avm2: Make PerspectiveProjection.focalLength more precise #19748
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The previous calculation for focalLength was correct in semantics, but the difference from FP was not tiny. The calculation involves trigonometric functions in floating point number and this semantically-equivalent refactoring makes the result of focalLength calculation closer to that of FP.
Move approximation logic from ActionScript to Ruffle test framework
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Mar 8, 2025
| @@ -40,7 +40,7 @@ pub fn get_focal_length<'gc>( | |||
| let fov = this.get_slot(pp_slots::FOV).coerce_to_number(activation)?; | |||
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| let width = get_width(activation, this); | |||
| let focal_length = (width / 2.0) / f64::tan(fov / 2.0 * DEG2RAD); | |||
| let focal_length = (width / 2.0) as f32 * f64::tan((PI - fov * DEG2RAD) / 2.0) as f32; | |||
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After many trials and observations, I found this code. It doesn't seem to be perfect yet (for edge values like 1e-10), though.
1 / tan x=cot x=tan (pi/2 - x)_ as f32 * f32::tan(_)is not good. This produces better result.
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| 'fieldOfView = ([0-9.]+)', | ||
| 'FOV [0-9]+ ([0-9.]+)', |
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field of view still has some errors.
var pp: PerspectiveProjection = new PerspectiveProjection();
pp.fieldOfView = 179.99999;
trace(pp.fieldOfView);
I found the code above gives 179.99999000000003, so even pp.fieldOfView is not a simple storage variable.
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Small follow up to #19532
The previous
focalLengthgetter had a certain level of difference. This change reduces the difference from Flash Player.Also, I found Ruffle
test.tomlhas the configuration section for number approximations, so move the logic fromTest.as.