need help with Cinema4D fresnel

[OnoSendai]

Code: Select all

	<material>
		<name>mat1</name>
		
		<diffuse>
			<texture>
				<path>blackrose_pattern.jpg</path>
				<uv_set>default</uv_set>
				<exponent>2.2</exponent>
			</texture>
			
			<texture>
				<path>../italy_bolsena_flag_flowers_stairs_01.jpg</path>
				<uv_set>default</uv_set>
				<exponent>2.2</exponent>
			</texture>
			
			<albedo>
				<shader>
					<shader>
						<![CDATA[     
def eval(vec3 pos) vec3 :
  let 
    uv = getTexCoords(0)
  in
    lerp(
      sample2DTextureVec3(0, uv),
      sample2DTextureVec3(1, uv),
      minCosTheta()
    )
						]]>
					</shader>
				</shader>
			</albedo>
			<random_triangle_colours>false</random_triangle_colours>
			<layer>0</layer>
		</diffuse>
	</material>

[N.G.]

what did I do wrong?

<material>
<name>mat1</name>

<diffuse>
<texture>
<path>L:\Indigo\tex\14_5_17_d.jpg</path>
<uv_set>default</uv_set>
<exponent>2.2</exponent>
</texture>

<texture>
<path>L:\Indigo\tex\14_5_15_b.jpg</path>
<uv_set>default</uv_set>
<exponent>2.2</exponent>
</texture>

<albedo>
<shader>
<shader>
<![CDATA[
def eval(vec3 pos) vec3 :
let
uv = getTexCoords(0)
in
lerp(
sample2DTextureVec3(0, uv),
sample2DTextureVec3(1, uv),
minCosTheta()
)
]]>
</shader>
</shader>
</albedo>
<random_triangle_colours>false</random_triangle_colours>
<layer>0</layer>
</diffuse>
</material>

[Zom-B]

what did I do wrong?

You've put IGS code into the ISL Editor


Only put that code into the editor:

Code: Select all

def eval(vec3 pos) vec3 :
  let
    uv = getTexCoords(0)
  in
    lerp(
      sample2DTextureVec3(0, uv),
      sample2DTextureVec3(1, uv),
      minCosTheta()
    )

Now define two textures in the first both fields above the Code window.


The Problem about minCosTheta Ono is that the result isn't fresnel but something else...

[N.G.]

honestly, I realized that nothing I do not understand anything. I need an example. Please give me your shader.

when I see program code-brain off.

[Zom-B]

Here you go:

[N.G.]

Here you go:

I love you!

it works!

[N.G.]

YES.

minCosTheta Ono is that the result isn't fresnel but something else...

[fused]

While it looks like it will just work like that, as soon as you add any other texture to that material, it will break.

Unfortunately, due to the way Indigo's material system works, referenceing textures in ISL shaders is a bit tricky (referencing is actually easy, maintaining the reference after changes to materials is where it gets annoying).

In Cindigo, you can work around that by using the placeholders specified in the label of the texture file selector ($tex01$, $tex02$, $tex03$).
It's lame, but works.

These placeholders will be replaced with the id the texture actually has on rendering.

your ISL code should look like this:

Code: Select all

def eval(vec3 pos) vec3 :
  let 
    uv = getTexCoords(0)
  in
    lerp(
      sample2DTextureVec3($tex01$, uv),
      sample2DTextureVec3($tex02$, uv),
      minCosTheta()
    )

[galinette]

YES.

minCosTheta Ono is that the result isn't fresnel but something else...

For fresnel, as told before, you can try:

1.0 - pow(1.0 - (2.0/(1.0/maxCosTheta() + 1.0/minCosTheta())), 5.0)

or

1.0 - pow(1.0 - (0.5*(maxCosTheta() + minCosTheta()), 5.0)


However, none is 100% identical to the one used in most softwares, which use the cosineTheta of the halfway vector, which is not available in Indigo (subliminal message to Ono )

If this was available, you would use :
1.0 - pow(1.0 - cosThetaHalfway(), 5.0)

[N.G.]

Why should I to score a head program codes? need to make everything easier!!
THANK YOU ALL!

[OnoSendai]

However, none is 100% identical to the one used in most softwares, which use the cosineTheta of the halfway vector, which is not available in Indigo (subliminal message to Ono )

Good idea

[wlf_alex]

Thank you guys! You are Superman!

[Zom-B]

Thanks for the code galinette, its better then pure minCosTheta().

I attached example of fresnel vs ISL

1.0 - pow(1.0 - (2.0/(1.0/maxCosTheta() + 1.0/minCosTheta())), 5.0)

or

1.0 - pow(1.0 - (0.5*(maxCosTheta() + minCosTheta()), 5.0)

The bottom example misses a )

Why should I to score a head program codes? need to make everything easier!!
THANK YOU ALL!

Its NOT about coding at all here, JUST the knowledge what values to EDIT!!
I also don't understand ISL code at all!!!!

here is the code I used for the example, the bold number is the strength of fresnel, value of 1,75 seems to be a good start.

def eval(vec3 pos) vec3 :
let
uv = getTexCoords(0)
in
lerp(
sample2DTextureVec3(0, uv),
sample2DTextureVec3(1, uv),
1.0 - pow(1.0 - (0.5*(maxCosTheta() + minCosTheta())), 1.75)
)

I attached also a example with value of 3 just to show you the result.

However, none is 100% identical to the one used in most softwares, which use the cosineTheta of the halfway vector, which is not available in Indigo (subliminal message to Ono )

Good idea

Would be sweeeeeet!!!

[wlf_alex]

Thanks a lot Zom-B !!!

[galinette]

Zom-B : which refractive index are you using in the C4D shader?

Etienne