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collision: add closest point segment segment

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This commit is contained in:
Zack Buhman 2026-03-13 21:46:17 -05:00
parent ee3179899d
commit e38d9338d9
6 changed files with 182 additions and 22 deletions
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88
include/collision.h
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@ -79,4 +79,92 @@ namespace collision {
return true;
}
static inline float clamp(float f, float min, float max)
{
if (f < min) return min;
if (f > max) return max;
return f;
}
static inline void closest_point_segment_segment(XMVECTOR const & a1, XMVECTOR const & b1, // segment 1
XMVECTOR const & a2, XMVECTOR const & b2, // segment 2
float & t1, // (s)
float & t2, // (t)
XMVECTOR & c1, // closest point to segment 1
XMVECTOR & c2) // closest point to segment 2
{
const float epsilon = 1.192092896e-7f;
XMVECTOR d1 = b1 - a1;
XMVECTOR d2 = b2 - a2;
XMVECTOR r = a1 - a2;
float l1 = XMVectorGetX(XMVector3Dot(d1, d1)); // squared length of segment 1 (a)
float l2 = XMVectorGetX(XMVector3Dot(d2, d2)); // squared length of segment 2 (e)
float d1r = XMVectorGetX(XMVector3Dot(d1, r)); // (c)
float d2r = XMVectorGetX(XMVector3Dot(d2, r)); // (f)
if (l1 <= epsilon && l2 <= epsilon) {
// both segments are points
t1 = 0.0f;
t2 = 0.0f;
c1 = a1;
c2 = a2;
return;
}
if (l1 <= epsilon) {
// segment 1 is a point
t1 = 0.0f;
t2 = clamp(d2r / l2, 0.0f, 1.0f);
} else if (l2 <= epsilon) {
// segment 2 is a point
t1 = clamp(-d1r / l1, 0.0, 1.0f);
t2 = 0.0f;
} else {
float b = XMVectorGetX(XMVector3Dot(d1, d2));
float denom = l1 * l2 - b * b;
if (denom != 0.0f) {
// segments are not parallel
t1 = clamp((b * d2r - d1r * l2) / denom, 0.0f, 1.0f);
} else {
t1 = 0.0f;
}
t2 = (b * t1 + d2r) / l2;
if (t2 < 0.0f) {
t2 = 0.0f;
t1 = clamp(-d1r / l1, 0.0f, 1.0f);
} else if (t2 > 1.0f) {
t2 = 1.0f;
t1 = clamp((b - d1r) / l1, 0.0f, 1.0f);
}
}
c1 = a1 + d1 * t1;
c2 = a2 + d2 * t2;
}
static inline bool intersect_moving_sphere_aabb(Sphere const & sphere, XMVECTOR const & direction, AABB const & aabb, float & t)
{
AABB expand(expand.min - XMVectorReplicate(sphere.radius),
expand.max + XMVectorReplicate(sphere.radius));
// intersect ray against expand
XMVECTOR point;
bool intersection = intersect_ray_aabb(sphere.center, direction, expand, t, point);
if (!intersection || t > 1.0f)
return false;
XMVECTOR lt = XMVectorLess(point, aabb.min);
int u = 0;
if (XMVectorGetX(lt) != 0) u |= 1;
if (XMVectorGetY(lt) != 0) u |= 2;
if (XMVectorGetZ(lt) != 0) u |= 4;
XMVECTOR gt = XMVectorGreater(point, aabb.max);
int v = 0;
if (XMVectorGetX(gt) != 0) v |= 1;
if (XMVectorGetY(gt) != 0) v |= 2;
if (XMVectorGetZ(gt) != 0) v |= 4;
int mask = u + v;
}
}

4
include/collision_scene.h
View File

@ -4,5 +4,7 @@ namespace collision_scene {
void load();
void draw();
void update(int up, int down, int left, int right,
int w, int s, int a, int d);
int w, int s, int a, int d,
int t, int g, int f, int h,
int i, int k, int j, int l);
}

4
include/test.h
View File

@ -7,7 +7,9 @@ extern "C" {
void load(const char * source_path);
void draw();
void update_keyboard(int up, int down, int left, int right,
int w, int s, int a, int d);
int w, int s, int a, int d,
int t, int g, int f, int h,
int i, int k, int j, int l);
void update_mouse(int x, int y);
void update_joystick(int joystick_index,
float lx, float ly, float rx, float ry, float tl, float tr,

17
main.lua
View File

@ -12,7 +12,9 @@ void load(const char * source_path);
void update_window(int width, int height);
void draw();
void update_keyboard(int up, int down, int left, int right,
int w, int s, int a, int d);
int w, int s, int a, int d,
int t, int g, int f, int h,
int i, int k, int j, int l);
void update_mouse(int x, int y);
void update_joystick(int joystick_index,
float lx, float ly, float rx, float ry, float tl, float tr,
@ -66,7 +68,18 @@ local update = function(time)
local s = love.keyboard.isDown("s")
local a = love.keyboard.isDown("a")
local d = love.keyboard.isDown("d")
test.update_keyboard(up, down, left, right, w, s, a, d);
local t = love.keyboard.isDown("t")
local g = love.keyboard.isDown("g")
local f = love.keyboard.isDown("f")
local h = love.keyboard.isDown("h")
local i = love.keyboard.isDown("i")
local k = love.keyboard.isDown("k")
local j = love.keyboard.isDown("j")
local l = love.keyboard.isDown("l")
test.update_keyboard(up, down, left, right,
w, s, a, d,
t, g, f, h,
i, k, j, l);
test.update(time)
end

83
src/collision_scene.cpp
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@ -26,8 +26,7 @@ namespace collision_scene {
static unsigned int index_buffer;
static XMVECTOR point_position;
static XMVECTOR point_1_position;
static XMVECTOR point_position[4];
static unsigned int ray_vertex_buffer;
@ -150,8 +149,8 @@ namespace collision_scene {
load_index_buffer();
point_position = XMVectorSet(0, 0, 0, 1);
point_1_position = XMVectorSet(0, 0, 0, 1);
for (int i = 0; i < 4; i++)
point_position[i] = XMVectorSet(0, 0, 0, 1);
// ray buffer
glGenBuffers(1, &ray_vertex_buffer);
@ -183,19 +182,32 @@ namespace collision_scene {
return XMMatrixOrthographicRH(10, 10, 0, 10);
}
const float point_radius = 0.05f;
void update(int up, int down, int left, int right,
int w, int s, int a, int d)
int w, int s, int a, int d,
int t, int g, int f, int h,
int i, int k, int j, int l)
{
float rate = 0.05f;
float forward = (rate * up + -rate * down);
float strafe = (-rate * left + rate * right);
float forward_1 = (rate * w + -rate * s);
float strafe_1 = (-rate * a + rate * d);
float forward[4];
float strafe[4];
point_position = XMVector3Transform(point_position, XMMatrixTranslation(strafe, forward, 0));
forward[0] = (rate * up + -rate * down);
strafe[0] = (-rate * left + rate * right);
point_1_position = XMVector3Transform(point_1_position, XMMatrixTranslation(strafe_1, forward_1, 0));
forward[1] = (rate * w + -rate * s);
strafe[1] = (-rate * a + rate * d);
forward[2] = (rate * t + -rate * g);
strafe[2] = (-rate * f + rate * h);
forward[3] = (rate * i + -rate * k);
strafe[3] = (-rate * j + rate * l);
for (int i = 0; i < 4; i++)
point_position[i] = XMVector3Transform(point_position[i], XMMatrixTranslation(strafe[i], forward[i], 0));
}
static inline void set_transform(XMMATRIX const & transform)
@ -227,9 +239,17 @@ namespace collision_scene {
glDrawElementsBaseVertex(GL_LINE_STRIP, 33, GL_UNSIGNED_SHORT, (void*)(circle_base_index), circle_base_vertex);
}
void draw_capsule(XMVECTOR a, XMVECTOR b, float radius)
void draw_capsule(XMMATRIX const & transform, XMVECTOR a, XMVECTOR b, float radius)
{
draw_sphere(transform, a, radius);
draw_sphere(transform, b, radius);
XMVECTOR abn = XMVector3Normalize(a - b);
XMVECTOR p = XMVectorSet(0, 0, 1, 0);
XMVECTOR pxabn = XMVector3Cross(abn, p);
draw_line(transform, a + pxabn * radius, b + pxabn * radius);
draw_line(transform, a - pxabn * radius, b - pxabn * radius);
}
void draw()
@ -245,16 +265,42 @@ namespace collision_scene {
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, index_buffer);
XMMATRIX transform = view() * projection();
XMFLOAT4X4 float_transform;
XMStoreFloat4x4(&float_transform, transform);
// grid
glUniformMatrix4fv(location.uniform.transform, 1, false, (float *)&float_transform);
set_transform(transform);
glUniform3f(location.uniform.base_color, 0, 1, 0);
glUniform1i(location.uniform.use_grid_transform, 1);
glDrawArraysInstanced(GL_LINES, 0, 4, 7);
glUniform1i(location.uniform.use_grid_transform, 0);
// segments
glUniform3f(location.uniform.base_color, 0, 0.5, 1.0);
draw_line(transform, point_position[0], point_position[1]);
glUniform3f(location.uniform.base_color, 0, 1.0, 0.5);
draw_line(transform, point_position[2], point_position[3]);
// points
glUniform3f(location.uniform.base_color, 0, 0.5, 1.0);
draw_sphere(transform, point_position[0], point_radius);
draw_sphere(transform, point_position[1], point_radius);
glUniform3f(location.uniform.base_color, 0, 1.0, 0.5);
draw_sphere(transform, point_position[2], point_radius);
draw_sphere(transform, point_position[3], point_radius);
float t1, t2;
XMVECTOR c1, c2;
collision::closest_point_segment_segment(point_position[0], point_position[1],
point_position[2], point_position[3],
t1, t2, c1, c2);
glUniform3f(location.uniform.base_color, 1.0, 0.0, 0.0);
draw_sphere(transform, c1, point_radius);
glUniform3f(location.uniform.base_color, 1.0, 0.5, 0.0);
draw_sphere(transform, c2, point_radius);
// cube
/*
float cube_half = 0.5;
XMVECTOR cube_position = XMVectorSet(1, 0, 0, 0);
XMMATRIX cube_transform
@ -269,7 +315,6 @@ namespace collision_scene {
glDrawElementsBaseVertex(GL_LINE_STRIP, 5, GL_UNSIGNED_SHORT, (void*)(cube_base_index), cube_base_vertex);
// circle
const float point_radius = 0.05f;
glUniform3f(location.uniform.base_color, 1.0, 0.5, 0.0);
draw_sphere(transform, point_position, point_radius);
@ -288,5 +333,11 @@ namespace collision_scene {
glUniform3f(location.uniform.base_color, 0.5, 0.5, 0.5);
draw_line(transform, point_position, point_position + direction * 20.0f);
}
glUniform3f(location.uniform.base_color, 0.5, 0.0, 0.5);
XMVECTOR ca = XMVectorSet(1, 2.5, 0, 0);
XMVECTOR cb = XMVectorSet(-1, 2, 0, 0);
draw_capsule(transform, ca, cb, 0.5);
*/
}
}

8
src/test.cpp
View File

@ -288,13 +288,17 @@ void load(const char * source_path)
}
void update_keyboard(int up, int down, int left, int right,
int w, int s, int a, int d)
int w, int s, int a, int d,
int t, int g, int f, int h,
int i, int k, int j, int l)
{
//float forward = (0.1f * up + -0.1f * down);
//float strafe = (-0.1f * left + 0.1f * right);
//view::third_person::apply_translation(forward, strafe, 0);
collision_scene::update(up, down, left, right,
w, s, a, d);
w, s, a, d,
t, g, f, h,
i, k, j, l);
}
const int max_joysticks = 8;