copypix.c revision 32001f49 
1/**
2 * glCopyPixels test
3 *
4 * Brian Paul
5 * 14 Sep 2007
6 */
7
8
9#include <stdio.h>
10#include <stdlib.h>
11#include <string.h>
12#include <GL/glew.h>
13#include "glut_wrap.h"
14
15#include "readtex.h"
16
17#define IMAGE_FILE DEMOS_DATA_DIR "arch.rgb"
18
19static int ImgWidth, ImgHeight;
20static GLenum ImgFormat;
21static GLubyte *Image = NULL;
22
23static int WinWidth = 800, WinHeight = 800;
24static int Xpos, Ypos;
25static int Scissor = 0;
26static float Xzoom, Yzoom;
27static GLboolean DrawFront = GL_FALSE;
28static GLboolean Dither = GL_TRUE;
29static GLboolean Invert = GL_FALSE;
30
31
32static void Reset( void )
33{
34   Xpos = Ypos = 20;
35   Scissor = 0;
36   Xzoom = Yzoom = 1.0;
37}
38
39
40static void Display( void )
41{
42   const int dx = (WinWidth - ImgWidth) / 2;
43   const int dy = (WinHeight - ImgHeight) / 2;
44
45   if (DrawFront) {
46      glDrawBuffer(GL_FRONT);
47      glReadBuffer(GL_FRONT);
48   }
49   else {
50      glDrawBuffer(GL_BACK);
51      glReadBuffer(GL_BACK);
52   }
53
54   glClear( GL_COLOR_BUFFER_BIT );
55
56   /* draw original image */
57   glWindowPos2iARB(dx, dy);
58   glDrawPixels(ImgWidth, ImgHeight, ImgFormat, GL_UNSIGNED_BYTE, Image);
59
60   if (Scissor)
61      glEnable(GL_SCISSOR_TEST);
62
63   if (Invert) {
64      glPixelTransferf(GL_RED_SCALE, -1.0);
65      glPixelTransferf(GL_GREEN_SCALE, -1.0);
66      glPixelTransferf(GL_BLUE_SCALE, -1.0);
67      glPixelTransferf(GL_RED_BIAS, 1.0);
68      glPixelTransferf(GL_GREEN_BIAS, 1.0);
69      glPixelTransferf(GL_BLUE_BIAS, 1.0);
70   }
71
72   /* draw copy */
73   glPixelZoom(Xzoom, Yzoom);
74   glWindowPos2iARB(Xpos, Ypos);
75   glCopyPixels(dx, dy, ImgWidth, ImgHeight, GL_COLOR);
76   glPixelZoom(1, 1);
77
78   glDisable(GL_SCISSOR_TEST);
79
80   if (Invert) {
81      glPixelTransferf(GL_RED_SCALE, 1.0);
82      glPixelTransferf(GL_GREEN_SCALE, 1.0);
83      glPixelTransferf(GL_BLUE_SCALE, 1.0);
84      glPixelTransferf(GL_RED_BIAS, 0.0);
85      glPixelTransferf(GL_GREEN_BIAS, 0.0);
86      glPixelTransferf(GL_BLUE_BIAS, 0.0);
87   }
88
89   if (DrawFront)
90      glFinish();
91   else
92      glutSwapBuffers();
93}
94
95
96static void Reshape( int width, int height )
97{
98   WinWidth = width;
99   WinHeight = height;
100
101   glViewport( 0, 0, width, height );
102   glMatrixMode( GL_PROJECTION );
103   glLoadIdentity();
104   glOrtho( 0.0, width, 0.0, height, 0.0, 2.0 );
105   glMatrixMode( GL_MODELVIEW );
106   glLoadIdentity();
107
108   glScissor(width/4, height/4, width/2, height/2);
109}
110
111
112static void Key( unsigned char key, int x, int y )
113{
114   (void) x;
115   (void) y;
116   switch (key) {
117      case ' ':
118         Reset();
119         break;
120      case 'd':
121         Dither = !Dither;
122         if (Dither)
123            glEnable(GL_DITHER);
124         else
125            glDisable(GL_DITHER);
126         break;
127      case 'i':
128         Invert = !Invert;
129         break;
130      case 's':
131         Scissor = !Scissor;
132         break;
133      case 'x':
134         Xzoom -= 0.1;
135         break;
136      case 'X':
137         Xzoom += 0.1;
138         break;
139      case 'y':
140         Yzoom -= 0.1;
141         break;
142      case 'Y':
143         Yzoom += 0.1;
144         break;
145      case 'f':
146         DrawFront = !DrawFront;
147         printf("glDrawBuffer(%s)\n", DrawFront ? "GL_FRONT" : "GL_BACK");
148         break;
149      case 27:
150         exit(0);
151         break;
152   }
153   glutPostRedisplay();
154}
155
156
157static void SpecialKey( int key, int x, int y )
158{
159   const int step = (glutGetModifiers() & GLUT_ACTIVE_SHIFT) ? 10 : 1;
160   (void) x;
161   (void) y;
162   switch (key) {
163      case GLUT_KEY_UP:
164         Ypos += step;
165         break;
166      case GLUT_KEY_DOWN:
167         Ypos -= step;
168         break;
169      case GLUT_KEY_LEFT:
170         Xpos -= step;
171         break;
172      case GLUT_KEY_RIGHT:
173         Xpos += step;
174         break;
175   }
176   glutPostRedisplay();
177}
178
179
180static void Init( GLboolean ciMode, const char *filename )
181{
182   printf("GL_VERSION = %s\n", (char *) glGetString(GL_VERSION));
183   printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
184
185   Image = LoadRGBImage( filename, &ImgWidth, &ImgHeight, &ImgFormat );
186   if (!Image) {
187      printf("Couldn't read %s\n", filename);
188      exit(0);
189   }
190
191   if (ciMode) {
192      /* Convert RGB image to grayscale */
193      GLubyte *indexImage = (GLubyte *) malloc( ImgWidth * ImgHeight );
194      GLint i;
195      for (i=0; i<ImgWidth*ImgHeight; i++) {
196         int gray = Image[i*3] + Image[i*3+1] + Image[i*3+2];
197         indexImage[i] = gray / 3;
198      }
199      free(Image);
200      Image = indexImage;
201      ImgFormat = GL_COLOR_INDEX;
202
203      for (i=0;i<255;i++) {
204         float g = i / 255.0;
205         glutSetColor(i, g, g, g);
206      }
207   }
208
209   printf("Loaded %d by %d image\n", ImgWidth, ImgHeight );
210
211   glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
212   glPixelStorei(GL_UNPACK_ROW_LENGTH, ImgWidth);
213
214   Reset();
215}
216
217
218static void Usage(void)
219{
220   printf("Keys:\n");
221   printf("       SPACE  Reset Parameters\n");
222   printf("     Up/Down  Move image up/down (SHIFT for large step)\n");
223   printf("  Left/Right  Move image left/right (SHIFT for large step)\n");
224   printf("           x  Decrease X-axis PixelZoom\n");
225   printf("           X  Increase X-axis PixelZoom\n");
226   printf("           y  Decrease Y-axis PixelZoom\n");
227   printf("           Y  Increase Y-axis PixelZoom\n");
228   printf("           s  Toggle GL_SCISSOR_TEST\n");
229   printf("           f  Toggle front/back buffer drawing\n");
230   printf("         ESC  Exit\n");
231}
232
233
234int main( int argc, char *argv[] )
235{
236   GLboolean ciMode = GL_FALSE;
237   const char *filename = IMAGE_FILE;
238   int i = 1;
239
240   glutInitWindowSize( WinWidth, WinHeight );
241   glutInit( &argc, argv );
242
243   if (argc > i && strcmp(argv[i], "-ci")==0) {
244      ciMode = GL_TRUE;
245      i++;
246   }
247   if (argc > i) {
248      filename = argv[i];
249   }
250
251   if (ciMode)
252      glutInitDisplayMode( GLUT_INDEX | GLUT_DOUBLE );
253   else
254      glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE);
255
256   glutCreateWindow(argv[0]);
257   glewInit();
258
259   Init(ciMode, filename);
260   Usage();
261
262   glutReshapeFunc( Reshape );
263   glutKeyboardFunc( Key );
264   glutSpecialFunc( SpecialKey );
265   glutDisplayFunc( Display );
266
267   glutMainLoop();
268   return 0;
269}
270