Is normal matrix recomputed automatically?

Graphics and GPU Programming Programming

Started by Prune March 04, 2010 11:52 AM

4 comments, last by V-man 14 years, 1 month ago

224

Author

March 04, 2010 11:52 AM

If I do a glLoadMatrixf on the modelview matrix in the program, will gl_NormalMatrix be correct in the shader, that is, is it computed automatically any time the projection or modelview are changed? Thanks

"But who prays for Satan? Who, in eighteen centuries, has had the common humanity to pray for the one sinner that needed it most?" --Mark Twain

~~~~~~~~~~~~~~~Looking for a high-performance, easy to use, and lightweight math library? http://www.cmldev.net/ (note: I'm not associated with that project; just a user)

HuntsMan

370

March 04, 2010 12:33 PM

Yes.

vincoof

514

March 05, 2010 07:59 AM

Sure it does.

But please note that gl_NormalMatrix is supported with compatibility profile only, which should not be a problem for desktop graphics cards since all of them support this profile, and if a graphics card vendor ever tried to stop the support he would lose a massive number of gamers (which are "customers" for them).

This could be a problem for other devices such as mobile platforms, though.

[Edited by - vincoof on March 5, 2010 8:59:30 AM]

V-man

813

March 05, 2010 01:55 PM

I would avoid using gl_NormalMatrix and any other built in stuff if I were you. Even glLoadMatrix should be avoided.

Sig: http://glhlib.sourceforge.net
an open source GLU replacement library. Much more modern than GLU.
float matrix[16], inverse_matrix[16];
glhLoadIdentityf2(matrix);
glhTranslatef2(matrix, 0.0, 0.0, 5.0);
glhRotateAboutXf2(matrix, angleInRadians);
glhScalef2(matrix, 1.0, 1.0, -1.0);
glhQuickInvertMatrixf2(matrix, inverse_matrix);
glUniformMatrix4fv(uniformLocation1, 1, FALSE, matrix);
glUniformMatrix4fv(uniformLocation2, 1, FALSE, inverse_matrix);

AlexSud

100

March 06, 2010 02:04 AM

Quote:Original post by V-man
I would avoid using gl_NormalMatrix and any other built in stuff if I were you. Even glLoadMatrix should be avoided.

Hm,what's wrong with glLoadMatrix?I've been using it for pretty long time and don't remember that it caused any problems^^

V-man

813

March 06, 2010 07:38 AM

Because if you are using glLoadMatrix, then that means you are using ftransform() or gl_Projec.... and other junk.

Is normal matrix recomputed automatically?

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Is normal matrix recomputed automatically?

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