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Asked: 2026-06-16T00:04:59+00:00

I passed 3 array pointers to opengl with: glColorPointer() glNormalPointer() glVertexPointer() everthing works fine,but

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I passed 3 array pointers to opengl with:

glColorPointer() 
glNormalPointer() 
glVertexPointer()

everthing works fine,but when I try to enable light by glEnable(GL_LIGHT0);

glDrawElements just crashed,I assume there is something wrong with normal? my normal comes from this file:

1.000000 1.000000 -1.000000 0.000000 0.000000 -1.000000
1.000000 -1.000000 -1.000000 0.000000 0.000000 -1.000000
-1.000000 -1.000000 -1.000000 0.000000 0.000000 -1.000000
1.000000 0.999999 1.000000 -0.000000 0.000000 1.000000
-1.000000 1.000000 1.000000 -0.000000 0.000000 1.000000
-1.000000 -1.000000 1.000000 -0.000000 0.000000 1.000000
1.000000 1.000000 -1.000000 1.000000 -0.000001 -0.000000
1.000000 0.999999 1.000000 1.000000 -0.000001 -0.000000
0.999999 -1.000001 1.000000 1.000000 -0.000001 -0.000000
1.000000 -1.000000 -1.000000 -0.000000 -1.000000 -0.000000
0.999999 -1.000001 1.000000 -0.000000 -1.000000 -0.000000
-1.000000 -1.000000 1.000000 -0.000000 -1.000000 -0.000000
-1.000000 -1.000000 -1.000000 -1.000000 0.000000 -0.000000
-1.000000 -1.000000 1.000000 -1.000000 0.000000 -0.000000
-1.000000 1.000000 1.000000 -1.000000 0.000000 -0.000000
1.000000 0.999999 1.000000 0.000000 1.000000 0.000000
1.000000 1.000000 -1.000000 0.000000 1.000000 0.000000
-1.000000 1.000000 -1.000000 0.000000 1.000000 0.000000
-1.000000 1.000000 -1.000000 0.000000 0.000000 -1.000000
0.999999 -1.000001 1.000000 -0.000000 0.000000 1.000000
1.000000 -1.000000 -1.000000 1.000000 0.000000 0.000000
1.000000 1.000000 -1.000000 1.000000 0.000000 0.000000
0.999999 -1.000001 1.000000 1.000000 0.000000 0.000000
-1.000000 -1.000000 -1.000000 -0.000000 -1.000000 0.000000
-1.000000 1.000000 -1.000000 -1.000000 0.000000 -0.000000
-1.000000 1.000000 1.000000 0.000000 1.000000 0.000000

first 3 is vertex position,and last 3 is normal,I have questions:

  1. does the normal changes when I translate or rotate or scale the mesh?

  2. what could cause glDrawElements crash by enable lighting?

3.since my normals come from file,and its already normalized do I have to call glEnable(GL_NORMALIZE) ?

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1 Answer

  1. Editorial Team

    You probably passed invalid arguments to glNormalPointer causing an access violation when glDrawElements tries to access your memory. The old fixed function per-vertex lighting code only makes use of normals when lighting is enabled.

    Regarding your other questions:
    You have to rotate your normals when rotating your mesh. Translations and scaling does not affect normals. This is automatically done by the fixed function pipeline (which I suppose you’re using) and only has to be done manually when writing a custom vertex shader or when rotating the mesh on the CPU. glEnable(GL_NORMALIZE) is only needed when you scale your mesh, otherwise you can discard this function.

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