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gluUnProject and gluPerspective
Author
I found a code for transform viewport coordinates in opengl coordinates (article 13 by Luke Benstead on nehe site), this code works really well but only if i disable the perspective.
this is the code :
float GetOGLPos(int x,int y,float*Vecteur)
{
GLint viewport[4];
GLdouble modelview[16];
GLdouble projection[16];
GLfloat winX, winY, winZ;
GLdouble posX, posY, posZ;
glGetDoublev( GL_MODELVIEW_MATRIX, modelview );
glGetDoublev( GL_PROJECTION_MATRIX, projection );
glGetIntegerv( GL_VIEWPORT, viewport );
winX = (float)x;
winY = (float)viewport[3] -(float)y;
glReadPixels( x, int(winY), 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &winZ );
gluUnProject( winX, winY, winZ, modelview, projection, viewport, &posX, &posY, &posZ);
return Vecteur[0]=posX,Vecteur[1]=posY,Vecteur[2]=posZ;
}
If you know how put the perspective in this code (or maybe i use it wrong) help me please.
MProg_25
Yes , this code is very popular , my looks like this:
I dont know what do you mean by perspective, do you mean ortho view??
Anyways , i use this code for ray casting , my origin is my camera point, and my direction is caculated:
If you use ortho projection, i dont understand why do you bother by calculating with OGLPos ?!
Vector3D GetOGLPos(int x, int y){ GLint viewport[4]; GLdouble modelview[16]; GLdouble projection[16]; GLint winX, winY; GLfloat winZ; GLdouble posX, posY, posZ; glGetDoublev( GL_MODELVIEW_MATRIX, modelview ); glGetDoublev( GL_PROJECTION_MATRIX, projection ); glGetIntegerv( GL_VIEWPORT, viewport ); winX = x; winY = viewport[3] - y; glReadPixels( winX,winY, 1,1, GL_DEPTH_COMPONENT, GL_FLOAT, &winZ ); gluUnProject( winX, winY, winZ, modelview, projection, viewport, &posX, &posY, &posZ); return Vector3D((float)posX, (float)posY, (float)posZ);}I dont know what do you mean by perspective, do you mean ortho view??
Anyways , i use this code for ray casting , my origin is my camera point, and my direction is caculated:
Vector3D vDir=GetOGLPos(...)-vCamEye; vDir.normalize();If you use ortho projection, i dont understand why do you bother by calculating with OGLPos ?!
That's my problem, this code works well only in ortho projection and i would use it with gluperspective (not ortho view).
I would convert the viewport coordinates in openGL coordinates with perspective (gluPerspective (45,(float)width/(float)height,1,100)) (not ortho mode).
I would convert the viewport coordinates in openGL coordinates with perspective (gluPerspective (45,(float)width/(float)height,1,100)) (not ortho mode).
It should definitely work with perspective view as well.
Porbably matrix states for GL_PROJECTION has changed just before your GetOGLPos() call.
Porbably matrix states for GL_PROJECTION has changed just before your GetOGLPos() call.
Author
So that mean i don't use correctly this code ... ok.
I call the projection matrix only in the resize code in WM_SIZE and in the picking code.
I put this code in the draw part of my code after
glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glMatrixMode (GL_MODELVIEW);
glLoadIdentity ();
and before
SwapBuffers (DC);
if someone know how to use GetOGLPos plz help me
I call the projection matrix only in the resize code in WM_SIZE and in the picking code.
I put this code in the draw part of my code after
glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glMatrixMode (GL_MODELVIEW);
glLoadIdentity ();
and before
SwapBuffers (DC);
if someone know how to use GetOGLPos plz help me
This topic is closed to new replies.
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