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-rw-r--r--progs/demos/readpix.c253
1 files changed, 253 insertions, 0 deletions
diff --git a/progs/demos/readpix.c b/progs/demos/readpix.c
new file mode 100644
index 00000000000..b6b067502d5
--- /dev/null
+++ b/progs/demos/readpix.c
@@ -0,0 +1,253 @@
+/* $Id: readpix.c,v 1.1 2000/03/01 16:23:14 brianp Exp $ */
+
+/*
+ * glReadPixels and glCopyPixels test
+ *
+ * Brian Paul March 1, 2000 This file is in the public domain.
+ */
+
+/*
+ * $Log: readpix.c,v $
+ * Revision 1.1 2000/03/01 16:23:14 brianp
+ * test glDraw/Read/CopyPixels()
+ *
+ */
+
+
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include <GL/glut.h>
+
+#include "../util/readtex.c" /* a hack, I know */
+
+#define IMAGE_FILE "../images/girl.rgb"
+
+static int ImgWidth, ImgHeight;
+static GLenum ImgFormat;
+static GLubyte *Image = NULL;
+
+static int APosX, APosY; /* simple drawpixels */
+static int BPosX, BPosY; /* read/draw pixels */
+static int CPosX, CPosY; /* copypixels */
+
+static GLboolean DrawFront = GL_FALSE;
+static GLboolean ScaleAndBias = GL_FALSE;
+
+static GLubyte *TempImage = NULL;
+
+
+static void
+Reset( void )
+{
+ APosX = 5; APosY = 20;
+ BPosX = APosX + ImgWidth + 5; BPosY = 20;
+ CPosX = BPosX + ImgWidth + 5; CPosY = 20;
+}
+
+
+static void
+PrintString(const char *s)
+{
+ while (*s) {
+ glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s);
+ s++;
+ }
+}
+
+
+static void
+SetupPixelTransfer(GLboolean invert)
+{
+ if (invert) {
+ glPixelTransferf(GL_RED_SCALE, -1.0);
+ glPixelTransferf(GL_RED_BIAS, 1.0);
+ glPixelTransferf(GL_GREEN_SCALE, -1.0);
+ glPixelTransferf(GL_GREEN_BIAS, 1.0);
+ glPixelTransferf(GL_BLUE_SCALE, -1.0);
+ glPixelTransferf(GL_BLUE_BIAS, 1.0);
+ }
+ else {
+ glPixelTransferf(GL_RED_SCALE, 1.0);
+ glPixelTransferf(GL_RED_BIAS, 0.0);
+ glPixelTransferf(GL_GREEN_SCALE, 1.0);
+ glPixelTransferf(GL_GREEN_BIAS, 0.0);
+ glPixelTransferf(GL_BLUE_SCALE, 1.0);
+ glPixelTransferf(GL_BLUE_BIAS, 0.0);
+ }
+}
+
+
+static void
+Display( void )
+{
+ glClear( GL_COLOR_BUFFER_BIT );
+
+ glRasterPos2i(5, ImgHeight+25);
+ PrintString("f = toggle front/back b = toggle scale/bias");
+
+ /* draw original image */
+ glRasterPos2i(APosX, 5);
+ PrintString("Original");
+ glRasterPos2i(APosX, APosY);
+ glEnable(GL_DITHER);
+ SetupPixelTransfer(GL_FALSE);
+ glDrawPixels(ImgWidth, ImgHeight, ImgFormat, GL_UNSIGNED_BYTE, Image);
+
+ /* do readpixels, drawpixels */
+ glRasterPos2i(BPosX, 5);
+ PrintString("Read/DrawPixels");
+ SetupPixelTransfer(ScaleAndBias);
+ glReadPixels(APosX, APosY, ImgWidth, ImgHeight,
+ ImgFormat, GL_UNSIGNED_BYTE, TempImage);
+ glRasterPos2i(BPosX, BPosY);
+ glDisable(GL_DITHER);
+ SetupPixelTransfer(GL_FALSE);
+ glDrawPixels(ImgWidth, ImgHeight, ImgFormat, GL_UNSIGNED_BYTE, TempImage);
+
+ /* do copypixels */
+ glRasterPos2i(CPosX, 5);
+ PrintString("CopyPixels");
+ glRasterPos2i(CPosX, CPosY);
+ glDisable(GL_DITHER);
+ SetupPixelTransfer(ScaleAndBias);
+ glCopyPixels(APosX, APosY, ImgWidth, ImgHeight, GL_COLOR);
+
+ if (!DrawFront)
+ glutSwapBuffers();
+}
+
+
+static void Reshape( int width, int height )
+{
+ glViewport( 0, 0, width, height );
+ glMatrixMode( GL_PROJECTION );
+ glLoadIdentity();
+ glOrtho( 0.0, width, 0.0, height, -1.0, 1.0 );
+ glMatrixMode( GL_MODELVIEW );
+ glLoadIdentity();
+}
+
+
+static void Key( unsigned char key, int x, int y )
+{
+ (void) x;
+ (void) y;
+ switch (key) {
+ case 'b':
+ ScaleAndBias = !ScaleAndBias;
+ break;
+ case 'f':
+ DrawFront = !DrawFront;
+ if (DrawFront)
+ glDrawBuffer(GL_FRONT);
+ else
+ glDrawBuffer(GL_BACK);
+ 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 )
+{
+ (void) x;
+ (void) y;
+#if 0
+ switch (key) {
+ case GLUT_KEY_UP:
+ Ypos += 1;
+ break;
+ case GLUT_KEY_DOWN:
+ Ypos -= 1;
+ break;
+ case GLUT_KEY_LEFT:
+ Xpos -= 1;
+ break;
+ case GLUT_KEY_RIGHT:
+ Xpos += 1;
+ break;
+ }
+#endif
+ glutPostRedisplay();
+}
+
+
+static void
+Init( GLboolean ciMode )
+{
+ printf("GL_VERSION = %s\n", (char *) glGetString(GL_VERSION));
+ printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
+
+ Image = LoadRGBImage( IMAGE_FILE, &ImgWidth, &ImgHeight, &ImgFormat );
+ if (!Image) {
+ printf("Couldn't read %s\n", IMAGE_FILE);
+ exit(0);
+ }
+
+ if (ciMode) {
+ /* Convert RGB image to grayscale */
+ GLubyte *indexImage = 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);
+ glPixelStorei(GL_PACK_ALIGNMENT, 1);
+ glPixelStorei(GL_PACK_ROW_LENGTH, ImgWidth);
+
+ Reset();
+
+ TempImage = (GLubyte *) malloc(ImgWidth * ImgHeight * 4 * sizeof(GLubyte));
+ assert(TempImage);
+}
+
+
+int main( int argc, char *argv[] )
+{
+ GLboolean ciMode = GL_FALSE;
+
+ if (argc > 1 && strcmp(argv[1], "-ci")==0) {
+ ciMode = GL_TRUE;
+ }
+
+ glutInit( &argc, argv );
+ glutInitWindowPosition( 0, 0 );
+ glutInitWindowSize( 750, 250 );
+
+ if (ciMode)
+ glutInitDisplayMode( GLUT_INDEX | GLUT_DOUBLE );
+ else
+ glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE );
+
+ glutCreateWindow(argv[0]);
+
+ Init(ciMode);
+
+ glutReshapeFunc( Reshape );
+ glutKeyboardFunc( Key );
+ glutSpecialFunc( SpecialKey );
+ glutDisplayFunc( Display );
+
+ glutMainLoop();
+ return 0;
+}