dynamic sky atmosphere updates

WickedEngine/skyHF.hlsli

@@ -25,38 +25,35 @@ float noise(in float2 p)
 	return dot(n, float3(70.0, 70.0, 70.0));
 }
 
-//#define SIMPLE_SKY
-float3 GetDynamicSkyColor(in float3 normal, bool sun_enabled = true, bool clouds_enabled = true, bool dark_enabled = false)
+// Returns sky color modulated by the sun and clouds
+//	V	: view direction
+float3 GetDynamicSkyColor(in float3 V, bool sun_enabled = true, bool clouds_enabled = true, bool dark_enabled = false)
 {
-#ifdef SIMPLE_SKY
-	const float aboveHorizon = saturate(pow(saturate(normal.y), 0.3f + g_xFrame_Fog.z) / (g_xFrame_Fog.z + 1));
-	const float3 sky = lerp(GetHorizonColor(), GetZenithColor(), smoothstep(0, 1, aboveHorizon));
-#else
 	const float3 skyColor = GetZenithColor();
 	const float3 sunDirection = GetSunDirection();
 	const float3 sunColor = GetSunColor();
+	sun_enabled = sun_enabled && any(sunColor);
 
-	const float zenith = normal.y; // how much is above (0: horizon, 1: directly above)
+	const float zenith = V.y; // how much is above (0: horizon, 1: directly above)
 	const float sunScatter = saturate(sunDirection.y + 0.1f); // how much the sun is directly above. Even if sunis at horizon, we add a constant scattering amount so that light still scatters at horizon
 
-	const float atmosphereDensity = 0.7f; // constant of air density (bigger is more obstruction of sun)
+	const float atmosphereDensity = 0.5 + g_xFrame_Fog.z; // constant of air density, or "fog height" as interpreted here (bigger is more obstruction of sun)
 	const float zenithDensity = atmosphereDensity / pow(max(0.000001f, zenith), 0.75f);
 	const float sunScatterDensity = atmosphereDensity / pow(max(0.000001f, sunScatter), 0.75f);
 
-	const float3 skyAbsorption = exp2(skyColor * -zenithDensity) * 2.0f; // gradient on horizon
-	const float3 sunAbsorption = sunColor * exp2(skyColor * -sunScatterDensity) * 2.0f; // gradient of sun when it's getting below horizon
+	const float3 aberration = float3(0.39, 0.57, 1.0); // the chromatic aberration effect on the horizon-zenith fade line
+	const float3 skyAbsorption = saturate(exp2(aberration * -zenithDensity) * 2.0f); // gradient on horizon
+	const float3 sunAbsorption = sun_enabled ? saturate(sunColor * exp2(aberration * -sunScatterDensity) * 2.0f) : 1; // gradient of sun when it's getting below horizon
 
-	const float sunAmount = distance(normal, sunDirection); // sun falloff descreasing from mid point
-	const float rayleigh = 1.0 + pow(1.0 - saturate(sunAmount), 2.0) * PI * 0.5;
+	const float sunAmount = distance(V, sunDirection); // sun falloff descreasing from mid point
+	const float rayleigh = sun_enabled ? 1.0 + pow(1.0 - saturate(sunAmount), 2.0) * PI * 0.5 : 1;
 	const float mie_disk = saturate(1.0 - pow(sunAmount, 0.1));
 	const float3 mie = mie_disk * mie_disk*(3.0 - 2.0 * mie_disk) * 2.0 * PI * sunAbsorption;
 
-	const float3 sun = smoothstep(0.03, 0.026, sunAmount) * 50.0 * skyAbsorption; // sun disc
-	const float3 horizon = GetHorizonColor() * saturate(1 - skyAbsorption); // horizon color will affect when zenith density decreases
+	const float3 sun = smoothstep(0.03, 0.026, sunAmount) * sunColor * 50.0 * skyAbsorption; // sun disc
 
-	float3 sky = skyColor * zenithDensity * rayleigh;
-	sky = lerp(sky * skyAbsorption, sky / (sky + 0.5), sunScatter); // when sun goes below horizon, absorb sky color
-	sky += horizon; // tint horizon color
+	float3 sky = lerp(GetHorizonColor(), GetZenithColor() * zenithDensity * rayleigh, skyAbsorption);
+	sky = lerp(sky * skyAbsorption, sky, sunScatter); // when sun goes below horizon, absorb sky color
 	if (sun_enabled)
 	{
 		sky += sun;
@@ -67,7 +64,7 @@ float3 GetDynamicSkyColor(in float3 normal, bool sun_enabled = true, bool clouds
 
 	if (dark_enabled)
 	{
-		sky = max(pow(saturate(dot(GetSunDirection().xyz, normal)), 64)*GetSunColor().rgb, 0) * skyAbsorption;
+		sky = max(pow(saturate(dot(GetSunDirection().xyz, V)), 64) * sunColor, 0) * skyAbsorption;
 	}
 
 	if (clouds_enabled)
@@ -79,7 +76,7 @@ float3 GetDynamicSkyColor(in float3 normal, bool sun_enabled = true, bool clouds
 
 		// Trace a cloud layer plane:
 		const float3 o = g_xCamera_CamPos;
-		const float3 d = normal;
+		const float3 d = V;
 		const float3 planeOrigin = float3(0, 1000, 0);
 		const float3 planeNormal = float3(0, -1, 0);
 		const float t = Trace_plane(o, d, planeOrigin, planeNormal);
@@ -157,8 +154,6 @@ float3 GetDynamicSkyColor(in float3 normal, bool sun_enabled = true, bool clouds
 		}
 	}
 
-#endif // SIMPLE_SKY
-
 	return sky;
 }
 

WickedEngine/wiRenderer.cpp

@@ -3550,7 +3550,7 @@ void UpdatePerFrameData(float dt, uint32_t layerMask)
 {
 	renderTime_Prev = renderTime;
 	deltaTime = dt * GetGameSpeed();
-	renderTime += dt;
+	renderTime += deltaTime;
 
 	GraphicsDevice* device = GetDevice();
 	Scene& scene = GetScene();

WickedEngine/wiSceneSystem.h

@@ -906,7 +906,7 @@ namespace wiSceneSystem
 		};
 		uint32_t _flags = EMPTY;
 
-		XMFLOAT3 sunColor = XMFLOAT3(1, 1, 1);
+		XMFLOAT3 sunColor = XMFLOAT3(0, 0, 0);
 		XMFLOAT3 sunDirection = XMFLOAT3(0, 1, 0);
 		XMFLOAT3 horizon = XMFLOAT3(0.0f, 0.0f, 0.0f);
 		XMFLOAT3 zenith = XMFLOAT3(0.0f, 0.0f, 0.0f);