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need help with Cinema4D fresnel
Posted: Wed Apr 10, 2013 4:11 am
by N.G.
How do I mix the materials through a Fresnel map?
need help with Cinema4D fresnel
Posted: Wed Apr 10, 2013 7:32 am
by zeitmeister
The C4D fresnel shader isn't supported.
Perhaps you can search this forum about fresnel; there is an effect with ISL you can use.
Re: need help with Cinema4D fresnel
Posted: Wed Apr 10, 2013 8:10 am
by wlf_alex
Who can show an example of how to use this effect in 4D?
Re: need help with Cinema4D fresnel
Posted: Wed Apr 10, 2013 10:11 am
by Mor4us
Code: Select all
def eval(vec3 pos) vec3 :
lerp(
vec3(0, 0, 0),
vec3(1.0, 1.0, 1.0),
maxCosTheta()
)
filled in an ISL Shader should do the trick
the both vec3() are the fresnel colors as rgb (1.0=255)
you can now blend your ISL Shader via "ISL Blend Shader" with the desired map or shader of your choice
best regards
Re: need help with Cinema4D fresnel
Posted: Wed Apr 10, 2013 10:48 am
by wlf_alex
Many thanks, Mor4us! This topic really has been confirmed and you will do it again. It's really simple
But now another question. Is it possible to just mix the textures?
regards..
Re: need help with Cinema4D fresnel
Posted: Wed Apr 10, 2013 8:34 pm
by N.G.
How to fix error?
Re: need help with Cinema4D fresnel
Posted: Wed Apr 10, 2013 10:55 pm
by N.G.
why so difficult?
Re: need help with Cinema4D fresnel
Posted: Wed Apr 10, 2013 11:17 pm
by galinette
Hi NG,
I think minCosTheta and maxCosTheta cannot be used in a blend shader for physical reasons (it's then easy to break energy conservation). Also, you are using a color shader (returning a RGB vec3) in a blend shader slot (which must return a single number). Both are triggering errors.
So you should not use a blend material for this. Just use a diffuse or phong material, and use the shader in the diffuse channel.
For red/blue just use:
Code: Select all
def eval(vec3 pos) vec3 :
lerp(
vec3(1.0, 0, 0),
vec3(0, 0, 1.0),
maxCosTheta() )
Also, you could use minCosTheta instead of maxCosTheta, the effect will be slightly different.
I personally use 1.0 - pow(1.0 - (2.0/(1.0/maxCosTheta() + 1.0/minCosTheta())), 5.0) as the lerp function
Etienne
Re: need help with Cinema4D fresnel
Posted: Wed Apr 10, 2013 11:34 pm
by N.G.
galinette wrote:Hi NG,
I think minCosTheta and maxCosTheta cannot be used in a blend shader for physical reasons (it's then easy to break energy conservation). Also, you are using a color shader (returning a RGB vec3) in a blend shader slot (which must return a single number). Both are triggering errors.
So you should not use a blend material for this. Just use a diffuse or phong material, and use the shader in the diffuse channel.
For red/blue just use:
Code: Select all
def eval(vec3 pos) vec3 :
lerp(
vec3(1.0, 0, 0),
vec3(0, 0, 1.0),
maxCosTheta() )
Also, you could use minCosTheta instead of maxCosTheta, the effect will be slightly different.
I personally use 1.0 - pow(1.0 - (2.0/(1.0/maxCosTheta() + 1.0/minCosTheta())), 5.0) as the lerp function
Etienne
how can I mix the two textures then? I'm confused.
Re: need help with Cinema4D fresnel
Posted: Thu Apr 11, 2013 12:03 am
by N.G.
remains impossible to blend the two textures through Fresnel falloff, or error, or the effect is not the same.
Re: need help with Cinema4D fresnel
Posted: Thu Apr 11, 2013 12:59 am
by Zom-B
N.G. wrote:remains impossible to blend the two textures through Fresnel falloff, or error, or the effect is not the same.
exactly!
Re: need help with Cinema4D fresnel
Posted: Thu Apr 11, 2013 1:11 am
by N.G.
me sad.
Re: need help with Cinema4D fresnel
Posted: Thu Apr 11, 2013 1:23 am
by OnoSendai
It's possible, just requires some ISL.
Re: need help with Cinema4D fresnel
Posted: Thu Apr 11, 2013 1:27 am
by N.G.
OnoSendai wrote:It's possible, just requires some ISL.
Can you give an example? very need
Re: need help with Cinema4D fresnel
Posted: Thu Apr 11, 2013 1:30 am
by wlf_alex
N.G. wrote:OnoSendai wrote:It's possible, just requires some ISL.
Can you give an example? very need
+10
pls-pls-pls !!!