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func_8017FB1C documentation

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Co-authored-by: EllipticEllipsis <73679967+EllipticEllipsis@users.noreply.github.com>
This commit is contained in:
angie
2022-04-11 09:35:24 -04:00
co-authored by EllipticEllipsis
parent 9cd74ce160
commit ef5e39fbd2
1 changed files with 60 additions and 39 deletions
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src/code/sys_math3d.c
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@@ -2273,55 +2273,76 @@ s32 Math3D_YZInSphere(Sphere16* sphere, f32 y, f32 z) {
return false;
}
s32 func_8017FB1C(f32 arg0, f32 arg1, f32 arg2, f32 arg3, f32 arg4, f32 arg5, f32 arg6, f32* arg7, f32* arg8, f32* arg9,
f32* argA) {
f32 temp_fa0;
f32 temp_fa1;
f32 temp_fs0;
f32 temp_fv0;
f32 temp_ft5;
f32 temp_fv1;
f32 temp_ft2;
s32 phi_a1;
temp_fa1 = SQ(arg5) + SQ(arg6);
temp_fv1 = arg3 - arg0;
temp_fa0 = arg4 - arg1;
// Math3D_CircleLineIntersections?
/**
* @brief Computes the intersection points, if any, of the circle of radius radius, center (centerX, centerY) with the
* line through the point (pointX, pointY) in direction (dirX, dirY).
*
* @param[in] centreX x coordinate of centre of circle
* @param[in] centerY y coordinate of centre of circle
* @param[in] radius of circle
* @param[in] pointX x coordinate of point on line
* @param[in] pointY y coordinate of point on line
* @param[in] dirX x value of direction vector of line
* @param[in] dirY y value of direction vecotr of line
* @param[out] intersectAX x coordinate of first intersection
* @param[out] intersectAY y coordinate of first intersection
* @param[out] intersectBX x coordinate of second intersection
* @param[out] intersectBY y coordinate of second intersection
* @return number of intersections(ish)
*/
s32 func_8017FB1C(f32 centreX, f32 centerY, f32 radius, f32 pointX, f32 pointY, f32 dirX, f32 dirY, f32* intersectAX,
f32* intersectAY, f32* intersectBX, f32* intersectBY) {
f32 a = SQ(dirX) + SQ(dirY); // t^2 coefficient, |dir|^2
f32 diffX = pointX - centreX;
f32 diffY = pointY - centerY;
f32 b; // t coefficient
f32 delta; // discriminant of quadratic
f32 rootP; // larger root of quadratic
f32 rootN; // smaller root of quadratic
s32 ret;
if ((IS_ZERO(arg5) && IS_ZERO(arg6)) || IS_ZERO(temp_fa1)) {
*arg7 = 0.0f;
*arg8 = 0.0f;
*arg9 = 0.0f;
*argA = 0.0f;
// if the direction vector's magnitude is too small, assume no intersections
if ((IS_ZERO(dirX) && IS_ZERO(dirY)) || IS_ZERO(a)) {
*intersectAX = 0.0f;
*intersectAY = 0.0f;
*intersectBX = 0.0f;
*intersectBY = 0.0f;
return 0;
}
temp_fs0 = 2.0f * ((arg5 * temp_fv1) + (arg6 * temp_fa0));
temp_ft5 = SQ(temp_fs0) - (4.0f * temp_fa1 * ((SQ(temp_fv1) + SQ(temp_fa0)) - SQ(arg2)));
phi_a1 = 0;
b = 2.0f * (dirX * diffX + dirY * diffY); // 2 dir . (point - centre)
delta = SQ(b) - 4.0f * a * (SQ(diffX) + SQ(diffY) - SQ(radius));
ret = 0;
if (IS_ZERO(temp_ft5)) {
temp_fv0 = (-temp_fs0 / (2.0f * temp_fa1));
*arg7 = (arg5 * temp_fv0) + arg3;
*arg8 = (arg6 * temp_fv0) + arg4;
*arg9 = 0.0f;
*argA = 0.0f;
if (IS_ZERO(delta)) { // At most one root if discriminant is close to zero
// This root is always overwritten later.
rootN = -b / (2.0f * a);
*intersectAX = dirX * rootN + pointX;
*intersectAY = dirY * rootN + pointY;
*intersectBX = 0.0f;
*intersectBY = 0.0f;
}
if (temp_ft5 > 0.0f) {
temp_fv0 = ((-temp_fs0 - sqrtf(temp_ft5)) / (2.0f * temp_fa1));
temp_ft2 = ((-temp_fs0 + sqrtf(temp_ft5)) / (2.0f * temp_fa1));
*arg7 = (arg5 * temp_fv0) + arg3;
*arg8 = (arg6 * temp_fv0) + arg4;
*arg9 = (arg5 * temp_ft2) + arg3;
*argA = (arg6 * temp_ft2) + arg4;
phi_a1 = 2;
} else {
*arg7 = 0.0f;
*arg8 = 0.0f;
if (delta > 0.0f) { // Two roots if discriminant > 0
rootN = (-b - sqrtf(delta)) / (2.0f * a);
*intersectAX = dirX * rootN + pointX;
*intersectAY = dirY * rootN + pointY;
rootP = (-b + sqrtf(delta)) / (2.0f * a);
*intersectBX = dirX * rootP + pointX;
*intersectBY = dirY * rootP + pointY;
ret = 2;
} else { // "No roots if discriminant <= 0.0f"*
//! @bug Should be one root if discriminant == 0, not zero (although this case is unlikely for floats)
*intersectAX = 0.0f;
*intersectAY = 0.0f;
}
return phi_a1;
return ret;
}
void func_8017FD44(Vec3f* arg0, Vec3f* arg1, Vec3f* dst, f32 arg3) {