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/* $Id: readpix.c,v 1.7 2002/05/02 09:17:59 alanh Exp $ */
/*
* glReadPixels and glCopyPixels test
*
* Brian Paul March 1, 2000 This file is in the public domain.
*/
#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 GLboolean Benchmark = GL_FALSE;
static GLubyte *TempImage = NULL;
#if 0
#define ReadFormat ImgFormat
#define ReadType GL_UNSIGNED_BYTE
#endif
#if 1
static GLenum ReadFormat = GL_RGBA;
static GLenum ReadType = GL_UNSIGNED_BYTE;
#endif
#if 0
static GLenum ReadFormat = GL_RGB;
static GLenum ReadType = GL_UNSIGNED_SHORT_5_6_5;
#endif
#if 0
static GLenum ReadFormat = GL_RGBA;
static GLenum ReadType = GL_UNSIGNED_SHORT_1_5_5_5_REV;
#endif
#if 0
static GLenum ReadFormat = GL_BGRA;
static GLenum ReadType = GL_UNSIGNED_SHORT_5_5_5_1;
#endif
#if 0
static GLenum ReadFormat = GL_BGRA;
static GLenum ReadType = GL_UNSIGNED_SHORT_4_4_4_4_REV;
#endif
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 )
{
glClearColor(.3, .3, .3, 1);
glClear( GL_COLOR_BUFFER_BIT );
glRasterPos2i(5, ImgHeight+25);
PrintString("f = toggle front/back s = toggle scale/bias b = benchmark");
/* 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);
if (Benchmark) {
GLint reads = 0;
GLint endTime;
GLint startTime = glutGet(GLUT_ELAPSED_TIME);
GLdouble seconds, pixelsPerSecond;
printf("Benchmarking...\n");
do {
glReadPixels(APosX, APosY, ImgWidth, ImgHeight,
ReadFormat, ReadType, TempImage);
reads++;
endTime = glutGet(GLUT_ELAPSED_TIME);
} while (endTime - startTime < 4000); /* 4 seconds */
seconds = (double) (endTime - startTime) / 1000.0;
pixelsPerSecond = reads * ImgWidth * ImgHeight / seconds;
printf("Result: %d reads in %f seconds = %f pixels/sec\n",
reads, seconds, pixelsPerSecond);
Benchmark = GL_FALSE;
}
else {
/* clear the temporary image to white (helpful for debugging */
memset(TempImage, 255, ImgWidth * ImgHeight * 4);
glReadPixels(APosX, APosY, ImgWidth, ImgHeight,
ReadFormat, ReadType, TempImage);
}
glRasterPos2i(BPosX, BPosY);
glDisable(GL_DITHER);
SetupPixelTransfer(GL_FALSE);
glDrawPixels(ImgWidth, ImgHeight, ReadFormat, ReadType, 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();
else
glFinish();
}
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':
Benchmark = GL_TRUE;
break;
case 's':
ScaleAndBias = !ScaleAndBias;
break;
case 'f':
DrawFront = !DrawFront;
if (DrawFront) {
glDrawBuffer(GL_FRONT);
glReadBuffer(GL_FRONT);
}
else {
glDrawBuffer(GL_BACK);
glReadBuffer(GL_BACK);
}
printf("glDrawBuffer(%s)\n", DrawFront ? "GL_FRONT" : "GL_BACK");
break;
case 27:
exit(0);
break;
}
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 );
glutDisplayFunc( Display );
glutMainLoop();
return 0;
}
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