Hi All,
Alex Reche <[EMAIL PROTECTED]> submitted this directly to me, but because I'm
not finished doing the Win32 build subdirectory updates I haven't yet checked
it for validity with the current code base, so I thought I'd pass it onto the
proper list to make sure it didn't fall through the cracks if it hadn't yet
been dealth with.
PS: I have not checked my OpenGL ref's to make sure I know what the "proper"
behavior is either, should there be any spec'd.
-Ted
--cut here for original message---
Hello, my name is Alex, and I'm a spanish student in France. I'm
making a project that uses Mesa and I think that a found a bug.
When I try to make two windows and copy the image of one to the
other, with glReadPixels and glDrawPixels y have the image reversed...
I use Windows NT and the version 3.0 of Mesa.
With this code you have the error:
======================================
#include <GL/glut.h>
char image[4*256*256];
void glReadPixelsDisplayFunc(void) {
glClearColor(0.0, 0.0, 0.0, 0.0);
glClear (GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
glColor3f (1.0, 1.0, 1.0);
glEnable(GL_LINE_STIPPLE);
glBegin(GL_LINE_STRIP);
glVertex3f(0.5,0.5,0.5);
glVertex3f(-0.5,-0.5,-0.5);
glEnd();
glFlush();
glReadPixels(0,0,256,256,GL_RGBA, GL_UNSIGNED_BYTE,image);
glutSwapBuffers();
}
void glDrawPixelsDisplayFunc(void) {
glDrawPixels(256,256,GL_RGBA, GL_UNSIGNED_BYTE,image);
glutSwapBuffers();
}
void ReshapeFunc(int w, int h) {
w;h;
glutReshapeWindow(256,256);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluOrtho2D(-1, 1, -1, 1);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glViewport(0,0,256,256);
}
int main(int argc, char **argv) {
glutInit(&argc, argv);
glutInitWindowPosition(256,256);
glutInitWindowSize(256,256);
glutInitDisplayMode(GLUT_RGBA | GLUT_DEPTH | GLUT_DOUBLE);
// Window for glReadPixels
glutCreateWindow("glReadPixels");
glutDisplayFunc(glReadPixelsDisplayFunc);
glutReshapeFunc(ReshapeFunc);
glutInitWindowPosition(520,256);
// Window for glDrawPixels
glutCreateWindow("glDrawPixels");
glutDisplayFunc(glDrawPixelsDisplayFunc);
glutReshapeFunc(ReshapeFunc);
glutMainLoop();
}
==============================================
To fix the error I have modify one line in the wmesa.c file.
In the line 1074 I have change:
Color = GetPixel(DC, x+i, y);
by:
Color = GetPixel(DC, x+i, ctx->Buffer->Height - y - 1);
I don't know if this is the solution, but is the only that I can find...
Please, say me how to solve this error or if my solution if good.
Thanks
Alex.
