Simple 2d shadows?

BlitzMax Forums/OpenGL Module/Simple 2d shadows?

Retimer

(Posted 2008) [#1]

How can I achieve this with opengl lighting? I have a simple lighting system which I played with from an example that was on the forums using:

glEnable GL_LIGHTING
glEnable GL_LIGHT0	
Global l0_diffuse:Float[] =[0.0, 1.7, 0.0, 1.0]

glLightf GL_LIGHT0, GL_CONSTANT_ATTENUATION, 0.0
glLightf GL_LIGHT0, GL_LINEAR_ATTENUATION, 0.001
glLightf GL_LIGHT0, GL_QUADRATIC_ATTENUATION, 0.0001


l1_position[0] = 100
l1_position[1] = 100			
glLightfv GL_LIGHT1, GL_POSITION, l1_position

With that I was able to create a quick lighting system, but how would I create a simple shadow using these lights (rather than fake shadows via polygons)? Not looking for texture/sprite shadows, but being able to create walls with a couple vectors to cast a nice shadow, based on the light source.

Can someone provide a very small example of this, or a link to one?

Dreamora

(Posted 2008) [#2]

You won't
That are vertex lights, they don't do anything else than make vertices getting colored with their own light basing on the distance and falloff method.

If you want shadows in 2D then "fake shadows" (there is a module for that) are the only way to do it.

True shadow needs 3D + Stencil / shader.

Retimer

(Posted 2008) [#3]

Edit:

Nevermind. Polygons work better than I thought. Thanks