how to build a light vop from scratch? wip

[kensonuken]

Im trying to build a custom light vop and started to build one.. I request you guys to help me out in building this light vop... I will be uploading the hip files..

[kensonuken]

Im trying to build a custom light vop and started to build one.. I request you guys to help me out in building this light vop... I will be uploading the hip files..

This is the shader which im trying to build

light
pointlight( 
	float intensity = 1;
	color lightcolor = 1;
	point from = point "shader" (0,0,0);
	float decay = 2.0; )
{
	illuminate( from )
	{
		float distance_squared = L.L;

		if( decay == 2.0 )
		{
			Cl = intensity * lightcolor / distance_squared;
		}
		else
		{
			Cl = intensity * lightcolor / pow(distance_squared, 0.5 * decay ); 
		}
	}
}

[kensonuken]

Im not able to find the illuminate node in vop ... how do i move further?

[Jason]

Im not able to find the illuminate node in vop ... how do i move further?

In VEX you dont need it.

Why not check out the source code the VEX Light SHOPs and learn from those? There is so much info right there.

[kensonuken]

yeah jason I know but I want to make lots of additional functions which i feel better to build it using vops and add them quickly. As of now I have only one thing to add to the existing light shaders thats projecting the UV texture over the object and render them into saparate pass for each light.. I dont know if things can work like taking Cl and multiplying with uvs or howz the solve this problem... I dont want to use some rendered texture and plug it in the light node but to generate it procedurally so that It will not generate any sub pixel artifacts during the interpolation...

Edited March 4, 2009 by kensonuken

[Jason]

What I mean is to learn from VEX function set, the language structure from the VEX source code, particularly how it differs from RSL - and then build it in VOPs like you want it. If you look through the Light shaders in VEX, you'll see that there are no illuminate constructs in there.

It seems like you're running before you're walking. There is some fundamental groundwork you need to know before building some of these shaders.

[Jason]

Hey Kensonuken,

Did you manage to get something going?

[kensonuken]

yeah I saw the sample shader code in the shop I understood how it works and Im trying to plug UV map (procedural). I am a bit confused..

it should be multiplied by Cl but I want to take that out as another pass called Proj so im thinking to write that out as some Proj = Cl * Uvmap just getting confused how to code this...

[kensonuken]

i could build this shader but this is showing only the UVs of the object instead of just a uv projection streching across the cone angle...

light
light1()
{
    float       amount;
    vector      vec;
    float       amount1;
    vector      vec1;
    vector      sum;

    // Code produced by: ramps1
    float ss;
    vop_bindS(ss, s, 1);
    ss = ss*1 - 0;
    if (1 != 0)
        amount = vop_TentTrain(ss*.5, 1*vop_FilterWidth(ss));
    else
        amount = vop_RampTrain(ss, 1*vop_FilterWidth(ss));

    // Code produced by: floattovec1
    vec = vop_floattovec(amount, amount, amount);

    // Code produced by: ramps2
    float ss1;
    vop_bindS(ss1, t, 1);
    ss1 = ss1*1 - 0;
    if (1 != 0)
        amount1 = vop_TentTrain(ss1*.5, 1*vop_FilterWidth(ss1));
    else
        amount1 = vop_RampTrain(ss1, 1*vop_FilterWidth(ss1));

    // Code produced by: floattovec2
    vec1 = vop_floattovec(amount1, amount1, amount1);

    // Code produced by: add1
    sum = vec + vec1;

    // Code produced by: output1
    vector tempCl = sum;
    Cl = tempCl;
}

[kensonuken]

here is the output...

[kensonuken]

I am trying to get this kind of look

just to project UV map..

[Wolfwood]

I am trying to get this kind of look

just to project UV map..

To make a projector light, you just need to wire Ps into a Transform VOP, and change the space to "space:lightndc", the x/y components are what you want.