[Unity] 画像を移動・拡縮・回転するシェーダー

AffineTransform.shader

Shader "Unlit/AffineTransform"
{
    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
        _PositionX ("Position X", float) = 0.0
        _PositionY ("Position Y", float) = 0.0
        _ScaleX ("Scale X", float) = 1.0
        _ScaleY ("Scale Y", float) = 1.0
        _Rotate ("Rotate", float) = 0.0
    }
    SubShader
    {
        Tags { "RenderType"="Transparent" "Queue"="Transparent" }
        LOD 100
        Blend SrcAlpha OneMinusSrcAlpha

        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            // make fog work
            #pragma multi_compile_fog

            #include "UnityCG.cginc"

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

            struct v2f
            {
                float2 uv : TEXCOORD0;
                UNITY_FOG_COORDS(1)
                float4 vertex : SV_POSITION;
            };

            sampler2D _MainTex;
            float4 _MainTex_ST;
            float _PositionX;
            float _PositionY;
            float _ScaleX;
            float _ScaleY;
            float _Rotate;

            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = TRANSFORM_TEX(v.uv, _MainTex);
                float2 pivot = float2 (0.5, 0.5);
                float3 uv = float3 (o.uv.x, o.uv.y, 1);
                _Rotate = _Rotate * 0.0174533;
                float3x3 posisionMatrix = {
                    1, 0, 0,
                    0, 1, 0,
                    -_PositionX, -_PositionY, 1
                };
                float3x3 scaleMatrix = {
                    1/_ScaleX, 0, 0,
                    0, 1/_ScaleY, 0,
                    0, 0, 1
                };
                float3x3 rotateMatrix = {
                    cos (_Rotate), sin (_Rotate), 0,
                    -sin (_Rotate), cos (_Rotate), 0,
                    0, 0, 1
                };
                float3 mulUV = mul (mul (mul (uv, posisionMatrix) - pivot, rotateMatrix), scaleMatrix);
                o.uv = float2 (mulUV.x, mulUV.y) + pivot;
                UNITY_TRANSFER_FOG(o,o.vertex);
                return o;
            }

            fixed4 frag (v2f i) : SV_Target
            {
                // sample the texture
                fixed4 col = tex2D(_MainTex, i.uv);
                // apply fog
                UNITY_APPLY_FOG(i.fogCoord, col);
                return col;
            }
            ENDCG
        }
    }
}