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Assets/Alloy/Shaders/Feature/TransitionBlend.cginc

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+// Alloy Physical Shader Framework
+// Copyright 2013-2017 RUST LLC.
+// http://www.alloy.rustltd.com/
+
+/////////////////////////////////////////////////////////////////////////////////
+/// @file TransitionBlend.cginc
+/// @brief Blending using an alpha mask and a cutoff, with a glow effect.
+/////////////////////////////////////////////////////////////////////////////////
+
+#ifndef ALLOY_SHADERS_FEATURE_TRANSITION_BLEND_CGINC
+#define ALLOY_SHADERS_FEATURE_TRANSITION_BLEND_CGINC
+
+#ifdef A_TRANSITION_BLEND_ON
+    #ifndef A_EMISSIVE_COLOR_ON
+        #define A_EMISSIVE_COLOR_ON
+    #endif
+#endif
+
+#include "Assets/Alloy/Shaders/Framework/Feature.cginc"
+
+#ifdef A_TRANSITION_BLEND_ON
+    /// Transition glow tint color.
+    /// Expects a linear HDR color with alpha.
+    half4 _TransitionGlowColor; 
+    
+    /// Transition glow color with effect ramp in the alpha.
+    /// Expects an RGBA map with sRGB sampling.
+    A_SAMPLER_2D(_TransitionTex);
+    
+    /// The cutoff value for the transition effect in the ramp map.
+    /// Expects values in the range [0,1].
+    half _TransitionCutoff;
+
+    #ifndef A_TRANSITION_BLEND_GLOW_OFF
+        /// The weight of the transition glow effect.
+        /// Expects linear space value in the range [0,1].
+        half _TransitionGlowWeight;
+    
+        /// The width of the transition glow effect.
+        /// Expects values in the range [0,1].
+        half _TransitionEdgeWidth;
+    #endif
+#endif
+
+void aTransitionBlend(
+    inout ASurface s)
+{
+#ifdef A_TRANSITION_BLEND_ON
+    float2 transitionUv = A_TEX_TRANSFORM_UV(s, _TransitionTex);
+    half4 transitionBase = _TransitionGlowColor * tex2D(_TransitionTex, transitionUv);
+    half clipval = transitionBase.a * 0.99h - _TransitionCutoff;
+
+    s.mask = clipval >= 0 ? 0.0h : s.mask;
+
+    #ifndef A_TRANSITION_BLEND_GLOW_OFF
+        // Transition glow
+        half3 glow = s.emissiveColor + transitionBase.rgb * _TransitionGlowWeight;
+
+        glow = clipval >= _TransitionEdgeWidth ? s.emissiveColor : glow; // Outer edge.
+        s.emissiveColor = _TransitionCutoff < A_EPSILON ? s.emissiveColor : glow; // Kill when cutoff is zero.
+    #endif
+#endif
+}
+
+#endif // ALLOY_SHADERS_FEATURE_TRANSITION_BLEND_CGINC