View Full Version : Problem in lightening

02-10-2003, 07:19 AM
I have my own model ( with its own model matrices...)Now the problem is ...

I am using the function..

ApplyLightPosition(float *pArrPos)
DumpArrayLogf("ApplyLightPosition\n", pArrPos ,4); // My own debug function
// position being set separately
glLightfv(glLightId , GL_POSITION, pArrPos);

I am using directional light , so pArrPos[3] = 0;

My test cases / approaches are as follow...

1) My display on some machines is flattened.... If I change the pArrPos[3] = 1. I can see a lightened display , But I want to keep directional lightening.

2) Then I tried offscreen rendering , the display is flattened consistently... I checked my matrices, they are correct...

3) I tried some experimenting like making some change in pArrPos[0]( like I subtracted some random value from it , like 10 ). I could see the model rendered.

I imagine a situation such taht the light is being moved away to infinity by OpenGl....This may be wrong....

I am still a begineer at OpenGl... need help ... thanks in advance....

02-11-2003, 02:48 AM

Two cases where this could happen (and I'm not even sure about them) are:

1. Your light position is (0, 0, 0), making that directional doesn't make a sense.

2. Your light has some attenuation, which makes the light contribution always zero, when the light is at infinity.

If it's neither, I'm afraid I can't help you.