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progs/samples: improve copy.c demo

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If the test image was larger than the window, nothing was drawn because
of invalid raster position.  Use glWindowPos instead of glRasterPos.
Also, use integer src/dst coordinates to avoid grabbing black pixels
outside of the src image region.
This commit is contained in:
Brian Paul 2010-03-17 10:17:04 -06:00
parent ef92fe85de
commit a196a5d330
1 changed files with 14 additions and 13 deletions
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27
progs/samples/copy.c
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@ -25,6 +25,7 @@
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <GL/glew.h>
#include <GL/glut.h>
@ -35,7 +36,6 @@ GLint windW, windH;
char *fileName = 0;
PPMImage *image;
float point[3];
float zoom;
GLint x, y;
@ -97,27 +97,27 @@ static void Mouse(int button, int state, int mouseX, int mouseY)
static void Draw(void)
{
GLint src[3], dst[3];
glClear(GL_COLOR_BUFFER_BIT);
point[0] = (windW / 2) - (image->sizeX / 2);
point[1] = (windH / 2) - (image->sizeY / 2);
point[2] = 0;
glRasterPos3fv(point);
src[0] = (int) ((windW / 2.0) - (image->sizeX / 2.0));
src[1] = (int) ((windH / 2.0) - (image->sizeY / 2.0));
src[2] = 0;
glWindowPos3ivARB(src);
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glPixelZoom(1.0, 1.0);
glDrawPixels(image->sizeX, image->sizeY, GL_RGB, GL_UNSIGNED_BYTE,
image->data);
point[0] = (float)x;
point[1] = windH - (float)y;
point[2] = 0.0;
glRasterPos3fv(point);
dst[0] = x;
dst[1] = windH - y;
dst[2] = 0;
glWindowPos3ivARB(dst);
glPixelZoom(zoom, zoom);
glCopyPixels((windW/2)-(image->sizeX/2),
(windH/2)-(image->sizeY/2),
glCopyPixels(src[0], src[1],
image->sizeX, image->sizeY, GL_COLOR);
glFlush();
@ -170,8 +170,8 @@ int main(int argc, char **argv)
image = LoadPPM(fileName);
windW = 300;
windH = 300;
windW = 2*300;
windH = 2*300;
glutInitWindowPosition(0, 0); glutInitWindowSize( windW, windH);
type = GLUT_RGB;
@ -182,6 +182,7 @@ int main(int argc, char **argv)
exit(1);
}
glewInit();
Init();
glutReshapeFunc(Reshape);