the 3D lightsource challenge

Esper · **Joined:** Jul 17, 2012 **Posts:** 2769

the K1te thread made me think...
viewtopic.php?f=4&t=6359

ofnuts wrote:

Wondering how we can get reflections from a light at top left together with a drop shadow from a light at top right...

this is coming up in all 3D related stuff, getting the directions of light and shadow right

here is a trick how you can probably deal with this problem
you make a little red point, and then offset the shadow layer along the vanishing points of the lightrays

Attachment:

Light II.png [ 60.4 KiB | Viewed 1719 times ]

is there a better way of doing it ?

i think one problem is, that the offset dialog, only accepts pixel values and no angles
and another thing that bugs me, is that everytime you hit okay on the offset dialog and then re open it, the values are reset to zero

he4rty · **Joined:** Aug 30, 2012 **Posts:** 2174

Interesting topic esper, but you would also need to consider the light source coming from behind or in front of the image.

Esper · **Joined:** Jul 17, 2012 **Posts:** 2769

yes i thought about that too, but i dont know how to show that really, and what is the effect

i guess the higher the lightsource the deeper (broader) the light and shadow, right ?

anarkhya · **Posted:** Sun Feb 03, 2013 3:07 pm **(#4)**

It also depends on the distance between the object and the surface where the shadow is cast. Oh and using colored shadow instead of the usual transparent black is a plus, IIRC, the color of a shadow is the complementary color of the lightsource (it surely is more complex in nature but it's one of the basic principles it seems) besides the color of the object plays its role in the shadow color.

K1TesseraEna · **Joined:** Sep 22, 2012 **Posts:** 2089 **Location:** US

I guess, there is no better way to make a shadow from a bright distant lightsource. Your method is the best for 2d editors.
In real life source of light is not always distant and casting a linear shadows in one direction (can't be reproduced by just offsetting the shadow copy of the object).
Blender offers 5 different sources for 2 different types of light: directional (sun, hemi, area) and point (spot and point).
GIMP has two types in Lighting Effects but they are not very good for creating cast shadows.
PS6 Extended 3D has a new so called 'infinite' source, for which a drop shadow is very subtle.
By and large, the best drop shadows are created with 3d engine computations.