分享一个GLSL转换的火Shader

先看效果：

 

GLSL代码：

float noise(vec3 p) //Thx to Las^Mercury
{
	vec3 i = floor(p);
	vec4 a = dot(i, vec3(1., 57., 21.)) + vec4(0., 57., 21., 78.);
	vec3 f = cos((p-i)*acos(-1.))*(-.5)+.5;
	a = mix(sin(cos(a)*a),sin(cos(1.+a)*(1.+a)), f.x);
	a.xy = mix(a.xz, a.yw, f.y);
	return mix(a.x, a.y, f.z);
}

float sphere(vec3 p, vec4 spr)
{
	return length(spr.xyz-p) - spr.w;
}

float flame(vec3 p)
{
	float d = sphere(p*vec3(1.,.5,1.), vec4(.0,-1.,.0,1.));
	return d + (noise(p+vec3(.0,iTime*2.,.0)) + noise(p*3.)*.5)*.25*(p.y) ;
}

float scene(vec3 p)
{
	return min(100.-length(p) , abs(flame(p)) );
}

vec4 raymarch(vec3 org, vec3 dir)
{
	float d = 0.0, glow = 0.0, eps = 0.02;
	vec3  p = org;
	bool glowed = false;
	
	for(int i=0; i<64; i++)
	{
		d = scene(p) + eps;
		p += d * dir;
		if( d>eps )
		{
			if(flame(p) < .0)
				glowed=true;
			if(glowed)
       			glow = float(i)/64.;
		}
	}
	return vec4(p,glow);
}

void mainImage( out vec4 fragColor, in vec2 fragCoord )
{
	vec2 v = -1.0 + 2.0 * fragCoord.xy / iResolution.xy;
	v.x *= iResolution.x/iResolution.y;
	
	vec3 org = vec3(0., -2., 4.);
	vec3 dir = normalize(vec3(v.x*1.6, -v.y, -1.5));
	
	vec4 p = raymarch(org, dir);
	float glow = p.w;
	
	vec4 col = mix(vec4(1.,.5,.1,1.), vec4(0.1,.5,1.,1.), p.y*.02+.4);
	
	fragColor = mix(vec4(0.), col, pow(glow*2.,4.));
	//fragColor = mix(vec4(1.), mix(vec4(1.,.5,.1,1.),vec4(0.1,.5,1.,1.),p.y*.02+.4), pow(glow*2.,4.));

}

转换成的Shader代码：

Shader "Hidden/Fire"
{
	Properties
	{
		_MainTex ("Texture", 2D) = "white" {}
	}
	SubShader
	{
		// No culling or depth
		Cull Off ZWrite Off ZTest Always

		Pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			
			#include "UnityCG.cginc"

			struct appdata
			{
				float4 vertex : POSITION;
				float2 uv : TEXCOORD0;
			};

			struct v2f
			{
				float2 uv : TEXCOORD0;
				float4 vertex : SV_POSITION;
			};

			v2f vert (appdata v)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				o.uv = v.uv;
				return o;
			}
			float noise(float3 p) //Thx to Las^Mercury
{
	float3 i = floor(p);
	float4 a = dot(i, float3(1., 57., 21.)) + float4(0., 57., 21., 78.);
	float3 f = cos((p-i)*acos(-1.))*(-.5)+.5;
	a = lerp(sin(cos(a)*a),sin(cos(1.+a)*(1.+a)), f.x);
	a.xy = lerp(a.xz, a.yw, f.y);
	return lerp(a.x, a.y, f.z);
}

float sphere(float3 p, float4 spr)
{
	return length(spr.xyz-p) - spr.w;
}

float flame(float3 p)
{
	float d = sphere(p*float3(1.,.5,1.), float4(.0,-1.,.0,1.));
	return d + (noise(p+float3(.0,_Time.y *2.,.0)) + noise(p*3.)*.5)*.25*(p.y) ;
}

float scene(float3 p)
{
	return min(100.-length(p) , abs(flame(p)) );
}

float4 raymarch(float3 org, float3 dir)
{
	float d = 0.0, glow = 0.0, eps = 0.02;
	float3  p = org;
	bool glowed = false;
	
	for(int i=0; i<64; i++)
	{
		d = scene(p) + eps;
		p += d * dir;
		if( d>eps )
		{
			if(flame(p) < .0)
				glowed=true;
			if(glowed)
       			glow = float(i)/64.;
		}
	}
	return float4(p,glow);
}
			sampler2D _MainTex;

			fixed4 frag (v2f i) : SV_Target
			{
				float2 v = -1.0 + 2.0 *i.uv ;

	
	float3 org = float3(0., -2., 4.);
	float3 dir = normalize(float3(v.x*1.6, -v.y, -1.5));
	
	float4 p = raymarch(org, dir);
	float glow = p.w;
	
	float4 col = lerp(float4(1.,.5,.1,1.), float4(0.1,.5,1.,1.), p.y*.02+.4);
	
       return  lerp(float4(0.,0.,0.,0.), col, pow(glow*2.,4.));
	//fragColor = lerp(float4(1.), lerp(float4(1.,.5,.1,1.),float4(0.1,.5,1.,1.),p.y*.02+.4), pow(glow*2.,4.));

			}
			ENDCG
		}
	}
}

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