Dark Bit Factory & Gravity
PROGRAMMING => General coding questions => Topic started by: Pixel_Outlaw on December 22, 2008
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I know how to set a light in OpenGL but I cannot quite figure out how to set a directional vector for it.
I whipped this up in AutoCAD to show what I mean. The view here is isometric to show how the light rises above the canvas then points back down at an angle. I've checked on line documentation but find it a bit confusing. Now I could be wrong but I think AutoCAD uses OpenGL to render in this old version so hopefully the effects will be transferable.
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For directional lights you simply set the 4th component of the light's position to zero which will set it infinitely far away.
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Wouldn't the lights have no direction if they were infinitely far away?
The light I need should rise above the drawing area and shine back down on the drawing. The drawing is what I want even though it was done in a drafting program. It is isometric to show how the light is positioned. By default the lights make everything appear fully lit because I assume the default view is parallel to the light source.
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Even if it's at infinity you can still tell the direction (just like the sun), so all light-rays are parallel which is exactly what you want.
See here (http://jerome.jouvie.free.fr/OpenGl/Tutorials/Tutorial13.php) and have a look at homogenous coordinates (http://en.wikipedia.org/wiki/Homogeneous_coordinates).
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GREAT thanks!
Have some karma.