Blender 2.9 LTS support

Shaders/std/sky.glsl

@@ -0,0 +1,163 @@
+/* Various sky functions
+ * =====================
+ *
+ * Nishita model is based on https://github.com/wwwtyro/glsl-atmosphere (Unlicense License)
+ *
+ *   Changes to the original implementation:
+ *     - r and pSun parameters of nishita_atmosphere() are already normalized
+ *     - Some original parameters of nishita_atmosphere() are replaced with pre-defined values
+ *     - Implemented air, dust and ozone density node parameters (see Blender source)
+ *     - Replaced the inner integral calculation with a LUT lookup
+ *
+ * Reference for the sun's limb darkening and ozone calculations:
+ * [Hill] Sebastien Hillaire. Physically Based Sky, Atmosphere and Cloud Rendering in Frostbite
+ * (https://media.contentapi.ea.com/content/dam/eacom/frostbite/files/s2016-pbs-frostbite-sky-clouds-new.pdf)
+ *
+ * Cycles code used for reference: blender/intern/sky/source/sky_nishita.cpp
+ * (https://github.com/blender/blender/blob/4429b4b77ef6754739a3c2b4fabd0537999e9bdc/intern/sky/source/sky_nishita.cpp)
+ */
+
+#ifndef _SKY_GLSL_
+#define _SKY_GLSL_
+
+uniform sampler2D nishitaLUT;
+uniform vec2 nishitaDensity;
+
+#ifndef PI
+	#define PI 3.141592
+#endif
+#ifndef HALF_PI
+	#define HALF_PI 1.570796
+#endif
+
+#define nishita_iSteps 16
+
+// These values are taken from Cycles code if they
+// exist there, otherwise they are taken from the example
+// in the glsl-atmosphere repo
+#define nishita_sun_intensity 22.0
+#define nishita_atmo_radius 6420e3
+#define nishita_rayleigh_scale 8e3
+#define nishita_rayleigh_coeff vec3(5.5e-6, 13.0e-6, 22.4e-6)
+#define nishita_mie_scale 1.2e3
+#define nishita_mie_coeff 2e-5
+#define nishita_mie_dir 0.76 // Aerosols anisotropy ("direction")
+#define nishita_mie_dir_sq 0.5776 // Squared aerosols anisotropy
+
+// The ozone absorption coefficients are taken from Cycles code.
+// Because Cycles calculates 21 wavelengths, we use the coefficients
+// which are closest to the RGB wavelengths (645nm, 510nm, 440nm).
+// Precalculating values by simulating Blender's spec_to_xyz() function
+// to include all 21 wavelengths gave unrealistic results
+#define nishita_ozone_coeff vec3(1.59051840791988e-6, 0.00000096707041180970, 0.00000007309568762914)
+
+// Values from [Hill: 60]
+#define sun_limb_darkening_col vec3(0.397, 0.503, 0.652)
+
+float random(vec2 coords) {
+	return fract(sin(dot(coords.xy, vec2(12.9898,78.233))) * 43758.5453);
+}
+
+vec3 nishita_lookupLUT(const float height, const float sunTheta) {
+	vec2 coords = vec2(
+	sqrt(height * (1 / nishita_atmo_radius)),
+		0.5 + 0.5 * sign(sunTheta - HALF_PI) * sqrt(abs(sunTheta * (1 / HALF_PI) - 1))
+	);
+	return textureLod(nishitaLUT, coords, 0.0).rgb;
+}
+
+/* See raySphereIntersection() in armory/Sources/renderpath/Nishita.hx */
+vec2 nishita_rsi(const vec3 r0, const vec3 rd, const float sr) {
+	float a = dot(rd, rd);
+	float b = 2.0 * dot(rd, r0);
+	float c = dot(r0, r0) - (sr * sr);
+	float d = (b*b) - 4.0*a*c;
+
+	// If d < 0.0 the ray does not intersect the sphere
+	return (d < 0.0) ? vec2(1e5,-1e5) : vec2((-b - sqrt(d))/(2.0*a), (-b + sqrt(d))/(2.0*a));
+}
+
+/*
+ * r: normalized ray direction
+ * r0: ray origin
+ * pSun: normalized sun direction
+ * rPlanet: planet radius
+ */
+vec3 nishita_atmosphere(const vec3 r, const vec3 r0, const vec3 pSun, const float rPlanet) {
+	// Calculate the step size of the primary ray
+	vec2 p = nishita_rsi(r0, r, nishita_atmo_radius);
+	if (p.x > p.y) return vec3(0.0);
+	p.y = min(p.y, nishita_rsi(r0, r, rPlanet).x);
+	float iStepSize = (p.y - p.x) / float(nishita_iSteps);
+
+	// Primary ray time
+	float iTime = 0.0;
+
+	// Accumulators for Rayleigh and Mie scattering.
+	vec3 totalRlh = vec3(0,0,0);
+	vec3 totalMie = vec3(0,0,0);
+
+	// Optical depth accumulators for the primary ray
+	float iOdRlh = 0.0;
+	float iOdMie = 0.0;
+
+	// Calculate the Rayleigh and Mie phases
+	float mu = dot(r, pSun);
+	float mumu = mu * mu;
+	float pRlh = 3.0 / (16.0 * PI) * (1.0 + mumu);
+	float pMie = 3.0 / (8.0 * PI) * ((1.0 - nishita_mie_dir_sq) * (mumu + 1.0)) / (pow(1.0 + nishita_mie_dir_sq - 2.0 * mu * nishita_mie_dir, 1.5) * (2.0 + nishita_mie_dir_sq));
+
+	// Sample the primary ray
+	for (int i = 0; i < nishita_iSteps; i++) {
+
+		// Calculate the primary ray sample position and height
+		vec3 iPos = r0 + r * (iTime + iStepSize * 0.5);
+		float iHeight = length(iPos) - rPlanet;
+
+		// Calculate the optical depth of the Rayleigh and Mie scattering for this step
+		float odStepRlh = exp(-iHeight / nishita_rayleigh_scale) * nishitaDensity.x * iStepSize;
+		float odStepMie = exp(-iHeight / nishita_mie_scale) * nishitaDensity.y * iStepSize;
+
+		// Accumulate optical depth
+		iOdRlh += odStepRlh;
+		iOdMie += odStepMie;
+
+		// Idea behind this: "Rotate" everything by iPos (-> iPos is the new zenith) and then all calculations for the
+		// inner integral only depend on the sample height (iHeight) and sunTheta (angle between sun and new zenith).
+		float sunTheta = acos(dot(normalize(iPos), normalize(pSun)));
+		vec3 jODepth = nishita_lookupLUT(iHeight, sunTheta);// * vec3(14000000 / 255, 14000000 / 255, 2000000 / 255);
+
+		// Apply dithering to reduce visible banding
+		jODepth += mix(-1000, 1000, random(r.xy));
+
+		// Calculate attenuation
+		vec3 attn = exp(-(
+			nishita_mie_coeff * (iOdMie + jODepth.y)
+			+ (nishita_rayleigh_coeff) * (iOdRlh + jODepth.x)
+			+ nishita_ozone_coeff * jODepth.z
+		));
+
+		// Accumulate scattering
+		totalRlh += odStepRlh * attn;
+		totalMie += odStepMie * attn;
+
+		iTime += iStepSize;
+	}
+
+	return nishita_sun_intensity * (pRlh * nishita_rayleigh_coeff * totalRlh + pMie * nishita_mie_coeff * totalMie);
+}
+
+vec3 sun_disk(const vec3 n, const vec3 light_dir, const float disk_size, const float intensity) {
+	// Normalized SDF
+	float dist = distance(n, light_dir) / disk_size;
+
+	// Darken the edges of the sun
+	// [Hill: 28, 60] (according to [Nec96])
+	float invDist = 1.0 - dist;
+	float mu = sqrt(invDist * invDist);
+	vec3 limb_darkening = 1.0 - (1.0 - pow(vec3(mu), sun_limb_darkening_col));
+
+	return 1 + (1.0 - step(1.0, dist)) * nishita_sun_intensity * intensity * limb_darkening;
+}
+
+#endif

Sources/armory/math/Helper.hx

@@ -72,4 +72,13 @@ class Helper {
 		if (value <= leftMin) return rightMin;
 		return map(value, leftMin, leftMax, rightMin, rightMax);
 	}
+
+	/**
+		Return the sign of the given value represented as `1.0` (positive value)
+		or `-1.0` (negative value). The sign of `0` is `0`.
+	**/
+	public static inline function sign(value: Float): Float {
+		if (value == 0) return 0;
+		return (value < 0) ? -1.0 : 1.0;
+	}
 }