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Implement Skew in Node2D

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Skew is x-axis only, because it must be bidirectionally convertible to a 2x3 matrix, but you can subtract it  to the rotation to get the effect on y-axis
This commit is contained in:
Juan Linietsky 2020-05-01 13:38:04 -03:00
parent 316b60aa68
commit efb1f7d76b
4 changed files with 68 additions and 2 deletions
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12
core/math/transform_2d.cpp
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@ -70,6 +70,18 @@ void Transform2D::rotate(real_t p_phi) {
*this = Transform2D(p_phi, Vector2()) * (*this);
}
real_t Transform2D::get_skew() const {
real_t det = basis_determinant();
return Math::acos(elements[0].normalized().dot(SGN(det) * elements[1].normalized())) - Math_PI * 0.5;
}
void Transform2D::set_skew(float p_angle) {
real_t det = basis_determinant();
elements[1] = SGN(det) * elements[0].rotated((Math_PI * 0.5 + p_angle)).normalized() * elements[1].length();
}
real_t Transform2D::get_rotation() const {
real_t det = basis_determinant();
Transform2D m = orthonormalized();

11
core/math/transform_2d.h
View file

@ -70,7 +70,10 @@ struct Transform2D {
void set_rotation(real_t p_rot);
real_t get_rotation() const;
real_t get_skew() const;
void set_skew(float p_angle);
_FORCE_INLINE_ void set_rotation_and_scale(real_t p_rot, const Size2 &p_scale);
_FORCE_INLINE_ void set_rotation_scale_and_skew(real_t p_rot, const Size2 &p_scale, float p_skew);
void rotate(real_t p_phi);
void scale(const Size2 &p_scale);
@ -184,6 +187,14 @@ void Transform2D::set_rotation_and_scale(real_t p_rot, const Size2 &p_scale) {
elements[0][1] = Math::sin(p_rot) * p_scale.x;
}
void Transform2D::set_rotation_scale_and_skew(real_t p_rot, const Size2 &p_scale, float p_skew) {
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;
}
Rect2 Transform2D::xform_inv(const Rect2 &p_rect) const {
Vector2 ends[4] = {