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Fix precision in physics supports generation
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Lower threshold for dot was (1.0 - threshold) which is incorrect.
Patch changes it to correct version sqrt(1.0 - threshold * threshold)

Co-authored-by: Ricardo Buring <[email protected]>
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@Black-Cat @rburing
Black-Cat and rburing committed Apr 29, 2023
1 parent 9f12e7b commit d710af2
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Showing 3 changed files with 25 additions and 23 deletions.
11 changes: 5 additions & 6 deletions servers/physics_2d/godot_shape_2d.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -179,7 +179,7 @@ Variant GodotSeparationRayShape2D::get_data() const {
/*********************************************************/

void GodotSegmentShape2D::get_supports(const Vector2 &p_normal, Vector2 *r_supports, int &r_amount) const {
if (Math::abs(p_normal.dot(n)) > _SEGMENT_IS_VALID_SUPPORT_THRESHOLD) {
if (Math::abs(p_normal.dot(n)) > segment_is_valid_support_threshold) {
r_supports[0] = a;
r_supports[1] = b;
r_amount = 2;
Expand Down Expand Up @@ -308,7 +308,7 @@ void GodotRectangleShape2D::get_supports(const Vector2 &p_normal, Vector2 *r_sup
Vector2 ag;
ag[i] = 1.0;
real_t dp = ag.dot(p_normal);
if (Math::abs(dp) < _SEGMENT_IS_VALID_SUPPORT_THRESHOLD) {
if (Math::abs(dp) <= segment_is_valid_support_threshold) {
continue;
}

Expand Down Expand Up @@ -368,10 +368,9 @@ Variant GodotRectangleShape2D::get_data() const {
void GodotCapsuleShape2D::get_supports(const Vector2 &p_normal, Vector2 *r_supports, int &r_amount) const {
Vector2 n = p_normal;

real_t d = n.y;
real_t h = height * 0.5 - radius; // half-height of the rectangle part

if (h > 0 && Math::abs(d) < (1.0 - _SEGMENT_IS_VALID_SUPPORT_THRESHOLD)) {
if (h > 0 && Math::abs(n.x) > segment_is_valid_support_threshold) {
// make it flat
n.y = 0.0;
n.normalize();
Expand All @@ -384,7 +383,7 @@ void GodotCapsuleShape2D::get_supports(const Vector2 &p_normal, Vector2 *r_suppo
r_supports[1].y -= h;
} else {
n *= radius;
n.y += (d > 0) ? h : -h;
n.y += (n.y > 0) ? h : -h;
r_amount = 1;
*r_supports = n;
}
Expand Down Expand Up @@ -506,7 +505,7 @@ void GodotConvexPolygonShape2D::get_supports(const Vector2 &p_normal, Vector2 *r
}

//test segment
if (points[i].normal.dot(p_normal) > _SEGMENT_IS_VALID_SUPPORT_THRESHOLD) {
if (points[i].normal.dot(p_normal) > segment_is_valid_support_threshold) {
r_amount = 2;
r_supports[0] = points[i].pos;
r_supports[1] = points[(i + 1) % point_count].pos;
Expand Down
9 changes: 6 additions & 3 deletions servers/physics_2d/godot_shape_2d.h
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Original file line number Diff line number Diff line change
Expand Up @@ -32,7 +32,6 @@
#define GODOT_SHAPE_2D_H

#include "servers/physics_server_2d.h"
#define _SEGMENT_IS_VALID_SUPPORT_THRESHOLD 0.99998

class GodotShape2D;

Expand All @@ -53,6 +52,10 @@ class GodotShape2D {
HashMap<GodotShapeOwner2D *, int> owners;

protected:
const double segment_is_valid_support_threshold = 0.99998;
const double segment_is_valid_support_threshold_lower =
Math::sqrt(1.0 - segment_is_valid_support_threshold * segment_is_valid_support_threshold);

void configure(const Rect2 &p_aabb);

public:
Expand Down Expand Up @@ -95,7 +98,7 @@ class GodotShape2D {
}

if (r_amount == 1) {
if (Math::abs(p_normal.dot(p_cast.normalized())) < (1.0 - _SEGMENT_IS_VALID_SUPPORT_THRESHOLD)) {
if (Math::abs(p_normal.dot(p_cast.normalized())) < segment_is_valid_support_threshold_lower) {
//make line because they are parallel
r_amount = 2;
r_supports[1] = r_supports[0] + p_cast;
Expand All @@ -105,7 +108,7 @@ class GodotShape2D {
}

} else {
if (Math::abs(p_normal.dot(p_cast.normalized())) < (1.0 - _SEGMENT_IS_VALID_SUPPORT_THRESHOLD)) {
if (Math::abs(p_normal.dot(p_cast.normalized())) < segment_is_valid_support_threshold_lower) {
//optimize line and make it larger because they are parallel
if ((r_supports[1] - r_supports[0]).dot(p_cast) > 0) {
//larger towards 1
Expand Down
28 changes: 14 additions & 14 deletions servers/physics_3d/godot_shape_3d.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -52,11 +52,11 @@ subject to the following restrictions:
3. This notice may not be removed or altered from any source distribution.
*/

constexpr double edge_support_threshold = 0.0002;
constexpr double face_support_threshold = 0.9998;
const double support_threshold = 0.9998;
const double support_threshold_lower = Math::sqrt(1.0 - support_threshold * support_threshold);

constexpr double cylinder_edge_support_threshold = 0.002;
constexpr double cylinder_face_support_threshold = 0.999;
const double cylinder_support_threshold = 0.999;
const double cylinder_support_threshold_lower = Math::sqrt(1.0 - cylinder_support_threshold * cylinder_support_threshold);

void GodotShape3D::configure(const AABB &p_aabb) {
aabb = p_aabb;
Expand Down Expand Up @@ -184,7 +184,7 @@ Vector3 GodotSeparationRayShape3D::get_support(const Vector3 &p_normal) const {
}

void GodotSeparationRayShape3D::get_supports(const Vector3 &p_normal, int p_max, Vector3 *r_supports, int &r_amount, FeatureType &r_type) const {
if (Math::abs(p_normal.z) < edge_support_threshold) {
if (Math::abs(p_normal.z) < support_threshold_lower) {
r_amount = 2;
r_type = FEATURE_EDGE;
r_supports[0] = Vector3(0, 0, 0);
Expand Down Expand Up @@ -335,7 +335,7 @@ void GodotBoxShape3D::get_supports(const Vector3 &p_normal, int p_max, Vector3 *
Vector3 axis;
axis[i] = 1.0;
real_t dot = p_normal.dot(axis);
if (Math::abs(dot) > face_support_threshold) {
if (Math::abs(dot) > support_threshold) {
//Vector3 axis_b;

bool neg = dot < 0;
Expand Down Expand Up @@ -376,7 +376,7 @@ void GodotBoxShape3D::get_supports(const Vector3 &p_normal, int p_max, Vector3 *
Vector3 axis;
axis[i] = 1.0;

if (Math::abs(p_normal.dot(axis)) < edge_support_threshold) {
if (Math::abs(p_normal.dot(axis)) < support_threshold_lower) {
r_amount = 2;
r_type = FEATURE_EDGE;

Expand Down Expand Up @@ -523,7 +523,7 @@ void GodotCapsuleShape3D::get_supports(const Vector3 &p_normal, int p_max, Vecto
real_t d = n.y;
real_t h = height * 0.5 - radius; // half-height of the cylinder part

if (h > 0 && Math::abs(d) < edge_support_threshold) {
if (h > 0 && Math::abs(d) < support_threshold_lower) {
// make it flat
n.y = 0.0;
n.normalize();
Expand Down Expand Up @@ -701,7 +701,7 @@ Vector3 GodotCylinderShape3D::get_support(const Vector3 &p_normal) const {

void GodotCylinderShape3D::get_supports(const Vector3 &p_normal, int p_max, Vector3 *r_supports, int &r_amount, FeatureType &r_type) const {
real_t d = p_normal.y;
if (Math::abs(d) > cylinder_face_support_threshold) {
if (Math::abs(d) > cylinder_support_threshold) {
real_t h = (d > 0) ? height : -height;

Vector3 n = p_normal;
Expand All @@ -716,7 +716,7 @@ void GodotCylinderShape3D::get_supports(const Vector3 &p_normal, int p_max, Vect
r_supports[1].x += radius;
r_supports[2] = n;
r_supports[2].z += radius;
} else if (Math::abs(d) < cylinder_edge_support_threshold) {
} else if (Math::abs(d) < cylinder_support_threshold_lower) {
// make it flat
Vector3 n = p_normal;
n.y = 0.0;
Expand Down Expand Up @@ -925,7 +925,7 @@ void GodotConvexPolygonShape3D::get_supports(const Vector3 &p_normal, int p_max,
}

for (int i = 0; i < fc; i++) {
if (faces[i].plane.normal.dot(p_normal) > face_support_threshold) {
if (faces[i].plane.normal.dot(p_normal) > support_threshold) {
int ic = faces[i].indices.size();
const int *ind = faces[i].indices.ptr();

Expand Down Expand Up @@ -954,7 +954,7 @@ void GodotConvexPolygonShape3D::get_supports(const Vector3 &p_normal, int p_max,
for (int i = 0; i < ec; i++) {
real_t dot = (vertices[edges[i].vertex_a] - vertices[edges[i].vertex_b]).normalized().dot(p_normal);
dot = ABS(dot);
if (dot < edge_support_threshold && (edges[i].vertex_a == vtx || edges[i].vertex_b == vtx)) {
if (dot < support_threshold_lower && (edges[i].vertex_a == vtx || edges[i].vertex_b == vtx)) {
r_amount = 2;
r_type = FEATURE_EDGE;
r_supports[0] = vertices[edges[i].vertex_a];
Expand Down Expand Up @@ -1197,7 +1197,7 @@ void GodotFaceShape3D::get_supports(const Vector3 &p_normal, int p_max, Vector3
Vector3 n = p_normal;

/** TEST FACE AS SUPPORT **/
if (Math::abs(normal.dot(n)) > face_support_threshold) {
if (Math::abs(normal.dot(n)) > support_threshold) {
r_amount = 3;
r_type = FEATURE_FACE;
for (int i = 0; i < 3; i++) {
Expand Down Expand Up @@ -1231,7 +1231,7 @@ void GodotFaceShape3D::get_supports(const Vector3 &p_normal, int p_max, Vector3
// check if edge is valid as a support
real_t dot = (vertex[i] - vertex[nx]).normalized().dot(n);
dot = ABS(dot);
if (dot < edge_support_threshold) {
if (dot < support_threshold_lower) {
r_amount = 2;
r_type = FEATURE_EDGE;
r_supports[0] = vertex[i];
Expand Down

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