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| -rw-r--r-- | progs/demos/readpix.c | 253 |
1 files changed, 253 insertions, 0 deletions
diff --git a/progs/demos/readpix.c b/progs/demos/readpix.c new file mode 100644 index 0000000..b6b0675 --- /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; +} |