Javidx9
5 years ago
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/*
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One-Size-Fits-All Rectangle Vs Rectangle Collisions |
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"Stupid scanners... making me miss at archery..." - javidx9 |
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License (OLC-3) |
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~~~~~~~~~~~~~~~ |
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Copyright 2018-2020 OneLoneCoder.com |
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Redistribution and use in source and binary forms, with or without |
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modification, are permitted provided that the following conditions |
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are met: |
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1. Redistributions or derivations of source code must retain the above |
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copyright notice, this list of conditions and the following disclaimer. |
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2. Redistributions or derivative works in binary form must reproduce |
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the above copyright notice. This list of conditions and the following |
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disclaimer must be reproduced in the documentation and/or other |
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materials provided with the distribution. |
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3. Neither the name of the copyright holder nor the names of its |
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contributors may be used to endorse or promote products derived |
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from this software without specific prior written permission. |
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
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HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
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SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
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LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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Relevant Video: https://www.youtube.com/watch?v=8JJ-4JgR7Dg
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Links |
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~~~~~ |
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YouTube: https://www.youtube.com/javidx9
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https://www.youtube.com/javidx9extra
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Discord: https://discord.gg/WhwHUMV
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Twitter: https://www.twitter.com/javidx9
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Twitch: https://www.twitch.tv/javidx9
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GitHub: https://www.github.com/onelonecoder
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Patreon: https://www.patreon.com/javidx9
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Homepage: https://www.onelonecoder.com
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Community Blog: https://community.onelonecoder.com
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Author |
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~~~~~~ |
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David Barr, aka javidx9, ©OneLoneCoder 2018, 2019, 2020 |
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*/ |
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#define OLC_PGE_APPLICATION |
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#include "olcPixelGameEngine.h" |
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#include <algorithm> |
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#include <functional> |
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#undef min |
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#undef max |
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namespace olc |
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{ |
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namespace aabb |
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{ |
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struct rect |
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{ |
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olc::vf2d pos; |
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olc::vf2d size; |
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olc::vf2d vel; |
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std::array<olc::aabb::rect*, 4> contact; |
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}; |
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bool PointVsRect(const olc::vf2d& p, const olc::aabb::rect* r) |
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{ |
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return (p.x >= r->pos.x && p.y >= r->pos.y && p.x < r->pos.x + r->size.x && p.y < r->pos.y + r->size.y); |
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} |
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bool RectVsRect(const olc::aabb::rect* r1, const olc::aabb::rect* r2) |
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{ |
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return (r1->pos.x < r2->pos.x + r2->size.x && r1->pos.x + r1->size.x > r2->pos.x && r1->pos.y < r2->pos.y + r2->size.y && r1->pos.y + r1->size.y > r2->pos.y); |
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} |
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bool RayVsRect(const olc::vf2d& ray_origin, const olc::vf2d& ray_dir, const rect* target, olc::vf2d& contact_point, olc::vf2d& contact_normal, float& t_hit_near) |
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{ |
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contact_normal = { 0,0 }; |
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contact_point = { 0,0 }; |
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// Cache division
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olc::vf2d invdir = 1.0f / ray_dir; |
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// Calculate intersections with rectangle bounding axes
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olc::vf2d t_near = (target->pos - ray_origin) * invdir; |
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olc::vf2d t_far = (target->pos + target->size - ray_origin) * invdir; |
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if (std::isnan(t_far.y) || std::isnan(t_far.x)) return false; |
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if (std::isnan(t_near.y) || std::isnan(t_near.x)) return false; |
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// Sort distances
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if (t_near.x > t_far.x) std::swap(t_near.x, t_far.x); |
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if (t_near.y > t_far.y) std::swap(t_near.y, t_far.y); |
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// Early rejection
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if (t_near.x > t_far.y || t_near.y > t_far.x) return false; |
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// Closest 'time' will be the first contact
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t_hit_near = std::max(t_near.x, t_near.y); |
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// Furthest 'time' is contact on opposite side of target
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float t_hit_far = std::min(t_far.x, t_far.y); |
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// Reject if ray direction is pointing away from object
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if (t_hit_far < 0) |
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return false; |
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// Contact point of collision from parametric line equation
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contact_point = ray_origin + t_hit_near * ray_dir; |
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if (t_near.x > t_near.y) |
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if (invdir.x < 0) |
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contact_normal = { 1, 0 }; |
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else |
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contact_normal = { -1, 0 }; |
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else if (t_near.x < t_near.y) |
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if (invdir.y < 0) |
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contact_normal = { 0, 1 }; |
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else |
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contact_normal = { 0, -1 }; |
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// Note if t_near == t_far, collision is principly in a diagonal
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// so pointless to resolve. By returning a CN={0,0} even though its
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// considered a hit, the resolver wont change anything.
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return true; |
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} |
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bool DynamicRectVsRect(const olc::aabb::rect* r_dynamic, const float fTimeStep, const olc::aabb::rect& r_static, |
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olc::vf2d& contact_point, olc::vf2d& contact_normal, float& contact_time) |
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{ |
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// Check if dynamic rectangle is actually moving - we assume rectangles are NOT in collision to start
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if (r_dynamic->vel.x == 0 && r_dynamic->vel.y == 0) |
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return false; |
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// Expand target rectangle by source dimensions
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olc::aabb::rect expanded_target; |
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expanded_target.pos = r_static.pos - r_dynamic->size / 2; |
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expanded_target.size = r_static.size + r_dynamic->size; |
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if (RayVsRect(r_dynamic->pos + r_dynamic->size / 2, r_dynamic->vel * fTimeStep, &expanded_target, contact_point, contact_normal, contact_time)) |
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return (contact_time >= 0.0f && contact_time < 1.0f); |
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else |
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return false; |
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} |
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bool ResolveDynamicRectVsRect(olc::aabb::rect* r_dynamic, const float fTimeStep, olc::aabb::rect* r_static) |
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{ |
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olc::vf2d contact_point, contact_normal; |
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float contact_time = 0.0f; |
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if (DynamicRectVsRect(r_dynamic, fTimeStep, *r_static, contact_point, contact_normal, contact_time)) |
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{ |
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if (contact_normal.y > 0) r_dynamic->contact[0] = r_static; else nullptr; |
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if (contact_normal.x < 0) r_dynamic->contact[1] = r_static; else nullptr; |
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if (contact_normal.y < 0) r_dynamic->contact[2] = r_static; else nullptr; |
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if (contact_normal.x > 0) r_dynamic->contact[3] = r_static; else nullptr; |
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r_dynamic->vel += contact_normal * olc::vf2d(std::abs(r_dynamic->vel.x), std::abs(r_dynamic->vel.y)) * (1 - contact_time); |
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return true; |
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} |
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return false; |
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} |
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} |
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} |
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class RectangleCollisions : public olc::PixelGameEngine |
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{ |
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public: |
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RectangleCollisions() |
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{ |
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sAppName = "Rectangles!"; |
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} |
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std::vector<olc::aabb::rect> vRects; |
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public: |
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bool OnUserCreate() override |
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{ |
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vRects.push_back({ {170.0f, 70.0f}, {10.0f, 40.0f} }); |
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vRects.push_back({ {150.0f, 50.0f}, {20.0f, 20.0f} }); |
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vRects.push_back({ {150.0f, 150.0f}, {75.0f, 20.0f} }); |
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vRects.push_back({ {170.0f, 50.0f}, {20.0f, 20.0f} }); |
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vRects.push_back({ {190.0f, 50.0f}, {20.0f, 20.0f} }); |
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vRects.push_back({ {110.0f, 50.0f}, {20.0f, 20.0f} }); |
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vRects.push_back({ {50.0f, 130.0f}, {20.0f, 20.0f} }); |
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vRects.push_back({ {50.0f, 150.0f}, {20.0f, 20.0f} }); |
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vRects.push_back({ {50.0f, 170.0f}, {20.0f, 20.0f} }); |
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vRects.push_back({ {150.0f, 100.0f}, {10.0f, 1.0f} }); |
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vRects.push_back({ {200.0f, 100.0f}, {20.0f, 60.0f} }); |
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return true; |
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} |
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bool OnUserUpdate(float fElapsedTime) override |
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{ |
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Clear(olc::DARK_BLUE); |
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olc::vf2d vMouse = { float(GetMouseX()), float(GetMouseY()) }; |
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olc::vf2d vPoint = { 128.0f, 120.0f }; |
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if (GetKey(olc::Key::W).bHeld) vRects[0].vel.y = -100.0f; |
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if (GetKey(olc::Key::S).bHeld) vRects[0].vel.y = +100.0f; |
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if (GetKey(olc::Key::A).bHeld) vRects[0].vel.x = -100.0f; |
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if (GetKey(olc::Key::D).bHeld) vRects[0].vel.x = +100.0f; |
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if (GetMouse(0).bHeld) |
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vRects[0].vel += (vMouse - vRects[0].pos).norm() * 100.0f * fElapsedTime; |
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// Draw all rectangles
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for (const auto& r : vRects) |
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DrawRect(r.pos, r.size, olc::WHITE); |
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// Sort collisions in order of distance
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olc::vf2d cp, cn; |
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float t = 0, min_t = INFINITY; |
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std::vector<std::pair<int, float>> z; |
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// Work out collision point, add it to vector along with rect ID
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for (size_t i = 1; i < vRects.size(); i++) |
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{ |
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if (olc::aabb::DynamicRectVsRect(&vRects[0], fElapsedTime, vRects[i], cp, cn, t)) |
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{ |
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z.push_back({ i, t }); |
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} |
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} |
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// Do the sort
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std::sort(z.begin(), z.end(), [](const std::pair<int, float>& a, const std::pair<int, float>& b) |
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{ |
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return a.second < b.second; |
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}); |
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// Now resolve the collision in correct order
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for (auto j : z) |
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olc::aabb::ResolveDynamicRectVsRect(&vRects[0], fElapsedTime, &vRects[j.first]); |
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// Embellish the "in contact" rectangles in yellow
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for (int i = 0; i < 4; i++) |
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{ |
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if (vRects[0].contact[i]) |
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DrawRect(vRects[0].contact[i]->pos, vRects[0].contact[i]->size, olc::YELLOW); |
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vRects[0].contact[i] = nullptr; |
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} |
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// UPdate the player rectangles position, with its modified velocity
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vRects[0].pos += vRects[0].vel * fElapsedTime; |
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// Draw players velocity vector
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if (vRects[0].vel.mag2() > 0) |
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DrawLine(vRects[0].pos + vRects[0].size / 2, vRects[0].pos + vRects[0].size / 2 + vRects[0].vel.norm() * 20, olc::RED); |
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return true; |
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} |
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}; |
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int main() |
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{ |
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RectangleCollisions demo; |
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if (demo.Construct(256, 240, 4, 4, false, false)) |
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demo.Start(); |
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return 0; |
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} |
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