Gradient Incident Angle Confusion

Gradient Incident Angle Confusion

Post by edde » Mon, 07 Jul 2003 18:23:15



I notice that in Newteks tutorial section for surfacing, they say the
following:

"The effect that this gradient will have is basically 0% reflection when
looking perfectly level at the object (0 degrees glancing angle), going to
100% reflective at any part of the object that is viewed at an angle of 90
degrees from the same point - in other words, the front bit of the sphere
that I am looking straight at will appear absolutely 0% reflective, while
the very edges of it will be 100% reflective."
(http://www.newtek.com/products/lightwave/tutorials/surface/texturing_...
mmies_004/index3.html)

However, in my tests, I get the exact opposite. 0 degrees = side surface, 90
degrees = straight on surface.

To further complicate things, I notice that the Fast Fresnel shader uses 0
degrees = straight on surface
, 90 degrees = side surface

What do others get?

 
 
 

Gradient Incident Angle Confusion

Post by Comcast News Serve » Tue, 08 Jul 2003 01:13:40


You need to invert your gradient to get it to work. Make the white part
(100% value) of the gradient black, and the black part (0% value) white.


Quote:> I notice that in Newteks tutorial section for surfacing, they say the
> following:

> "The effect that this gradient will have is basically 0% reflection when
> looking perfectly level at the object (0 degrees glancing angle), going to
> 100% reflective at any part of the object that is viewed at an angle of 90
> degrees from the same point - in other words, the front bit of the sphere
> that I am looking straight at will appear absolutely 0% reflective, while
> the very edges of it will be 100% reflective."

(http://www.newtek.com/products/lightwave/tutorials/surface/texturing_...
Quote:> mmies_004/index3.html)

> However, in my tests, I get the exact opposite. 0 degrees = side surface,
90
> degrees = straight on surface.

> To further complicate things, I notice that the Fast Fresnel shader uses 0
> degrees = straight on surface
> , 90 degrees = side surface

> What do others get?


 
 
 

Gradient Incident Angle Confusion

Post by edde » Tue, 08 Jul 2003 17:07:36


So, you would agree that the Newtek tutorial is wrong too?



> You need to invert your gradient to get it to work. Make the white part
> (100% value) of the gradient black, and the black part (0% value) white.



> > I notice that in Newteks tutorial section for surfacing, they say the
> > following:

> > "The effect that this gradient will have is basically 0% reflection when
> > looking perfectly level at the object (0 degrees glancing angle), going
to
> > 100% reflective at any part of the object that is viewed at an angle of
90
> > degrees from the same point - in other words, the front bit of the
sphere
> > that I am looking straight at will appear absolutely 0% reflective,
while
> > the very edges of it will be 100% reflective."

(http://www.newtek.com/products/lightwave/tutorials/surface/texturing_...

- Show quoted text -

Quote:> > mmies_004/index3.html)

> > However, in my tests, I get the exact opposite. 0 degrees = side
surface,
> 90
> > degrees = straight on surface.

> > To further complicate things, I notice that the Fast Fresnel shader uses
0
> > degrees = straight on surface
> > , 90 degrees = side surface

> > What do others get?

 
 
 

1. linear gradient shading with arbitray angles

Hi,

I wan't to fill rectangles with a linear gradient shading.
for the angles n*pi/2 = n*90 it is easy
calculate the rgb difference/number of lines,
draw line by line and change the color by the rgb-difference * 1/m

But how can optain fast gradients with arbitray angles?

Tobia

2. Rending Resolutino - RDS5

3. AOL Advertising Incident Not An Accident

4. Flash Designers Wanted

5. CANADA TUBES:

6. Incident

7. Tseng ADI for 3D Studio wanted

8. CCW euler angles to CW euler angles

9. euler angles to axis/angle

10. Axis Angle To Euler Angles

11. Angle rotation relative to current view angle

12. Euler angles --> Angle axis vector