Trunk Shader question - gl_LightSource[1].ambient

[Griff]

in trunk, does gl_LightSource[1] have an ambient colour? i've been trying to use it in a shader and it doesn't seem to add any extra lighting into the final colour, gl_LightSource[0].ambient does, it adds a sort of grey/white light, which is perfectly useable in a shader, but i was wondering if we could have a coloured ambient light to go with our coloured suns.

[another_commander]

I think that the color of the sun becomes also the color of the ambient light. Will have to recheck though. Just look at the main planet of the same system with different sun colors, you should be able to note the ambient color difference.

[Kaks]

Yes, ambient light and sun colour are kept in sync throughout the game.
I'm not 100% sure if gl_LightSource[1] is the one used, but you can assign that to highlight all ship surfaces, then change the sun colour* and see if the highlight colour in the shade changes to match the new sun colour.

*Yep, you can change sun & ambient light colour in real time now typing
system.info.sun_color=whatever
inside the debug console!

[Griff]

I tried a test at Lave by fiddling with a fragment shader, the cobraIII on the left has the ambient from light 0 added to it

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diffuse += gl_FrontMaterial.ambient * gl_LightSource[0].ambient;

and the CobraIII on the right uses lightsource 1's ambient instead

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diffuse += gl_FrontMaterial.ambient * gl_LightSource[1].ambient;

It's not a big deal, i've just been noticing that some of the suns in trunk have really lovely colours to them these days and was playing about trying to get the lighting in the shaders to match

[Kaks]

I've just found out the relevant bit of code:

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	GLfloat		sun_ambient[] = { 0.0, 0.0, 0.0, 1.0};	// ambient light about 5%
	sun_diffuse[0] = 0.5 * (1.0 + r);	// paler
	sun_diffuse[1] = 0.5 * (1.0 + g);	// paler
	sun_diffuse[2] = 0.5 * (1.0 + b);	// paler
	sun_diffuse[3] = 1.0;
	sun_specular[0] = r;
	sun_specular[1] = g;
	sun_specular[2] = b;
	sun_specular[3] = 1.0;

	glLightfv(GL_LIGHT1, GL_AMBIENT, sun_ambient);
	glLightfv(GL_LIGHT1, GL_DIFFUSE, sun_diffuse);
	glLightfv(GL_LIGHT1, GL_SPECULAR, sun_specular);

The ambient light is set to pitch black, even though from the comment you'd expect it to be 5% of the sun's colour! Give me a little while, and I'll see what I can do!
Edit: I've 'bumped up' the ambient light to a 'massive' 10%, but in practice there doesn't seem to be much difference. I'll commit that to trunk soon, but you're probably better off using the diffuse colour instead!

[JensAyton]

The real ambient light is in gl_LightModel.ambient, as seen in oolite-default-shader.fragment (this is stars_ambient and GL_LIGHT_MODEL_AMBIENT in Universe.m). The per-light ambient properties are supposed to be zero.

[Griff]

Oops, sorry about that reporting bugs when the fault was in my shader, i hope you didn't go to too much trouble kaks.

so, a quick change of that line in the shader to

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diffuse += gl_FrontMaterial.ambient * gl_LightModel.ambient;

and it's working great!
as an aside, debug.oxp works great on windows7 RC 64-bit

[Kaks]

No problem! And thanks Ahruman for clarifying which ambient light is which!