From 250a7d8788057c5009013986fbf8025daa6634e4 Mon Sep 17 00:00:00 2001 From: lawnjelly Date: Tue, 2 Jul 2024 07:42:08 +0100 Subject: [PATCH] Physics Interpolation - Fix `Transform2D::interpolate_with()` Ports the `interpolate_with()` routine from 4.x which works correctly with skew. --- core/math/transform_2d.cpp | 53 ++++++++++------------------ core/math/transform_2d.h | 12 ++++++- core/math/transform_interpolator.cpp | 34 ++---------------- 3 files changed, 31 insertions(+), 68 deletions(-) diff --git a/core/math/transform_2d.cpp b/core/math/transform_2d.cpp index 806c35e8863..ba4691f1009 100644 --- a/core/math/transform_2d.cpp +++ b/core/math/transform_2d.cpp @@ -82,6 +82,24 @@ void Transform2D::set_rotation(real_t p_rot) { set_scale(scale); } +void Transform2D::set_skew(real_t p_angle) { + real_t det = determinant(); + elements[1] = SGN(det) * elements[0].rotated(((real_t)Math_PI * 0.5f + p_angle)).normalized() * elements[1].length(); +} + +real_t Transform2D::get_skew() const { + real_t det = determinant(); + return Math::acos(elements[0].normalized().dot(SGN(det) * elements[1].normalized())) - (real_t)Math_PI * 0.5f; +} + +Transform2D::Transform2D(real_t p_rot, const Size2 &p_scale, real_t p_skew, const Vector2 &p_pos) { + elements[0][0] = Math::cos(p_rot) * p_scale.x; + elements[1][1] = Math::cos(p_rot + p_skew) * p_scale.y; + elements[1][0] = -Math::sin(p_rot + p_skew) * p_scale.y; + elements[0][1] = Math::sin(p_rot) * p_scale.x; + elements[2] = p_pos; +} + Transform2D::Transform2D(real_t p_rot, const Vector2 &p_pos) { real_t cr = Math::cos(p_rot); real_t sr = Math::sin(p_rot); @@ -221,41 +239,6 @@ real_t Transform2D::determinant() const { return elements[0].x * elements[1].y - elements[0].y * elements[1].x; } -Transform2D Transform2D::interpolate_with(const Transform2D &p_transform, real_t p_c) const { - //extract parameters - Vector2 p1 = get_origin(); - Vector2 p2 = p_transform.get_origin(); - - real_t r1 = get_rotation(); - 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, -1, 1); - - Vector2 v; - - if (dot > 0.9995f) { - v = Vector2::linear_interpolate(v1, 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(Math::atan2(v.y, v.x), Vector2::linear_interpolate(p1, p2, p_c)); - res.scale_basis(Vector2::linear_interpolate(s1, s2, p_c)); - return res; -} - Transform2D::operator String() const { return String(String() + elements[0] + ", " + elements[1] + ", " + elements[2]); } diff --git a/core/math/transform_2d.h b/core/math/transform_2d.h index e9b36eafca7..f515cdb48fb 100644 --- a/core/math/transform_2d.h +++ b/core/math/transform_2d.h @@ -71,6 +71,8 @@ struct _NO_DISCARD_CLASS_ Transform2D { void set_rotation(real_t p_rot); real_t get_rotation() const; + void set_skew(real_t p_angle); + real_t get_skew() const; _FORCE_INLINE_ void set_rotation_and_scale(real_t p_rot, const Size2 &p_scale); void rotate(real_t p_angle); @@ -104,7 +106,13 @@ struct _NO_DISCARD_CLASS_ Transform2D { void operator*=(const Transform2D &p_transform); Transform2D operator*(const Transform2D &p_transform) const; - Transform2D interpolate_with(const Transform2D &p_transform, real_t p_c) const; + Transform2D interpolate_with(const Transform2D &p_transform, real_t p_c) const { + return Transform2D( + Math::lerp_angle(get_rotation(), p_transform.get_rotation(), p_c), + get_scale().linear_interpolate(p_transform.get_scale(), p_c), + Math::lerp_angle(get_skew(), p_transform.get_skew(), p_c), + get_origin().linear_interpolate(p_transform.get_origin(), p_c)); + } _FORCE_INLINE_ Vector2 basis_xform(const Vector2 &p_vec) const; _FORCE_INLINE_ Vector2 basis_xform_inv(const Vector2 &p_vec) const; @@ -127,6 +135,8 @@ struct _NO_DISCARD_CLASS_ Transform2D { } Transform2D(real_t p_rot, const Vector2 &p_pos); + Transform2D(real_t p_rot, const Size2 &p_scale, real_t p_skew, const Vector2 &p_pos); + Transform2D() { elements[0][0] = 1.0; elements[1][1] = 1.0; diff --git a/core/math/transform_interpolator.cpp b/core/math/transform_interpolator.cpp index 20e1f560dac..54a5f8cb1c3 100644 --- a/core/math/transform_interpolator.cpp +++ b/core/math/transform_interpolator.cpp @@ -33,46 +33,16 @@ #include "core/math/transform_2d.h" void TransformInterpolator::interpolate_transform_2d(const Transform2D &p_prev, const Transform2D &p_curr, Transform2D &r_result, real_t p_fraction) { - // Extract parameters. - Vector2 p1 = p_prev.get_origin(); - Vector2 p2 = p_curr.get_origin(); - // Special case for physics interpolation, if flipping, don't interpolate basis. // If the determinant polarity changes, the handedness of the coordinate system changes. if (_sign(p_prev.determinant()) != _sign(p_curr.determinant())) { r_result.elements[0] = p_curr.elements[0]; r_result.elements[1] = p_curr.elements[1]; - r_result.set_origin(Vector2::linear_interpolate(p1, p2, p_fraction)); + r_result.set_origin(Vector2::linear_interpolate(p_prev.get_origin(), p_curr.get_origin(), p_fraction)); return; } - real_t r1 = p_prev.get_rotation(); - real_t r2 = p_curr.get_rotation(); - - Size2 s1 = p_prev.get_scale(); - Size2 s2 = p_curr.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, -1, 1); - - Vector2 v; - - if (dot > 0.9995f) { - v = Vector2::linear_interpolate(v1, v2, p_fraction).normalized(); // Linearly interpolate to avoid numerical precision issues. - } else { - real_t angle = p_fraction * Math::acos(dot); - Vector2 v3 = (v2 - v1 * dot).normalized(); - v = v1 * Math::cos(angle) + v3 * Math::sin(angle); - } - - // Construct matrix. - r_result = Transform2D(Math::atan2(v.y, v.x), Vector2::linear_interpolate(p1, p2, p_fraction)); - r_result.scale_basis(Vector2::linear_interpolate(s1, s2, p_fraction)); + r_result = p_prev.interpolate_with(p_curr, p_fraction); } void TransformInterpolator::interpolate_transform(const Transform &p_prev, const Transform &p_curr, Transform &r_result, real_t p_fraction) {