Unity shader - Laser special effect shader[easy to understand]

Hello everyone , I meet you again , I'm your friend, Quan Jun .

Study Shader It has been several months ,Shader As a door GPU Programming languages are really hard to learn . The main reason after my thinking is that my own computer graphics and art foundation is not solid . So helpless , As a programmer who only wrote code by hand before, I really feel bad .

Learning period , I also want to Shader Great God asks for learning experience , Most of the responses I received were to let me study computer graphics well . ha-ha , So , I went to see computer graphics for more than a month . Then come back to study again Shader, But although it is better than before , But in most cases, his eyes are black .

So , I also thought of the famous saying of a great man : Practice is the only way to get truth . ha-ha , Don't hit me , I didn't mean to talk nonsense （ Actually, it's intentional ..... Come and hit me ）. So how can we learn when the foundation is not very solid Shader Well ？ I thought for a long time , After watching CSDN Shader The little girl who eats watermelon ( Don't hit me , The name of the great God is too long .....)” Mother said that girls should stand on their own ” After the blog of , I seem to have found a little inspiration . I decided to Unity The built-in Shader Start with , Introduce in detail some of the good and practical effects I have seen Shader. I also hope that all gods can criticize and guide what I write , Let us novices improve and make progress together , ha-ha .

Temporarily because of work , I'm going to update it at the rate of one article per week , It depends on the future arrangement , I will cheer up .....

This time, let's take a look at one I used when I was practicing in a project recently shader:

See the figure below for the effect :

This is a laser special effect I made before Shader, It's for hand training .

shader The main code of is as follows :

Shader "Particles/Additive" {
Properties {
	_TintColor ("Tint Color", Color) = (0.5,0.5,0.5,0.5)
	_MainTex ("Particle Texture", 2D) = "white" {}
	_InvFade ("Soft Particles Factor", Range(0.01,3.0)) = 1.0
}

Category {
	Tags { "Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent" }
	Blend SrcAlpha One
	ColorMask RGB
	Cull Off Lighting Off ZWrite Off
	
	SubShader {
		Pass {
		
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			#pragma multi_compile_particles
			#pragma multi_compile_fog

			#include "UnityCG.cginc"

			sampler2D _MainTex;
			fixed4 _TintColor;
			
			struct appdata_t {
				float4 vertex : POSITION;
				fixed4 color : COLOR;
				float2 texcoord : TEXCOORD0;
			};

			struct v2f {
				float4 vertex : SV_POSITION;
				fixed4 color : COLOR;
				float2 texcoord : TEXCOORD0;
				UNITY_FOG_COORDS(1)
				#ifdef SOFTPARTICLES_ON
				float4 projPos : TEXCOORD2;
				#endif
			};
			
			float4 _MainTex_ST;

			v2f vert (appdata_t v)
			{
				v2f o;
				o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
				#ifdef SOFTPARTICLES_ON
				o.projPos = ComputeScreenPos (o.vertex);
				COMPUTE_EYEDEPTH(o.projPos.z);
				#endif
				o.color = v.color;
				o.texcoord = TRANSFORM_TEX(v.texcoord,_MainTex);
				UNITY_TRANSFER_FOG(o,o.vertex);
				return o;
			}

			sampler2D_float _CameraDepthTexture;
			float _InvFade;
			
			fixed4 frag (v2f i) : SV_Target
			{
				#ifdef SOFTPARTICLES_ON
				float sceneZ = LinearEyeDepth (SAMPLE_DEPTH_TEXTURE_PROJ(_CameraDepthTexture, UNITY_PROJ_COORD(i.projPos)));
				float partZ = i.projPos.z;
				float fade = saturate (_InvFade * (sceneZ-partZ));
				i.color.a *= fade;
				#endif
				
				fixed4 col = 2.0f * i.color * _TintColor * tex2D(_MainTex, i.texcoord);
				UNITY_APPLY_FOG_COLOR(i.fogCoord, col, fixed4(0,0,0,0)); // fog towards black due to our blend mode
				return col;
			}
			ENDCG 
		}
	}	
}
}

Copy

This Shader You gods can see it at a glance , I won't pretend that I wrote it , Otherwise, I'm estimated to be beaten in the face by all kinds of slap slap slap mercilessly , Ha ha ha ha ha ha . This is a Unity Bring one with you Shader, The main functions are color mixing , Turn on the fog effect , Plus transparency . Have to say Unity Self contained shader Really amazing. , It's really not easy to write so many functions so succinctly .

I'll stop gossiping and talking more , Otherwise, you may be killed , Ha ha ha ha ha ha ha . Because I also want to write an article to consolidate the foundation , So don't dislike me for being verbose , Then I'll talk more .

_TintColor (“Tint Color”, Color) = (0.5,0.5,0.5,0.5) This sentence is in Shader The color set in the panel to mix , There is a RGBA The default value of .

_MainTex (“Particle Texture”, 2D) = “white” {} This is Shader Set the picture for color mixing in the panel .

_InvFade (“Soft Particles Factor”, Range(0.01,3.0)) = 1.0 This is the value of setting a range , It is used to let others adjust the final effect , Because it's better to let some professional people adjust some effects .

Tags { “Queue”=”Transparent” “IgnoreProjector”=”True” “RenderType”=”Transparent” } “Queue”=”Transparent” This sentence means to open the path of transparency ,”IgnoreProjector”=”True”

It means to turn on the effect of shadow ,”RenderType”=”Transparent” Is the category that enables rendering .

Blend SrcAlpha One Only this type alphaa Mixed mode , In fact, this is the sum of the color value you get and alpha Just a formula for mixing , It's just a shorthand . ColorMask RGB Color channel mask , It means that the last output color channel is RGB passageway Cull Off Lighting Off ZWrite Off Turn off culling Turn off the effect of light Turn off the depth cache （ This operation will actually cause some problems ）

struct appdata_t { float4 vertex : POSITION; fixed4 color : COLOR; float2 texcoord : TEXCOORD0; };

struct v2f { float4 vertex : SV_POSITION; fixed4 color : COLOR; float2 texcoord : TEXCOORD0; UNITY_FOG_COORDS(1) #ifdef SOFTPARTICLES_ON float4 projPos : TEXCOORD2; #endif };

These are actually defined attribute values , I won't list them all , ha-ha .

float4 _MainTex_ST; Don't look at this, there is only this little sentence , In fact, there are many famous halls inside .

indeed for any texture property, Unity provides value for float4 with “_ST” suffix. The x,y contains texture scale, and z,w contains translation (offset).

　　_ST The variables are 4 It's worth ,xy yes texture scale,zw yes offset.

　　 stay Material Can be set in Tiling Namely xy,Offset Namely zw.

From this we can see that , although Unity Self contained Shader Very concise code , It looks much simpler than those thousands of lines of code that can't move , But it actually secretly helps us package a lot of things , This also lets us learn unity Bring their own shader It's a lot more difficult . therefore , This is why I want to write this blog .

v2f vert (appdata_t v) This sentence means fixed-point shader , The returned value is what we defined above v2f attribute , Speaking of this, I can't help but roast . Used a while ago unity Self contained surface shader, I have defined an attribute , The result is not in the fixed-point shader , That is to say vert It gives him the initial value , therefore shader Has been reporting a mistake , My day, . Fortunately, in the end , Our brilliant God came to help me solve this problem .....

o.vertex = mul(UNITY_MATRIX_MVP, v.vertex); This is a MVP Transformation matrix , It means to change the fixed-point coordinates from the world coordinate system , Transform into screen coordinate system , This contains at least three transformation matrices , The code will be very long , Thank you almighty Unity It's sealed for us .( Although I'm not sure Unity Encapsulated or CG This language encapsulates , But let me pretend to be a little bit forced here ...... Think of the famous saying of a friend of mine : What's the difference between people who don't pretend to be forced and salted fish Ha ha ha ha ha ha ha ).

#ifdef SOFTPARTICLES_ON o.projPos = ComputeScreenPos (o.vertex); COMPUTE_EYEDEPTH(o.projPos.z); #endif o.color = v.color; o.texcoord = TRANSFORM_TEX(v.texcoord,_MainTex); UNITY_TRANSFER_FOG(o,o.vertex);

The meaning of this code is based on z To control the scaling and rotation of the special effects , This is a Unity 5.0 It contains new shader, There are many things in it , All we see is the parameters passed into the method by ourselves . See our super powerful Yusong for details MOMO The blog of , There are explanations http://www.xuanyusong.com/?p=3486( Mercilessly throw the pot Ha ha ha ha ha ha ha )

float _InvFade; Look directly at the code _InvFade, This is a parameter that controls transparency ( Match the difference between the depth of particles far and near the screen and the depth of the scene to present the effect ) It is similar to a professional explanation of the great God of Art unreal Of alpha bias Material nodes , Used to soften the interface between particle side and solid , Avoid intersecting lines with patches .

#ifdef SOFTPARTICLES_ON float sceneZ = LinearEyeDepth (SAMPLE_DEPTH_TEXTURE_PROJ(_CameraDepthTexture, UNITY_PROJ_COORD(i.projPos))); float partZ = i.projPos.z; float fade = saturate (_InvFade * (sceneZ-partZ)); i.color.a *= fade; #endif

This sentence is a way to show the effect of special effects on the depth of the scene and the distance from the screen . Everyone can see it from here , This Shader In fact, it is a special one for special effects Shader, Similar to laser or 2D The knife light effect in the game can be made using this method , Tell you a little secret , quite a lot Unity The above special effect plug-ins use this Shader To make the , Ha ha ha ha ha ha ha .

fixed4 col = 2.0f * i.color * _TintColor * tex2D(_MainTex, i.texcoord); The meaning of this sentence is to deal with the previous series i.color For simple color blending , As for that 2.0f, In fact, that is to write this shader The great God defined it when he adjusted the color . Computer graphics is actually a subject that deceives people's eyes to a great extent , Ha ha ha ha ha ha ha .

UNITY_APPLY_FOG_COLOR(i.fogCoord, col, fixed4(0,0,0,0)); This sentence means setting the orientation and color of the fog , In fact, this is also Unity A self-contained method of encapsulating fog .

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