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;
33 #define ReadFormat ImgFormat
34 #define ReadType GL_UNSIGNED_BYTE
37 static GLenum ReadFormat = GL_RGBA;
38 static GLenum ReadType = GL_UNSIGNED_BYTE;
41 static GLenum ReadFormat = GL_RGB;
42 static GLenum ReadType = GL_UNSIGNED_SHORT_5_6_5;
45 static GLenum ReadFormat = GL_RGBA;
46 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;
53 static GLenum ReadFormat = GL_BGRA;
54 static GLenum ReadType = GL_UNSIGNED_SHORT_4_4_4_4_REV;
61 APosX = 5; APosY = 20;
62 BPosX = APosX + ImgWidth + 5; BPosY = 20;
63 CPosX = BPosX + ImgWidth + 5; CPosY = 20;
68 PrintString(const char *s)
71 glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s);
78 SetupPixelTransfer(GLboolean 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);
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);
102 glClearColor(.3, .3, .3, 1);
103 glClear( GL_COLOR_BUFFER_BIT );
105 glRasterPos2i(5, ImgHeight+25);
106 PrintString("f = toggle front/back s = toggle scale/bias b = benchmark");
108 /* draw original image */
109 glRasterPos2i(APosX, 5);
110 PrintString("Original");
111 glRasterPos2i(APosX, APosY);
113 SetupPixelTransfer(GL_FALSE);
114 glDrawPixels(ImgWidth, ImgHeight, ImgFormat, GL_UNSIGNED_BYTE, Image);
116 /* do readpixels, drawpixels */
117 glRasterPos2i(BPosX, 5);
118 PrintString("Read/DrawPixels");
119 SetupPixelTransfer(ScaleAndBias);
123 GLint startTime = glutGet(GLUT_ELAPSED_TIME);
124 GLdouble seconds, pixelsPerSecond;
125 printf("Benchmarking...\n");
127 glReadPixels(APosX, APosY, ImgWidth, ImgHeight,
128 ReadFormat, ReadType, TempImage);
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;
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);
144 glRasterPos2i(BPosX, BPosY);
145 glDisable(GL_DITHER);
146 SetupPixelTransfer(GL_FALSE);
147 glDrawPixels(ImgWidth, ImgHeight, ReadFormat, ReadType, TempImage);
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);
165 Reshape( int width, int height )
167 glViewport( 0, 0, width, height );
168 glMatrixMode( GL_PROJECTION );
170 glOrtho( 0.0, width, 0.0, height, -1.0, 1.0 );
171 glMatrixMode( GL_MODELVIEW );
177 Key( unsigned char key, int x, int y )
186 ScaleAndBias = !ScaleAndBias;
189 DrawFront = !DrawFront;
191 glDrawBuffer(GL_FRONT);
192 glReadBuffer(GL_FRONT);
195 glDrawBuffer(GL_BACK);
196 glReadBuffer(GL_BACK);
198 printf("glDrawBuffer(%s)\n", DrawFront ? "GL_FRONT" : "GL_BACK");
209 Init( GLboolean ciMode )
211 GLboolean have_read_format = GL_FALSE;
213 printf("GL_VERSION = %s\n", (char *) glGetString(GL_VERSION));
214 printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
216 Image = LoadRGBImage( IMAGE_FILE, &ImgWidth, &ImgHeight, &ImgFormat );
218 printf("Couldn't read %s\n", IMAGE_FILE);
223 /* Convert RGB image to grayscale */
224 GLubyte *indexImage = (GLubyte *) malloc( ImgWidth * ImgHeight );
226 for (i=0; i<ImgWidth*ImgHeight; i++) {
227 int gray = Image[i*3] + Image[i*3+1] + Image[i*3+2];
228 indexImage[i] = gray / 3;
232 ImgFormat = GL_COLOR_INDEX;
234 for (i=0;i<255;i++) {
236 glutSetColor(i, g, g, g);
240 #ifdef GL_OES_read_format
241 if ( glutExtensionSupported( "GL_OES_read_format" ) ) {
242 glGetIntegerv(GL_IMPLEMENTATION_COLOR_READ_TYPE_OES, (GLint *) &ReadType);
243 glGetIntegerv(GL_IMPLEMENTATION_COLOR_READ_FORMAT_OES, (GLint *) &ReadFormat);
245 have_read_format = GL_TRUE;
249 printf( "GL_OES_read_format %ssupported. "
250 "Using type / format = 0x%04x / 0x%04x\n",
251 (have_read_format) ? "" : "not ",
252 ReadType, ReadFormat );
254 printf("Loaded %d by %d image\n", ImgWidth, ImgHeight );
256 glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
257 glPixelStorei(GL_UNPACK_ROW_LENGTH, ImgWidth);
258 glPixelStorei(GL_PACK_ALIGNMENT, 1);
259 glPixelStorei(GL_PACK_ROW_LENGTH, ImgWidth);
263 TempImage = (GLubyte *) malloc(ImgWidth * ImgHeight * 4 * sizeof(GLubyte));
269 main( int argc, char *argv[] )
271 GLboolean ciMode = GL_FALSE;
272 if (argc > 1 && strcmp(argv[1], "-ci")==0) {
275 glutInit( &argc, argv );
276 glutInitWindowPosition( 0, 0 );
277 glutInitWindowSize( 750, 250 );
279 glutInitDisplayMode( GLUT_INDEX | GLUT_DOUBLE );
281 glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE );
282 glutCreateWindow(argv[0]);
284 glutReshapeFunc( Reshape );
285 glutKeyboardFunc( Key );
286 glutDisplayFunc( Display );