【Unity】uGUI 用 Dissolve Shader

ノイズテクスチャを使って uGUI で Dissolve っぽい表現をやってみたかったので

Unity2020 の uGUI Shader をもとに作成してみました

使い方

以下の Shader を作成してから、以下のコンポーネントを Image がある GameObejct に追加し

よしななノイズテクスチャをセットすることで、Show もしくは Hide を呼び出せばいい感じに表示非表示をしてくれます

Dissolve の判定に使ってるのは r 成分だけなので、b g はどんな値が入ってても影響はありません

シェーダーコード

// Unity built-in shader source. Copyright (c) 2016 Unity Technologies. MIT license (see license.txt)

Shader "Hidden/UI/Dissolve"
{
    Properties
    {
        [PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {}
        (_NoiseTex ("Noise Texture", 2D) = "white" {}
        _DissolveTime ("Time", Range(0.0, 1.0)) = 1
        _Color ("Tint", Color) = (1,1,1,1)

        _StencilComp ("Stencil Comparison", Float) = 8
        _Stencil ("Stencil ID", Float) = 0
        _StencilOp ("Stencil Operation", Float) = 0
        _StencilWriteMask ("Stencil Write Mask", Float) = 255
        _StencilReadMask ("Stencil Read Mask", Float) = 255

        _ColorMask ("Color Mask", Float) = 15

        [Toggle(UNITY_UI_ALPHACLIP)] _UseUIAlphaClip ("Use Alpha Clip", Float) = 0
    }

    SubShader
    {
        Tags
        {
            "Queue"="Transparent"
            "IgnoreProjector"="True"
            "RenderType"="Transparent"
            "PreviewType"="Plane"
            "CanUseSpriteAtlas"="True"
        }

        Stencil
        {
            Ref [_Stencil]
            Comp [_StencilComp]
            Pass [_StencilOp]
            ReadMask [_StencilReadMask]
            WriteMask [_StencilWriteMask]
        }

        Cull Off
        Lighting Off
        ZWrite Off
        ZTest [unity_GUIZTestMode]
        Blend One OneMinusSrcAlpha
        ColorMask [_ColorMask]

        Pass
        {
            Name "Default"
        CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #pragma target 2.0

            #include "UnityCG.cginc"
            #include "UnityUI.cginc"

            #pragma multi_compile_local _ UNITY_UI_CLIP_RECT
            #pragma multi_compile_local _ UNITY_UI_ALPHACLIP

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

            struct v2f
            {
                float4 vertex   : SV_POSITION;
                fixed4 color    : COLOR;
                float2 texcoord  : TEXCOORD0;
                float4 worldPosition : TEXCOORD1;
                half4  mask : TEXCOORD2;
                UNITY_VERTEX_OUTPUT_STEREO
            };

            sampler2D _MainTex;
            sampler2D (_NoiseTex;
            fixed4 _Color;
            fixed4 _TextureSampleAdd;
            float4 _ClipRect;
            float4 _MainTex_ST;
            float _UIMaskSoftnessX;
            float _UIMaskSoftnessY;
            float _DissolveTime;

            v2f vert(appdata_t v)
            {
                v2f OUT;
                UNITY_SETUP_INSTANCE_ID(v);
                UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(OUT);
                float4 vPosition = UnityObjectToClipPos(v.vertex);
                OUT.worldPosition = v.vertex;
                OUT.vertex = vPosition;

                float2 pixelSize = vPosition.w;
                pixelSize /= float2(1, 1) * abs(mul((float2x2)UNITY_MATRIX_P, _ScreenParams.xy));

                float4 clampedRect = clamp(_ClipRect, -2e10, 2e10);
                float2 maskUV = (v.vertex.xy - clampedRect.xy) / (clampedRect.zw - clampedRect.xy);
                OUT.texcoord = TRANSFORM_TEX(v.texcoord.xy, _MainTex);
                OUT.mask = half4(v.vertex.xy * 2 - clampedRect.xy - clampedRect.zw, 0.25 / (0.25 * half2(_UIMaskSoftnessX, _UIMaskSoftnessY) + abs(pixelSize.xy)));

                OUT.color = v.color * _Color;
                return OUT;
            }

            fixed4 frag(v2f IN) : SV_Target
            {
                // もともとのテクスチャを取得
                half4 color = IN.color * (tex2D(_MainTex, IN.texcoord) + _TextureSampleAdd);
                // ノイズテクスチャを取得
                half4 noise = IN.color * (tex2D(_NoiseTex, IN.texcoord) + _TextureSampleAdd);

                // いい感じにアルファを調整
                color.a *= smoothstep(noise.r, noise.r + 0.2, _DissolveTime);

                #ifdef UNITY_UI_CLIP_RECT
                half2 m = saturate((_ClipRect.zw - _ClipRect.xy - abs(IN.mask.xy)) * IN.mask.zw);
                color.a *= m.x * m.y;
                #endif

                #ifdef UNITY_UI_ALPHACLIP
                clip (color.a - 0.001);
                #endif

                color.rgb *= color.a;

                return color;
            }
        ENDCG
        }
    }
}

コンポーネントのスクリプト

using UnityEngine;
using UnityEngine.UI;

[RequireComponent(typeof(Image))]
public class UIDissolve : MonoBehaviour
{
    [SerializeField] 
    private Shader _shader;
    [SerializeField]
    private Texture2D _noiseTexture;
 
    [SerializeField] 
    private float _duration = 1f;
 
    [SerializeField, HideInInspector]
    private Image _image;
 
#if UNITY_EDITOR
    private void Reset()
    {
        _image = GetComponent<Image>();
        _shader = Shader.Find("Hidden/UI/Dissolve");
    }
#endif
 
    private Material _createMaterial;
 
    private float _time;
    private static readonly int DissolveTime = Shader.PropertyToID("_DissolveTime");
    private bool _show;
    private static readonly int DissolveTex = Shader.PropertyToID("_DissolveTex");
 
    private void Awake()
    {
        _createMaterial = new Material(_shader);
        _image.material = _createMaterial;
        _createMaterial.SetFloat(DissolveTime, 1);
        _createMaterial.SetTexture(DissolveTex, _noiseTexture);
    }
 
    /// <summary>
    /// 非表示にする
    /// </summary>
    public void Hide()
    {
        _show = false;
        _time = _duration;
    }
     
    /// <summary>
    /// 表示する
    /// </summary>
    public void Show()
    {
        _show = true;
        _time = _duration;
    }
 
    private void Update()
    {
        if (_time <= 0f)
            return;
         
        _time -= Time.deltaTime;
        var value = Mathf.Clamp(_time, 0, _duration) / _duration;
        if (_show) 
            value = 1 - value;
 
        _createMaterial.SetFloat(DissolveTime, value);
    }
}