149 lines
6.2 KiB
Plaintext
149 lines
6.2 KiB
Plaintext
Shader "IndianOcean/SpriteEchoOutline"
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{
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// 回声描边 Shader —— 配合 EchoSystem 使用
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// 渲染精灵的"外描边"，颜色默认白色（可自定义），由全局回声参数控制显隐。
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// 渲染队列在黑暗遮罩（Transparent+100）之上（Transparent+200），
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// 所以即使在黑暗中（黑暗遮罩把场景乘成纯黑），描边依然可见。
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//
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// 工作原理：
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// - 顶点着色器：以精灵中心为基准向外扩展顶点，为外描边腾出空间
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// - 片元着色器：8 方向膨胀采样精灵 alpha，邻居有 alpha 但中心没有 → 描边像素
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// - 回声控制：精灵世界坐标距 _EchoCenter 小于 _EchoRadius 才显示描边
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Properties
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{
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_MainTex ("Sprite Texture", 2D) = "white" {}
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_OutlineColor ("描边颜色（乘以全局回声颜色，默认白）", Color) = (1,1,1,1)
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_OutlineWidth ("描边宽度（像素/纹素）", Range(0, 8)) = 2.0
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}
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SubShader
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{
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Tags
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{
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"RenderType" = "Transparent"
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"Queue" = "Transparent+200"
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"RenderPipeline" = "UniversalPipeline"
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}
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// 普通半透明叠加（在黑暗遮罩之后渲染，所以不被黑暗乘掉）
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Blend SrcAlpha OneMinusSrcAlpha
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ZWrite Off
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Cull Off
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Pass
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{
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Name "EchoOutline"
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HLSLPROGRAM
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#pragma vertex vert
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#pragma fragment frag
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#pragma multi_compile_instancing
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#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
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struct Attributes
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{
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float4 positionOS : POSITION;
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float2 uv : TEXCOORD0;
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UNITY_VERTEX_INPUT_INSTANCE_ID
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};
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struct Varyings
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{
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float4 positionCS : SV_POSITION;
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float2 uv : TEXCOORD0;
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float3 worldPos : TEXCOORD1;
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UNITY_VERTEX_INPUT_INSTANCE_ID
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};
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CBUFFER_START(UnityPerMaterial)
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float4 _OutlineColor;
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float _OutlineWidth;
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float4 _MainTex_ST;
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CBUFFER_END
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TEXTURE2D(_MainTex);
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SAMPLER(sampler_MainTex);
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float4 _MainTex_TexelSize;
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// 全局回声参数（由 EchoSystem 通过 Shader.SetGlobalX 设置，不是材质属性）
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float4 _EchoCenter; // xy = 回声中心世界坐标 XZ
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float _EchoRadius; // 当前波纹前沿半径
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float _EchoWidth; // 波纹前沿柔和宽度
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float _EchoOutlineIntensity; // 整体描边强度（维持=1, 消散=1→0, 关闭=0）
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float4 _EchoOutlineColor; // 全局描边颜色（默认白色）
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// 8 方向采样偏移（对角线用 0.7071 保持等距）
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static const float2 _Offsets[8] = {
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float2( 1.0, 0.0), float2(-1.0, 0.0), float2( 0.0, 1.0), float2( 0.0, -1.0),
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float2( 0.7071, 0.7071), float2(-0.7071, 0.7071),
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float2( 0.7071, -0.7071), float2(-0.7071, -0.7071)
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};
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// 带边界检查的 alpha 采样：UV 超出 [0,1] 视为空（0），避免边缘错误填充
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float sampleAlphaBounded(float2 uv)
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{
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float a = SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, uv).a;
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float inBounds = step(0.0, uv.x) * step(uv.x, 1.0)
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* step(0.0, uv.y) * step(uv.y, 1.0);
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return a * inBounds;
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}
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Varyings vert(Attributes input)
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{
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Varyings output;
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UNITY_SETUP_INSTANCE_ID(input);
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UNITY_TRANSFER_INSTANCE_ID(input, output);
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float3 posOS = input.positionOS.xyz;
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output.positionCS = TransformObjectToHClip(posOS);
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output.uv = TRANSFORM_TEX(input.uv, _MainTex);
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output.worldPos = TransformObjectToWorld(posOS);
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// 以精灵中心为基准向外扩展顶点，为外描边腾出屏幕空间
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float4 centerCS = TransformObjectToHClip(float3(0,0,0));
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float2 csDir = output.positionCS.xy - centerCS.xy;
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float len = length(csDir);
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csDir = (len > 0.0001) ? csDir / len : float2(1.0, 0.0);
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float2 ndcPerPixel = 2.0 / _ScreenParams.xy;
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output.positionCS.xy += csDir * ndcPerPixel * _OutlineWidth;
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return output;
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}
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half4 frag(Varyings input) : SV_Target
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{
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// ===== 回声距离检查 =====
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// 波纹前沿在 _EchoRadius；精灵距中心小于半径 → 已被扫描 → 显示描边
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float2 wp = input.worldPos.xz;
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float ed = distance(wp, _EchoCenter.xy);
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// smoothstep: 距离从 (radius-width) 到 radius 时从1降到0；取反 = 半径内为1
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float reached = 1.0 - smoothstep(_EchoRadius - _EchoWidth, _EchoRadius, ed);
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float intensity = reached * _EchoOutlineIntensity;
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// 回声未到达或已关闭 → 直接丢弃，零开销
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if (intensity < 0.001) discard;
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// ===== 膨胀采样得到描边 =====
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float2 uv = input.uv;
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float origAlpha = sampleAlphaBounded(uv);
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float2 texel = _MainTex_TexelSize.xy;
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float w = max(1.0, _OutlineWidth);
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float dilatedAlpha = 0.0;
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[unroll]
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for (int i = 0; i < 8; i++)
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{
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float2 ouv = uv + _Offsets[i] * texel * w;
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dilatedAlpha = max(dilatedAlpha, sampleAlphaBounded(ouv));
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}
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// 描边 = 邻居有 alpha 但中心没有（外描边）
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float outline = step(0.5, dilatedAlpha) * (1.0 - step(0.5, origAlpha));
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// ===== 输出 =====
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float3 col = _EchoOutlineColor.rgb * _OutlineColor.rgb;
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float alpha = outline * intensity * _EchoOutlineColor.a * _OutlineColor.a;
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return half4(col, alpha);
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}
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ENDHLSL
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}
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}
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FallBack Off
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}
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