Question about the alpha slider. I understand the alpha ramps & what they do, just not totally sure what that slider does other than increase performance by as explain in original release thread "Ramps are displayed with less surfaces then".
Less surfaces? can somebody give me or point me to a better explanation on the "less surfaces" thing?
I took screenshots of a big alpha ramp at slider all the way left, right, & center. & visually it all looked the same, & the ball had the same amount of transparency underneath them.
So really I'm just wondering what the visual drawback is of cranking the slider left.
Cupid could give you a better answer - I think he heavily optimized the slider so that the far left takes fewer system resources by drawing the ramp in fewer pieces. This results in a ramp that isn't as perfectly mathematically 'smoothed' as a ramp with more parts would be (the slider pushed to the right). You might try making a ramp that is 500 vp units wide at the bottom and 60 units wide at the top, with a bunch of curves in it to see a difference.
Destruk is right.
Consider an easy ramp with 4 control points and no borders, where control points not in a line and the ramp has a legth of over 400 units.
With the slider to the left, the ramp has 12 triangles, 4 real control points and 3 virtual control points.
With the slider to the right, the ramp will have over 1000 triangles (maybe much more or some less, but MANY more than 12), 4 real control points and many virtual control points.
If the ramp has sides, multiply that values by 3.
You can only see this at the left and right edge of the ramp. It will have edges instead of curves, if you set the alpha ramp accuracy low.
Between the control points, a spline curve is calculated.
shows the difference between linear and spline interpolation.
The more the slider is set to left, the more the ramp it is linear interpolated and need less triagles at runtime to display. Slider to the right interpolates more and more with a furmula called Catmul-Rom described here:
http://www.mvps.org/...ticles/catmull/ .
3d Programs like Blender, maya, 3ds-max have better functions for this, and professional games always have low-poly Objects. In
VP, this is not possible, since we have to calculate the points in 3d space in real time or during the compilation of the table (when you hit play).
Now why don't you see any difference? JP did set some more control points as needed. Of course the ramp has more triangles then, but like this, the ramp is optimized already for the slider beeing all the way to the left. In curves, he did set some more points; on long straigt lines, he did set less.
Cupid
Edited by cupid, 26 February 2011 - 08:40 PM.
Get better soon man.
From Brasil. Updated version of 1234fd
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