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Fractal Software => Bug Reporting => Topic started by: Kyzia on August 23, 2017, 09:18:57 PM




Title: 2.12 Alpha 6 : Fresnel's equations for reflectance not working
Post by: Kyzia on August 23, 2017, 09:18:57 PM
I wasn't sure whether to report this - figuring maybe it's not implemented yet, but then I spotted this in the 'What's new for Alpha 6'
 
Quote
Added "full" OpenCL rendering engine which allows to render fractals with reflections and transparency (refraction and Fresnel reflectance).

If I set reflectance to a non-zero value, it has an effect on the output, but if I then tick 'Fresnel's equations for reflectance', the image reverts to having no reflection effect (equivalent to setting reflectance value back to 0)

This is while using OpenCL on my system with Nvidia graphics card.


Title: Re: 2.12 Alpha 6 : Fresnel's equations for reflectance not working
Post by: Buddhi on August 23, 2017, 09:40:54 PM
Try these settings

Code:
# Mandelbulber settings file
# version 2.11
# only modified parameters
[main_parameters]
camera 0,02153492350061934 -0,5781767204978938 -0,01308977637211101;
camera_distance_to_target 1,006371531377792;
camera_rotation 14,53326968527237 -21,29487963383603 -7,583282522633771;
camera_top -0,2180815913931096 0,3153566243596848 0,9235749124829634;
detail_level 0,239883;
DOF_focus 0,9860317707061768;
DOF_radius 39,56;
flight_last_to_render 0;
formula_1 7;
keyframe_last_to_render 0;
mat1_coloring_palette_offset 8,210000000000001;
mat1_fresnel_reflectance true;
mat1_is_defined true;
mat1_reflectance 1;
raytraced_reflections true;
reflections_max 1;
target -0,2137635243121594 0,3294803064774741 -0,378571678806166;
[fractal_1]
IFS_rotation_enabled true;
[fractal_2]
IFS_rotation_enabled true;
[fractal_3]
IFS_rotation_enabled true;
[fractal_4]
IFS_rotation_enabled true;

When Fresnel reflectance is enabled, reflections are only slightly visible. But try to increase index of refraction (in physics it's equivalent to increase of density of the material), then you will see that reflections are more visible.

By the way read this to learn about Fresnel equations: https://en.wikipedia.org/wiki/Fresnel_equations