--- /dev/null
+/**
+ * glCopyPixels test
+ *
+ * Brian Paul
+ * 14 Sep 2007
+ */
+
+
+#define GL_GLEXT_PROTOTYPES
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <GL/glut.h>
+
+#include "readtex.h"
+
+#define IMAGE_FILE "../images/arch.rgb"
+
+static int ImgWidth, ImgHeight;
+static GLenum ImgFormat;
+static GLubyte *Image = NULL;
+
+static int WinWidth = 800, WinHeight = 800;
+static int Xpos, Ypos;
+static int Scissor = 0;
+static float Xzoom, Yzoom;
+static GLboolean DrawFront = GL_FALSE;
+static GLboolean Dither = GL_TRUE;
+
+
+static void Reset( void )
+{
+ Xpos = Ypos = 20;
+ Scissor = 0;
+ Xzoom = Yzoom = 1.0;
+}
+
+
+static void Display( void )
+{
+ const int dx = (WinWidth - ImgWidth) / 2;
+ const int dy = (WinHeight - ImgHeight) / 2;
+
+ if (DrawFront) {
+ glDrawBuffer(GL_FRONT);
+ glReadBuffer(GL_FRONT);
+ }
+ else {
+ glDrawBuffer(GL_BACK);
+ glReadBuffer(GL_BACK);
+ }
+
+ glClear( GL_COLOR_BUFFER_BIT );
+
+ /* draw original image */
+ glWindowPos2iARB(dx, dy);
+ glDrawPixels(ImgWidth, ImgHeight, ImgFormat, GL_UNSIGNED_BYTE, Image);
+
+ if (Scissor)
+ glEnable(GL_SCISSOR_TEST);
+
+ /* draw copy */
+ glPixelZoom(Xzoom, Yzoom);
+ glWindowPos2iARB(Xpos, Ypos);
+ glCopyPixels(dx, dy, ImgWidth, ImgHeight, GL_COLOR);
+ glPixelZoom(1, 1);
+
+ glDisable(GL_SCISSOR_TEST);
+
+ if (DrawFront)
+ glFinish();
+ else
+ glutSwapBuffers();
+}
+
+
+static void Reshape( int width, int height )
+{
+ WinWidth = width;
+ WinHeight = height;
+
+ glViewport( 0, 0, width, height );
+ glMatrixMode( GL_PROJECTION );
+ glLoadIdentity();
+ glOrtho( 0.0, width, 0.0, height, 0.0, 2.0 );
+ glMatrixMode( GL_MODELVIEW );
+ glLoadIdentity();
+
+ glScissor(width/4, height/4, width/2, height/2);
+}
+
+
+static void Key( unsigned char key, int x, int y )
+{
+ (void) x;
+ (void) y;
+ switch (key) {
+ case ' ':
+ Reset();
+ break;
+ case 'd':
+ Dither = !Dither;
+ if (Dither)
+ glEnable(GL_DITHER);
+ else
+ glDisable(GL_DITHER);
+ break;
+ case 's':
+ Scissor = !Scissor;
+ break;
+ case 'x':
+ Xzoom -= 0.1;
+ break;
+ case 'X':
+ Xzoom += 0.1;
+ break;
+ case 'y':
+ Yzoom -= 0.1;
+ break;
+ case 'Y':
+ Yzoom += 0.1;
+ break;
+ case 'f':
+ DrawFront = !DrawFront;
+ printf("glDrawBuffer(%s)\n", DrawFront ? "GL_FRONT" : "GL_BACK");
+ break;
+ case 27:
+ exit(0);
+ break;
+ }
+ glutPostRedisplay();
+}
+
+
+static void SpecialKey( int key, int x, int y )
+{
+ const int step = (glutGetModifiers() & GLUT_ACTIVE_SHIFT) ? 10 : 1;
+ (void) x;
+ (void) y;
+ switch (key) {
+ case GLUT_KEY_UP:
+ Ypos += step;
+ break;
+ case GLUT_KEY_DOWN:
+ Ypos -= step;
+ break;
+ case GLUT_KEY_LEFT:
+ Xpos -= step;
+ break;
+ case GLUT_KEY_RIGHT:
+ Xpos += step;
+ break;
+ }
+ glutPostRedisplay();
+}
+
+
+static void Init( GLboolean ciMode, const char *filename )
+{
+ printf("GL_VERSION = %s\n", (char *) glGetString(GL_VERSION));
+ printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
+
+ Image = LoadRGBImage( filename, &ImgWidth, &ImgHeight, &ImgFormat );
+ if (!Image) {
+ printf("Couldn't read %s\n", filename);
+ exit(0);
+ }
+
+ if (ciMode) {
+ /* Convert RGB image to grayscale */
+ GLubyte *indexImage = (GLubyte *) malloc( ImgWidth * ImgHeight );
+ GLint i;
+ for (i=0; i<ImgWidth*ImgHeight; i++) {
+ int gray = Image[i*3] + Image[i*3+1] + Image[i*3+2];
+ indexImage[i] = gray / 3;
+ }
+ free(Image);
+ Image = indexImage;
+ ImgFormat = GL_COLOR_INDEX;
+
+ for (i=0;i<255;i++) {
+ float g = i / 255.0;
+ glutSetColor(i, g, g, g);
+ }
+ }
+
+ printf("Loaded %d by %d image\n", ImgWidth, ImgHeight );
+
+ glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+ glPixelStorei(GL_UNPACK_ROW_LENGTH, ImgWidth);
+
+ Reset();
+}
+
+
+static void Usage(void)
+{
+ printf("Keys:\n");
+ printf(" SPACE Reset Parameters\n");
+ printf(" Up/Down Move image up/down (SHIFT for large step)\n");
+ printf(" Left/Right Move image left/right (SHIFT for large step)\n");
+ printf(" x Decrease X-axis PixelZoom\n");
+ printf(" X Increase X-axis PixelZoom\n");
+ printf(" y Decrease Y-axis PixelZoom\n");
+ printf(" Y Increase Y-axis PixelZoom\n");
+ printf(" s Toggle GL_SCISSOR_TEST\n");
+ printf(" f Toggle front/back buffer drawing\n");
+ printf(" ESC Exit\n");
+}
+
+
+int main( int argc, char *argv[] )
+{
+ GLboolean ciMode = GL_FALSE;
+ const char *filename = IMAGE_FILE;
+ int i = 1;
+
+ if (argc > i && strcmp(argv[i], "-ci")==0) {
+ ciMode = GL_TRUE;
+ i++;
+ }
+ if (argc > i) {
+ filename = argv[i];
+ }
+
+ glutInit( &argc, argv );
+ glutInitWindowPosition( 0, 0 );
+ glutInitWindowSize( WinWidth, WinHeight );
+
+ if (ciMode)
+ glutInitDisplayMode( GLUT_INDEX | GLUT_DOUBLE );
+ else
+ glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE);
+
+ glutCreateWindow(argv[0]);
+
+ Init(ciMode, filename);
+ Usage();
+
+ glutReshapeFunc( Reshape );
+ glutKeyboardFunc( Key );
+ glutSpecialFunc( SpecialKey );
+ glutDisplayFunc( Display );
+
+ glutMainLoop();
+ return 0;
+}