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Add support for interpolating skewed transforms

This commit is contained in:
Aaron Franke 2023-01-28 17:27:32 -06:00
parent 218bef90af
commit 5f3d3722b2
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GPG Key ID: 40A1750B977E56BF
2 changed files with 19 additions and 33 deletions
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39
core/math/transform_2d.cpp
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@ -263,39 +263,12 @@ real_t Transform2D::basis_determinant() const {
return columns[0].x * columns[1].y - columns[0].y * columns[1].x; return columns[0].x * columns[1].y - columns[0].y * columns[1].x;
} }
Transform2D Transform2D::interpolate_with(const Transform2D &p_transform, const real_t p_c) const { Transform2D Transform2D::interpolate_with(const Transform2D &p_transform, const real_t p_weight) const {
//extract parameters return Transform2D(
Vector2 p1 = get_origin(); Math::lerp_angle(get_rotation(), p_transform.get_rotation(), p_weight),
Vector2 p2 = p_transform.get_origin(); get_scale().lerp(p_transform.get_scale(), p_weight),
Math::lerp_angle(get_skew(), p_transform.get_skew(), p_weight),
real_t r1 = get_rotation(); get_origin().lerp(p_transform.get_origin(), p_weight));
real_t r2 = p_transform.get_rotation();
Size2 s1 = get_scale();
Size2 s2 = p_transform.get_scale();
//slerp rotation
Vector2 v1(Math::cos(r1), Math::sin(r1));
Vector2 v2(Math::cos(r2), Math::sin(r2));
real_t dot = v1.dot(v2);
dot = CLAMP(dot, (real_t)-1.0, (real_t)1.0);
Vector2 v;
if (dot > 0.9995f) {
v = v1.lerp(v2, p_c).normalized(); //linearly interpolate to avoid numerical precision issues
} else {
real_t angle = p_c * Math::acos(dot);
Vector2 v3 = (v2 - v1 * dot).normalized();
v = v1 * Math::cos(angle) + v3 * Math::sin(angle);
}
//construct matrix
Transform2D res(v.angle(), p1.lerp(p2, p_c));
res.scale_basis(s1.lerp(s2, p_c));
return res;
} }
void Transform2D::operator*=(const real_t p_val) { void Transform2D::operator*=(const real_t p_val) {

13
tests/core/math/test_transform_2d.h
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@ -84,6 +84,19 @@ TEST_CASE("[Transform2D] rotation") {
CHECK(orig.rotated_local(phi) == orig * R); CHECK(orig.rotated_local(phi) == orig * R);
} }
TEST_CASE("[Transform2D] Interpolation") {
Transform2D rotate_scale_skew_pos = Transform2D(Math::deg_to_rad(170.0), Vector2(3.6, 8.0), Math::deg_to_rad(20.0), Vector2(2.4, 6.8));
Transform2D rotate_scale_skew_pos_halfway = Transform2D(Math::deg_to_rad(85.0), Vector2(2.3, 4.5), Math::deg_to_rad(10.0), Vector2(1.2, 3.4));
Transform2D interpolated = Transform2D().interpolate_with(rotate_scale_skew_pos, 0.5);
CHECK(interpolated.get_origin().is_equal_approx(rotate_scale_skew_pos_halfway.get_origin()));
CHECK(interpolated.get_rotation() == doctest::Approx(rotate_scale_skew_pos_halfway.get_rotation()));
CHECK(interpolated.get_scale().is_equal_approx(rotate_scale_skew_pos_halfway.get_scale()));
CHECK(interpolated.get_skew() == doctest::Approx(rotate_scale_skew_pos_halfway.get_skew()));
CHECK(interpolated.is_equal_approx(rotate_scale_skew_pos_halfway));
interpolated = rotate_scale_skew_pos.interpolate_with(Transform2D(), 0.5);
CHECK(interpolated.is_equal_approx(rotate_scale_skew_pos_halfway));
}
TEST_CASE("[Transform2D] Finite number checks") { TEST_CASE("[Transform2D] Finite number checks") {
const Vector2 x(0, 1); const Vector2 x(0, 1);
const Vector2 infinite(NAN, NAN); const Vector2 infinite(NAN, NAN);