OPENGL lesson 3

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Started by supercoollee May 08, 2010 03:00 AM

2 comments, last by supercoollee 13 years, 11 months ago

100

Author

May 08, 2010 03:00 AM

i have just started learning OPENGL, i use MASM for programming. in lesson 3, if there isn't a lightsource in the scene, how can the color be shown? and i tried to put up a scene with a lightsource and a triangle, the glColor3x (b or f) function doesn't change the color of the triangle , it always appear gray, i don't know why.

Dubh

122

May 19, 2010 09:37 AM

Can you post some of your code?

Katie

2,255

May 19, 2010 10:01 AM

If you don't enable lighting, the "flat" colours specified by the glColour() will be used.

If you turn on lighting, then the glColor() is ignored -- the default material colour will be used instead. Hence your triangle will be drawn in white; which will end up gray after lighting.

You probably want to enable glColorMaterial which will copy colours out of the glColor() calls into the ambient/diffuse/both material colours.

supercoollee

100

Author

May 20, 2010 02:56 AM

the problem has been solved. in order to specify color at each vertex,

glEnable(GL_COLOR_MATERIAL)

must be called.

and if no light is specified, GL uses the default lighting, that's why in NEHE's lesson3 the colors can be shown without calling lighting functions.