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collision: ray aabb

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This commit is contained in:
Zack Buhman 2026-03-13 19:46:18 -05:00
parent 84fbd05841
commit ee3179899d
6 changed files with 142 additions and 30 deletions
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57
include/collision.h
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@ -1,5 +1,8 @@
#pragma once
#include <float.h>
#include <stdio.h>
#include "directxmath/directxmath.h"
namespace collision {
@ -9,6 +12,11 @@ namespace collision {
XMVECTOR max;
};
struct Sphere {
XMVECTOR center;
float radius;
};
static inline AABB cube_aabb(XMVECTOR const & center, float half)
{
half = fabsf(half);
@ -22,4 +30,53 @@ namespace collision {
return XMVectorClamp(p, aabb.min, aabb.max);
}
static inline bool test_sphere_aabb(Sphere const & sphere, AABB const & aabb, XMVECTOR & point)
{
point = closest_point_point_aabb(sphere.center, aabb);
XMVECTOR v = point - sphere.center;
return XMVectorGetX(XMVector3Dot(v, v)) <= sphere.radius * sphere.radius;
}
static inline void vector_swap_control(XMVECTOR & a, XMVECTOR & b, XMVECTOR const & control)
{
XMVECTOR tmp = XMVectorSelect(a, b, control);
b = XMVectorSelect(b, a, control);
a = tmp;
}
static inline bool intersect_ray_aabb(XMVECTOR const & point, XMVECTOR const & direction, AABB const & aabb, float & t_result, XMVECTOR & v_result)
{
// check parallel
XMVECTOR parallel = XMVectorLess(XMVectorAbs(direction), XMVectorSplatEpsilon());
XMVECTOR point_lt_aabb = XMVectorLess(point, aabb.min);
XMVECTOR point_gt_aabb = XMVectorGreater(point, aabb.max);
if (XMVectorGetX(parallel) != 0) // if (x < epsilon)
if (XMVectorGetX(point_lt_aabb) != 0 || XMVectorGetX(point_gt_aabb) != 0)
return false; // direction x is parallel and point x outside aabb
if (XMVectorGetY(parallel) != 0) // if (y < epsilon)
if (XMVectorGetY(point_lt_aabb) != 0 || XMVectorGetY(point_gt_aabb) != 0)
return false; // direction y is parallel and point y outside aabb
if (XMVectorGetZ(parallel) != 0) // if (z < epsilon)
if (XMVectorGetZ(point_lt_aabb) != 0 || XMVectorGetZ(point_gt_aabb) != 0)
return false; // direction z is parallel and point z outside aabb
XMVECTOR direction_reciprocal = XMVectorReciprocalEst(direction);
XMVECTOR t1 = (aabb.min - point) * direction_reciprocal;
XMVECTOR t2 = (aabb.max - point) * direction_reciprocal;
vector_swap_control(t2, t1, XMVectorGreater(t1, t2));
float tmin = XMVectorGetX(t1);
if (XMVectorGetY(t1) > tmin) tmin = XMVectorGetY(t1);
if (XMVectorGetZ(t1) > tmin) tmin = XMVectorGetZ(t1);
float tmax = XMVectorGetX(t2);
if (XMVectorGetY(t2) < tmax) tmax = XMVectorGetY(t2);
if (XMVectorGetZ(t2) < tmax) tmax = XMVectorGetZ(t2);
if (tmin > tmax) return false; // no intersection
t_result = tmin;
v_result = point + direction * tmin;
return true;
}
}

3
include/collision_scene.h
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@ -3,5 +3,6 @@
namespace collision_scene {
void load();
void draw();
void update(int up, int down, int left, int right);
void update(int up, int down, int left, int right,
int w, int s, int a, int d);
}

3
include/test.h
View File

@ -6,7 +6,8 @@ extern "C" {
void load(const char * source_path);
void draw();
void update_keyboard(int up, int down, int left, int right);
void update_keyboard(int up, int down, int left, int right,
int w, int s, int a, int d);
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,

9
main.lua
View File

@ -11,7 +11,8 @@ function init()
void load(const char * source_path);
void update_window(int width, int height);
void draw();
void update_keyboard(int kbup, int kbdown, int kbleft, int kbright);
void update_keyboard(int up, int down, int left, int right,
int w, int s, int a, int d);
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,
@ -61,7 +62,11 @@ local update = function(time)
local down = love.keyboard.isDown("down")
local left = love.keyboard.isDown("left")
local right = love.keyboard.isDown("right")
test.update_keyboard(up, down, left, right);
local w = love.keyboard.isDown("w")
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);
test.update(time)
end

94
src/collision_scene.cpp
View File

@ -27,6 +27,9 @@ namespace collision_scene {
static unsigned int index_buffer;
static XMVECTOR point_position;
static XMVECTOR point_1_position;
static unsigned int ray_vertex_buffer;
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wnarrowing"
@ -148,6 +151,23 @@ namespace collision_scene {
load_index_buffer();
point_position = XMVectorSet(0, 0, 0, 1);
point_1_position = XMVectorSet(0, 0, 0, 1);
// ray buffer
glGenBuffers(1, &ray_vertex_buffer);
}
void load_ray_vertex_buffer(XMVECTOR const & a, XMVECTOR const & b)
{
_Float16 data[] = {
(_Float16)XMVectorGetX(a), (_Float16)XMVectorGetY(a),
(_Float16)XMVectorGetX(b), (_Float16)XMVectorGetY(b),
};
glBindBuffer(GL_ARRAY_BUFFER, ray_vertex_buffer);
glBufferData(GL_ARRAY_BUFFER, 2 * 4, data, GL_DYNAMIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, 0);
}
static inline XMMATRIX view()
@ -163,13 +183,19 @@ namespace collision_scene {
return XMMatrixOrthographicRH(10, 10, 0, 10);
}
void update(int up, int down, int left, int right)
void update(int up, int down, int left, int right,
int w, int s, int a, int d)
{
float rate = 0.1f;
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);
point_position = XMVector3Transform(point_position, XMMatrixTranslation(strafe, forward, 0));
point_1_position = XMVector3Transform(point_1_position, XMMatrixTranslation(strafe_1, forward_1, 0));
}
static inline void set_transform(XMMATRIX const & transform)
@ -179,6 +205,33 @@ namespace collision_scene {
glUniformMatrix4fv(location.uniform.transform, 1, false, (float *)&float_transform);
}
const int circle_base_vertex = 8;
const int circle_base_index = 5 * (sizeof (unsigned short));
void draw_line(XMMATRIX const & transform, XMVECTOR const & a, XMVECTOR const & b)
{
load_ray_vertex_buffer(a, b);
set_transform(transform);
glBindVertexBuffer(0, ray_vertex_buffer, 0, per_vertex_size);
glDrawArrays(GL_LINES, 0, 4);
}
void draw_sphere(XMMATRIX const & transform, XMVECTOR const & center, float radius)
{
XMMATRIX sphere_transform
= XMMatrixScaling(radius, radius, radius)
* XMMatrixTranslationFromVector(center)
* transform;
set_transform(sphere_transform);
glBindVertexBuffer(0, per_vertex_buffer, 0, per_vertex_size);
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()
{
glUseProgram(program);
@ -216,31 +269,24 @@ namespace collision_scene {
glDrawElementsBaseVertex(GL_LINE_STRIP, 5, GL_UNSIGNED_SHORT, (void*)(cube_base_index), cube_base_vertex);
// circle
const int circle_base_vertex = 8;
const int circle_base_index = 5 * (sizeof (unsigned short));
const float point_radius = 0.05f;
XMMATRIX point_scale = XMMatrixScaling(0.05, 0.05, 0.05);
// point
glUniform3f(location.uniform.base_color, 1.0, 0.5, 0.0);
draw_sphere(transform, point_position, point_radius);
draw_sphere(transform, point_1_position, point_radius);
XMMATRIX point_transform
= point_scale
* XMMatrixTranslationFromVector(point_position)
* transform;
set_transform(point_transform);
glDrawElementsBaseVertex(GL_LINE_STRIP, 33, GL_UNSIGNED_SHORT, (void*)(circle_base_index), circle_base_vertex);
// closest point
glUniform3f(location.uniform.base_color, 1.0, 0.0, 0.0);
XMVECTOR direction = XMVector3Normalize(point_1_position - point_position);
collision::AABB cube_aabb = collision::cube_aabb(cube_position, cube_half);
XMVECTOR closest_point_position = collision::closest_point_point_aabb(point_position, cube_aabb);
XMMATRIX closest_point_transform
= point_scale
* XMMatrixTranslationFromVector(closest_point_position)
* transform;
set_transform(closest_point_transform);
glDrawElementsBaseVertex(GL_LINE_STRIP, 33, GL_UNSIGNED_SHORT, (void*)(circle_base_index), circle_base_vertex);
XMVECTOR intersection_point;
float t;
bool intersection = intersect_ray_aabb(point_position, direction, cube_aabb, t, intersection_point);
if (intersection && t > 0.0f) {
glUniform3f(location.uniform.base_color, 0.9, 0.0, 0.0);
draw_line(transform, point_position, intersection_point);
draw_sphere(transform, intersection_point, point_radius);
} else {
glUniform3f(location.uniform.base_color, 0.5, 0.5, 0.5);
draw_line(transform, point_position, point_position + direction * 20.0f);
}
}
}

6
src/test.cpp
View File

@ -287,12 +287,14 @@ void load(const char * source_path)
collision_scene::load();
}
void update_keyboard(int up, int down, int left, int right)
void update_keyboard(int up, int down, int left, int right,
int w, int s, int a, int d)
{
//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);
collision_scene::update(up, down, left, right,
w, s, a, d);
}
const int max_joysticks = 8;