Smooth radial gradient

Question

So, I'm trying to create a radial gradient (for static lighting in a game). I came up with this:

int step = 4;
int forLen = (radius / step);
g.setColor(new Color(0, 0, 0, intensity));
for (int i = 0; i < forLen; i++)
    g.fillOval(radius - i * step, radius - i * step, i * step * 2, i * step * 2);

But the result i get is this:

enter image description here

I'd like to get a smoother gradient, like:

enter image description here

I tried playing around with the step and the intensity, but i can't get something similar to the gradient above. What would be a good way of doing this?? Thanks in advance!

Could the problem be that you are drawing each new circle on top of an older one, thus causing the alpha to "stack" and increase much faster? — Jacob Raihle, Jun 19 '13 at 14:58
At second glance, that seems to be what you're actually trying to accomplish since you're working with a constant alpha, nvm... — Jacob Raihle, Jun 19 '13 at 15:00

score 2 · Accepted Answer · answered Jun 19 '13 at 14:54

2

I don't have a concrete answer, but the look of the second picture left me the impression that the intensity is not decreasing linearly, but rather exponentially.

Could you try instead of doing a linear decreasing function, use a exponential function instead? For every step outwards, multiply the intensity with a fixed number a < 1.

answered Jun 19 '13 at 14:54

zw324

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Maybe not exactly exponentially, but most likely superlinearly. – G. Bach Jun 19 '13 at 15:04
1

Thanks! ...i took your answer and decide to use it, but in the opposite way. I started from the outer circle, going inwards. With a really low starting intensity (0.01 for example) i multiplied it with a fixed number > 1 (1.02 for example), and that gave me the exact result i wanted, and a lot more control! – Sylar Jun 19 '13 at 15:34
@Sylar Great I could help, the way you are using is quite interesting:) – zw324 Jun 19 '13 at 15:40

Smooth radial gradient

1 Answers1