Updated color calculus for sunsky

- removed ugly clamping function (it was dividing XYZ based on max of
  one of the values)
- added option to use Exposure, this only works for brightness (Y).
  results look very pleasant, foggy and hazy results are possible.
  with exposre==0, no exposure happens for HDR extreme range skies,
  this is how yafray rendered it.
- added menu for choosing color spaces (CIE = modern lcds)

Please review! (and yes i know it's still not in World :)

4 files changed, 20 insertions, 21 deletions

diff --git a/source/blender/render/intern/include/sunsky.h b/source/blender/render/intern/include/sunsky.h
index c5e547097d2..f61338bcf27 100644
--- a/source/blender/render/intern/include/sunsky.h
+++ b/source/blender/render/intern/include/sunsky.h
@@ -33,7 +33,7 @@
 
 typedef struct SunSky
 {
-    short effect_type, skyblendtype;
+    short effect_type, skyblendtype, sky_colorspace;
     float turbidity;
     float theta, phi;
     
@@ -54,6 +54,7 @@ typedef struct SunSky
     float sun_size;
     float backscattered_light;
     float skyblendfac;
+	float sky_exposure;
 	
     float atm_HGg;
 
@@ -86,7 +87,7 @@ typedef struct SunSky
  * */
 void InitSunSky(struct SunSky *sunsky, float turb, float *toSun, float horizon_brightness, 
 				float spread,float sun_brightness, float sun_size, float back_scatter,
-				float skyblendfac, short skyblendtype);
+				float skyblendfac, short skyblendtype, float sky_exposure, float sky_colorspace);
 
 /**
  * GetSkyXYZRadiance:
diff --git a/source/blender/render/intern/source/convertblender.c b/source/blender/render/intern/source/convertblender.c
index aba96fae1c2..4af6bf6f543 100644
--- a/source/blender/render/intern/source/convertblender.c
+++ b/source/blender/render/intern/source/convertblender.c
@@ -3528,7 +3528,7 @@ static GroupObject *add_render_lamp(Render *re, Object *ob)
 		    
 			InitSunSky(lar->sunsky, la->atm_turbidity, vec, la->horizon_brightness, 
 					la->spread, la->sun_brightness, la->sun_size, la->backscattered_light,
-					   la->skyblendfac, la->skyblendtype);
+					   la->skyblendfac, la->skyblendtype, la->sky_exposure, la->sky_colorspace);
 			
 			InitAtmosphere(lar->sunsky, la->sun_intensity, 1.0, 1.0, la->atm_inscattering_factor, la->atm_extinction_factor,
 					la->atm_distance_factor);
diff --git a/source/blender/render/intern/source/pixelshading.c b/source/blender/render/intern/source/pixelshading.c
index 9551a7b3227..a13829d0306 100644
--- a/source/blender/render/intern/source/pixelshading.c
+++ b/source/blender/render/intern/source/pixelshading.c
@@ -573,7 +573,6 @@ void shadeSkyView(float *colf, float *rco, float *view, float *dxyview)
 void shadeSunView(struct SunSky *sunsky, float *colf, float *rco, float *view, float *dxyview)
 {
 	float colorxyz[3];
-	float scale;
 			
 	/**
 	sunAngle = sqrt(sunsky->sunSolidAngle / M_PI);
@@ -588,15 +587,10 @@ void shadeSunView(struct SunSky *sunsky, float *colf, float *rco, float *view, f
 	if (view[2] < 0.0)
 		view[2] = 0.0;
 	Normalize(view);
+	
 	GetSkyXYZRadiancef(sunsky, view, colorxyz);
-	scale = MAX3(colorxyz[0], colorxyz[1], colorxyz[2]);
-	colorxyz[0] /= scale;
-	colorxyz[1] /= scale;
-	colorxyz[2] /= scale;
 	
-	xyz_to_rgb(colorxyz[0], colorxyz[1], colorxyz[2], &colf[0], &colf[1], &colf[2], BLI_CS_SMPTE);
-
-	ClipColor(colf);
+	xyz_to_rgb(colorxyz[0], colorxyz[1], colorxyz[2], &colf[0], &colf[1], &colf[2], sunsky->sky_colorspace);
 }
 
 
diff --git a/source/blender/render/intern/source/sunsky.c b/source/blender/render/intern/source/sunsky.c
index e1c7933cea1..2b490e71142 100644
--- a/source/blender/render/intern/source/sunsky.c
+++ b/source/blender/render/intern/source/sunsky.c
@@ -22,7 +22,7 @@
 #include "sunsky.h"
 #include "math.h"
 #include "BLI_arithb.h"
-
+#include "BKE_global.h"
 
 /**
  * These macros are defined for vector operations
@@ -111,15 +111,14 @@ static void DirectionToThetaPhi(float *toSun, float *theta, float *phi)
 float PerezFunction(struct SunSky *sunsky, const float *lam, float theta, float gamma, float lvz)
 {
     float den, num;
-
+	
     den = ((1 + lam[0] * exp(lam[1])) *
-                   (1 + lam[2] * exp(lam[3] * sunsky->theta) + lam[4] * cos(sunsky->theta) * cos(sunsky->theta)));
-
+		   (1 + lam[2] * exp(lam[3] * sunsky->theta) + lam[4] * cos(sunsky->theta) * cos(sunsky->theta)));
+	
     num = ((1 + lam[0] * exp(lam[1] / cos(theta))) *
-                   (1 + lam[2] * exp(lam[3] * gamma) + lam[4] * cos(gamma) * cos(gamma)));
-
-    return(lvz * num / den);
-}
+		   (1 + lam[2] * exp(lam[3] * gamma) + lam[4] * cos(gamma) * cos(gamma)));
+	
+    return(lvz * num / den);}
 
 /**
  * InitSunSky:
@@ -136,7 +135,7 @@ float PerezFunction(struct SunSky *sunsky, const float *lam, float theta, float
  * */
 void InitSunSky(struct SunSky *sunsky, float turb, float *toSun, float horizon_brightness, 
 				float spread,float sun_brightness, float sun_size, float back_scatter,
-				float skyblendfac, short skyblendtype)
+				float skyblendfac, short skyblendtype, float sky_exposure, float sky_colorspace)
 {
     
    	float theta2;
@@ -154,6 +153,8 @@ void InitSunSky(struct SunSky *sunsky, float turb, float *toSun, float horizon_b
 	sunsky->backscattered_light = back_scatter;
 	sunsky->skyblendfac= skyblendfac;
 	sunsky->skyblendtype= skyblendtype;
+	sunsky->sky_exposure= -sky_exposure;
+	sunsky->sky_colorspace= sky_colorspace;
 	
 	sunsky->toSun[0] = toSun[0];
     sunsky->toSun[1] = toSun[1];
@@ -262,8 +263,11 @@ void GetSkyXYZRadiance(struct SunSky* sunsky, float theta, float phi, float colo
     // Compute xyY values
     x = PerezFunction(sunsky, sunsky->perez_x, theta, gamma, sunsky->zenith_x);
     y = PerezFunction(sunsky, sunsky->perez_y, theta, gamma, sunsky->zenith_y);
-    Y = nfade * hfade * PerezFunction(sunsky, sunsky->perez_Y, theta, gamma, sunsky->zenith_Y);
+    Y = 6.666666667e-5 * nfade * hfade * PerezFunction(sunsky, sunsky->perez_Y, theta, gamma, sunsky->zenith_Y);
 
+	if(sunsky->sky_exposure!=0.0f)
+		Y = 1.0 - exp(Y*sunsky->sky_exposure);
+	
     X = (x / y) * Y;
     Z = ((1 - x - y) / y) * Y;