feat: prepare shader for hdrp

Resources/Shaders/DearImGui-Mesh.shader

@@ -43,4 +43,26 @@
             ENDCG
         }
     }
+
+    // shader for HD render pipeline
+    SubShader
+    {
+        Tags { "RenderType" = "Transparent" "RenderPipeline" = "HDRenderPipeline" "PreviewType" = "Plane" }
+        LOD 100
+
+        Lighting Off
+        Cull Off ZWrite On ZTest Always
+        Blend SrcAlpha OneMinusSrcAlpha
+
+        Pass
+        {
+            Name "DEARIMGUI HDRP"
+
+            HLSLPROGRAM
+            #pragma vertex ImGuiPassVertex
+            #pragma fragment ImGuiPassFrag
+            #include "./PassesHD.hlsl"
+            ENDHLSL
+        }
+    }
 }

Resources/Shaders/DearImGui-Procedural.shader

@@ -69,4 +69,26 @@
             ENDCG
         }
     }
+
+    // shader for HD render pipeline
+    SubShader
+    {
+        Tags { "RenderType" = "Transparent" "RenderPipeline" = "HDRenderPipeline" "PreviewType" = "Plane" }
+        LOD 100
+
+        Lighting Off
+        Cull Off ZWrite On ZTest Always
+        Blend SrcAlpha OneMinusSrcAlpha
+
+        Pass
+        {
+            Name "DEARIMGUI HDRP"
+
+            HLSLPROGRAM
+            #pragma vertex ImGuiPassVertex
+            #pragma fragment ImGuiPassFrag
+            #include "./PassesHD.hlsl"
+            ENDHLSL
+        }
+    }
 }

Resources/Shaders/PassesHD.hlsl

@@ -0,0 +1,37 @@
+#ifndef DEARIMGUI_HDRP_INCLUDED
+#define DEARIMGUI_HDRP_INCLUDED
+
+#include "UnityCG.cginc"
+#include "./Common.hlsl"
+
+sampler2D _Texture;
+
+half4 unpack_color(uint c)
+{
+	half4 color = half4(
+		(c) & 0xff,
+		(c >> 8) & 0xff,
+		(c >> 16) & 0xff,
+		(c >> 24) & 0xff
+		) / 255;
+#ifndef UNITY_COLORSPACE_GAMMA
+	color.rgb = GammaToLinearSpace(color.rgb);
+#endif
+	return color;
+}
+
+Varyings ImGuiPassVertex(ImVert input)
+{
+	Varyings output = (Varyings)0;
+	output.vertex = UnityObjectToClipPos(float4(input.vertex, 0, 1));
+	output.uv = float2(input.uv.x, 1 - input.uv.y);
+	output.color = unpack_color(input.color);
+	return output;
+}
+
+half4 ImGuiPassFrag(Varyings input) : SV_Target
+{
+	return input.color * tex2D(_Texture, input.uv);
+}
+
+#endif