Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °
You are not logged in.
#1 2005-11-04 12:37:23
- ray
- Novice
Offline
have a graph, looking for the function
Hi !
I am writing a 3D shader and I got this graph and I just can't figure out the function 
The result value (given in greyscale values between 0=black and 1=white) depends on the two variables a and b.
It is for example,
0.5 when a=b
1 when a=1
0 when b=1
0.5+(a/2) when b=0
0.5+(b/2) when a=0
(is there a name for this kind of graph btw.?)
I think it must be a quite simple function.
Thanks in advanced for help 
Ray
#2 2005-11-04 16:22:15
- MathsIsFun
- Administrator
Offline
Re: have a graph, looking for the function
Calculate the slope (or angle) from any point to (1,1) and base it on that.
Example: (0.2,0.2) ==> Slope = (1-0.2)/(1-0.2) = 1 = 45°
Example: (0.9,0.2) ==> Slope = (1-0.2)/(1-0.9) = 8 = 83°
So you could say the first point was 45°/90° = 0.5, and the second 83°/90° = 0.92
That should get you close.
"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman