Particles receiving shadows?

powdered_swords · May 5, 2013, 5:51am

Does anyone know if it’s possible for vertex lit particles to be affected by shadows generated by geometry? I made a small demo testing the functionality of vertex lit particles

Unfortunately while I could get the particles to project shadows onto the two surfaces the opposite was not true.

Daniel-Brauer · May 6, 2013, 2:36pm

Vertex lighting does not support receiving shadows; you need per-pixel lighting for that.

Farfarer · May 6, 2013, 2:46pm

Give this a try?

gist.github.com

https://gist.github.com/Farfarer/158b23f694c2c995f93e

AutoLightParticle.cginc

// Helper macros specific to particles for lighting and shadows.
// Required.
// Keep this in the same directory as the other lit particle shader files.

#ifdef AUTOLIGHT_INCLUDED
	
	// ---- Screen space shadows
	#if defined (SHADOWS_SCREEN)
		#define TRANSFER_SHADOW_PARTICLE(a) a._ShadowCoord = ComputeScreenPos(o.pos);
	#endif

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Camera2World.js

#pragma strict

// Apply this to all of the cameras that will be rendering lit particles.

function OnPreCull () {
	Shader.SetGlobalMatrix ("_Camera2World", this.camera.cameraToWorldMatrix );
}

litParticleAdditive.shader

// Additive particle.
// Does not receive shadows.

Shader "Custom/Lit Particle Additive" {

	Properties {
		_Color ("Main Color", Color) = (1.0, 1.0, 1.0, 1.0)
		_MainTex ("Color (RGBA)", 2D) = "white" {}
	}

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powdered_swords · May 7, 2013, 11:06am

Thanks! I’ll use this as soon as I can read through it and figure out how it works

Farfarer · May 7, 2013, 12:28pm

It’s a bit flakey (which is why it’s a secret, rather than public gist). But it should help.

reecpj · April 18, 2014, 9:42pm

This looks really interesting Farfarer (sorry it’s been so long since you posted) but how could I get it working with multi_compile_fwdadd_fullshadows in the ForwardAdd pass for spotlight shadows?
It says: “Custom/Lit Particle Additive’: Program ‘vert’, unable to find compatible overloaded function “mul(float4x4[4], float4)” at line 116”
but still renders ok. That line is TRANSFER_VERTEX_TO_FRAGMENT_PARTICLE(o); which expands to
#define TRANSFER_VERTEX_TO_FRAGMENT_PARTICLE(a) a._LightCoord = mul(_LightMatrix0, posW); TRANSFER_SHADOW_PARTICLE(a)

Currently the particles seem to be evaluating the shadow map in camera space or something - I have to zoom out and rotate around for any light to show up - certainly they don’t respond as if they are in world space. I’d really appreciate some help, you’ve done a lot for my shader education already!

reecpj · April 19, 2014, 7:03pm

Never mind, I got it working (using my own shadow maps rather than Unity’s) - I didn’t realise the shuriken particles were in camera space, so you can multiply them by the camera to world matrix to get them in world space. Thanks!

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Particles receiving shadows?

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