Const positioned light with GLKBaseEffect

Question

I need to set const spot light position with GLKBaseEffect: so when I change modelview, light stays in the same place. How can I achieve this?

score 1 · Answer 1 · answered Dec 23 '12 at 10:45

1

When you set the position of a light using GLKBaseEffect, it uses the value currently stored in its modelviewMatrix property. So, you need to set this value twice, once for the light and once for your object:

self.effect.transform.modelviewMatrix = GLKMatrix4Identity;
self.effect.light1.position = GLKVector4Make(0.0, 1.0, 3.0, 1);

GLKMatrix4 modelViewMatrix = GLKMatrix4MakeTranslation(0.0f, 0.0f, -3.0f);
modelViewMatrix = GLKMatrix4Rotate(modelViewMatrix, GLKMathDegreesToRadians(90), 0, 1, 0);
self.effect.transform.modelviewMatrix = modelViewMatrix;

That should do the trick

answered Dec 23 '12 at 10:45

Ricardo RendonCepeda

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Hmm. Solution is wrong for me. Seems that subsequent modelview modification affects light also (for OpenGL 1.0 it's as excepted and `GLKBaseEffect` tries to emulate it). – kpower Dec 28 '12 at 07:13
1

I'll have look, but in my project this works fine when declared inside the draw function. I admit I mostly use OpenGL ES 2.0 shaders precisely because I know what my code is doing. Although GLKBaseEffect emulates OpenGL ES 1.1, a lot of the implementation details are quite tricky and hidden. Shaders all the way! – Ricardo RendonCepeda Dec 28 '12 at 14:58
Quite agree with you. But for now I simply want to save time: I don't know GLSL and want to simply make first apps version ASAP. – kpower Dec 28 '12 at 16:29

score 0 · Accepted Answer · answered Nov 13 '13 at 03:49

0

The only solution helped me here was to make own shaders.

answered Nov 13 '13 at 03:49

kpower

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Const positioned light with GLKBaseEffect

2 Answers2