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Use safe circle to square calculation for gamepad (#1618)

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Check sign early to prevent input from being set to zero for e.g. small values of y but large values of x. Additionally, guard against negative square roots and clamp x/y values.
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ceski 2024-03-26 23:17:16 -07:00 committed by GitHub
parent 481b8de46d
commit bb47d3f103
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1 changed files with 26 additions and 10 deletions
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src/i_gamepad.c
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@ -132,23 +132,39 @@ static void CalcExtraScale(axes_t *ax, float magnitude)
// https://squircular.blogspot.com/2015/09/fg-squircle-mapping.html // https://squircular.blogspot.com/2015/09/fg-squircle-mapping.html
// //
#define MIN_C2S 0.000001f
static void CircleToSquare(float *x, float *y) static void CircleToSquare(float *x, float *y)
{ {
const float u = *x; const float u = *x;
const float v = *y; const float v = *y;
const float r2 = u * u + v * v;
if (fabsf(u) > MIN_C2S && fabsf(v) > MIN_C2S)
{
const float uv = u * v; const float uv = u * v;
const float sgnuv = SGNF(uv); const float sgnuv = SGNF(uv);
const float sqrto = sqrtf(0.5f * (r2 - sqrtf(r2 * (r2 - 4.0f * uv * uv))));
if (fabsf(u) > 0.000001f) if (sgnuv)
{ {
*y = sgnuv / u * sqrto; const float r2 = u * u + v * v;
} const float rad = r2 * (r2 - 4.0f * uv * uv);
if (fabsf(v) > 0.000001f) if (rad > 0.0f)
{ {
const float r2rad = 0.5f * (r2 - sqrtf(rad));
if (r2rad > 0.0f)
{
const float sqrto = sqrtf(r2rad);
*x = sgnuv / v * sqrto; *x = sgnuv / v * sqrto;
*y = sgnuv / u * sqrto;
*x = BETWEEN(-1.0f, 1.0f, *x);
*y = BETWEEN(-1.0f, 1.0f, *y);
}
}
}
} }
} }