv[] )
327 GLboolean ciMode = GL_FALSE;
328 if (argc > 1 && strcmp(argv[1], "-ci")==0) {
331 glutInit( &argc, argv );
332 glutInitWindowPosition( 0, 0 );
333 glutInitWindowSize( 750, 250 );
335 glutInitDisplayMode( GLUT_INDEX | GLUT_DOUBLE );
337 glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE );
338 glutCreateWindow(argv[0]);
340 glutReshapeFunc( Reshape );
341 glutKeyboardFunc( Key );
342 glutDisplayFunc( Display );