Unity&Shader案例篇—火焰

一、前言

1、效果图如图所示：



2、使用的Unity版本为Unity5.3.3
二、制作方法
1、C#部分的代码如下：

using UnityEngine;
using System.Collections;

[ExecuteInEditMode]
public class CamRendImage : MonoBehaviour {

[SerializeField]
private Material m_mat;

// Use this for initialization
void Start () {
}

// Update is called once per frame
void Update () {

}
void OnRenderImage(RenderTexture src,RenderTexture dest)
{
Graphics.Blit (src,dest,m_mat);
}
void OnMouseDown()
{

}
void OnMouseUp()
{

}
}

2、Shader代码如下：

Shader "Unlit/Flame"
{
Properties{

}

CGINCLUDE
#include "UnityCG.cginc"
#pragma target 3.0

#define vec2 float2
#define vec3 float3
#define vec4 float4
#define mat2 float2x2
#define mat3 float3x3
#define mat4 float4x4
#define iGlobalTime _Time.y
#define mod fmod
#define mix lerp
#define fract frac
#define texture2D tex2D
#define iResolution _ScreenParams
#define gl_FragCoord ((_iParam.scrPos.xy/_iParam.scrPos.w) * _ScreenParams.xy)

#define PI2 6.28318530718
#define pi 3.14159265358979
#define halfpi (pi * 0.5)
#define oneoverpi (1.0 / pi)

vec4 main(in vec2 fragCoord );

struct v2f {
float4 pos : SV_POSITION;
float4 scrPos : TEXCOORD0;
};

v2f vert(appdata_base v) {
v2f o;
o.pos = mul (UNITY_MATRIX_MVP, v.vertex);
o.scrPos = ComputeScreenPos(o.pos);
return o;
}

fixed4 frag(v2f _iParam) : COLOR0 {
vec2 fragCoord = gl_FragCoord;
return main(gl_FragCoord);
}

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,iGlobalTime*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);
}

vec4 main(in vec2 fragCoord )
{
vec4 fragColor;
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(1.0,0.5,0.1,1.0), vec4(0.1,0.5,1.0,1.0), p.y*0.02+0.4);

fragColor = mix(vec4(0,0,0,0), 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.));
return fragColor;
}

ENDCG

SubShader {
Pass {
CGPROGRAM

#pragma vertex vert
#pragma fragment frag
#pragma fragmentoption ARB_precision_hint_fastest

ENDCG

}
}
FallBack Off
}

将1中的C#脚本赋给主摄像机，然后将附有2中的Shader的材质赋值给C#脚本中的“m_mat”变量。