<script src="./rectangle_line/dist/output.js"></script> <script> window.onload = function() { var lPlayElement = document.getElementById('gl_canvas_play'), lStopElement = document.getElementById('gl_canvas_stop'); lPlayElement.addEventListener('click', function() { lPlayElement.style.display = 'none'; lStopElement.style.display = 'block'; }); lStopElement.addEventListener('click', function() { lStopElement.style.display = 'none'; lPlayElement.style.display = 'block'; }); } </script> <article> <h1>Rectangle intersection with a Line Segment</h1> <section> <h2>Algorithm</h2> <p> For each line segment that your rectangle could be intersecting with, do the following: <ol> <li> For each corner of your rectangle, check if the distance from that point to the line is less than some <i>epsilon</i>, where <i>epsilon</i> is a reasonable small number (usually a 1 or 2 units, depending on the size of your lines). </li> <li> To check each point, use the "distance from point to line segment" formula, which can be found <a href="https://en.wikipedia.org/wiki/Distance_from_a_point_to_a_line">here</a> (I will not derive it just yet) </li> <li> If a collision is found, we have all of the information required to solve the collision: <ul> <li> <b>Collision Normal</b>: This is the perpendicular to the line segment, which can be found by: <code> <pre> Vector2 getNormalToLineSegment(LineSegment* segment) { Vector2 direction = segment->end - segment->start; return *Vector2 { -direction.y, direction.x }).normalize(); } </pre> </code> </li> <li> <b>First Point of Application</b>: Get the vector from the center of the rectangle (most like your position) to the corner which intersected. </li> <li> <b>Second Point of Application</b>: Get vector from center of line to the corner which intersected. </li> </ul> </li> </ol> </p> </section> <section> <h2> Live Example </h2> <div class="opengl_canvas_container"> <canvas id="gl_canvas" width="800" height="600"></canvas> <button id="gl_canvas_play" class="play_button"> Play </button> <button id="gl_canvas_stop" class="stop_button"> Stop </button> </div> <footer id="references"> <h2>References</h2> <ul> <li><a href="https://en.wikipedia.org/wiki/Distance_from_a_point_to_a_line">Distance from Point to Line</a></li> </ul> </footer> </section> </article>