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OpenGL Lighting, vertex normals and rotation question.

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This is hopefully a simple question, but neither online research, nor looking through the red book has given me an answer. I have a primitive (triangle mesh w. vertex normals) that I would like to arrange in a ring: for (int a=0; a<18; a++ ) { glPushMatrix(); glRotatef(20.0f * a, 0.0, 0.0, 1.0); glVertexPointer(3 , GL_FLOAT, 0, SegmentVerts); glNormalPointer(GL_FLOAT, 0, SegmentVertNorms); glDrawElements(GL_TRIANGLES, numSegmentFaces * 3, GL_UNSIGNED_SHORT, SegmentFaces); glPopMatrix(); } When I do it as above, lighting seems to not take the rotation into account, i.e. all segments seem to get the same lighting, regardless of the rotation. My ligting is as following: - (void)configureLighting; { const GLfloat lightAmbient[] = {0.0f, 0.0f, 0.0f, 0.0f}; const GLfloat lightDiffuse[] = {1.0f, 1.0f, 1.0f, 1.0f}; const GLfloat matAmbient[] = {1.0f, 1.0f, 1.0f, 1.0f}; const GLfloat matDiffuse[] = {1.0f, 1.0f, 1.0f, 1.0f}; const GLfloat matSpecular[] = {0.6f, 0.6f, 0.6f, 1.0f}; const GLfloat lightPosition[] = {0.0f, 0.0f, 10.0f, 0.0f}; const GLfloat lightShininess = 20.0f; glEnable(GL_LIGHTING); glEnable(GL_LIGHT0); glEnable(GL_COLOR_MATERIAL); glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT, matAmbient); glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, matDiffuse); glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, matSpecular); glMaterialf(GL_FRONT_AND_BACK, GL_SHININESS, lightShininess); glLightfv(GL_LIGHT0, GL_AMBIENT, lightAmbient); glLightfv(GL_LIGHT0, GL_DIFFUSE, lightDiffuse); glLightfv(GL_LIGHT0, GL_POSITION, lightPosition); glShadeModel(GL_SMOOTH); } What could I be doing wrong? My impression was that OpenGL ES takes care of adjusting normals to the rotation, or do I have to handle the normals myself? Or am I reusing the SegmentVertNorms memory to early? Any clue or link is much appreciated.

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