Lowest value on menu sliders is not 0 at first with arrows

[unknownna]

When using the left arrow key to move a slider to its lowest value, it first sets the value to some different number like 7.45058e-10, then sets it properly to 0 when you use left arrow key again, so you have to use left arrow key one extra time when it's at 0 to really set it to 0. I noticed this while using the "crosshairscale" slider in a Git build, wondering why the crosshair didn't appear at first when I turned the scaling down to 0.00.

[Graf Zahl]

Welcome to the joy that's called floating point math.

[unknownna]

This also affects GZDoom's vid_brightness "Brightness" slider when setting it back to 0 in the middle of the slider.

[Rachael]

Not sure if there's any real way to fix this outside of clipping the display values to 4-5 decimal places.

You can rest assured though that anything e-10 is a really small number.

[dpJudas]

The only way I can think of is something like this:

Code: Select all

float AdjustSliderValue(float value, float minValue, float maxValue, int numSteps)
{
    int maxStep = numSteps - 1;
    float sliderLength = (maxValue - minValue);
    int sliderStepValue = std::round((value - minValue) * maxStep / sliderLength);
    float t = sliderStepValue / (float)maxStep;
    return minValue * (1.0f - t) + maxValue * t;
}

[Graf Zahl]

I chose the brute force approach of simply forcing small numbers to zero, it seems the only place where it actually causes problems.

[Blue Shadow]

This can be closed, then.
http://forum.zdoom.org/viewtopic.php?f=2&t=53088