Cycles / Sky Model:

* Replaced the Preetham model with the newer Hosek / Wilkie model:
"An Analytic Model for Full Spectral Sky-Dome Radiance" http://cgg.mff.cuni.cz/projects/SkylightModelling/ 

* We use the sample code data, which comes with the paper, but removed some unnecessary parts, we only need the xyz version.
* New "Albedo" UI paraemeter, to control the ground albedo (between 0 and 1). 
* Works with SVM only atm (CPU and CUDA). 

Example render:
http://www.pasteall.org/pic/show.php?id=57635

ToDo / Open Questions:
* OSL still uses the old model, will be done later. In the meantime it's useful to compare the two models this way.
* The new model needs a much weaker Strength value (0.01), otherwise it's white. Can this be fixed? 
* Code cleanup. 

1 files changed, 3 insertions, 4 deletions

diff --git a/intern/cycles/kernel/kernel_types.h b/intern/cycles/kernel/kernel_types.h
index 836eacf7cb6..69a3a4fe28c 100644
--- a/intern/cycles/kernel/kernel_types.h
+++ b/intern/cycles/kernel/kernel_types.h
@@ -718,12 +718,11 @@ typedef struct KernelBackground {
 
 typedef struct KernelSunSky {
 	/* sun direction in spherical and cartesian */
-	float theta, phi, pad3, pad4;
+	float theta, phi;
 
 	/* perez function parameters */
-	float zenith_Y, zenith_x, zenith_y, pad2;
-	float perez_Y[5], perez_x[5], perez_y[5];
-	float pad5;
+	float radiance_x, radiance_y, radiance_z;
+	float config_x[9], config_y[9], config_z[9];
 } KernelSunSky;
 
 typedef struct KernelIntegrator {