raycasting

问题 I'm trying to determine whether a point in space is visible to the camera or hidden behind other objects in the scene. I'm doing this by casting a ray from the position of the camera to that point in space and testing if that ray is intersected by an set of intersectable objects. My problem is no intersections occur until the camera position itself intersects one of the objects in the set of intersectable objects. I've created a jsfiddle in which, if an intersection is detected, a line is

问题 The output looks like this: You should just see a flat, continuous red wall on one side, blue wall on another, green on another, yellow on another (see the definition of the map, testMapTiles , it's just a map with four walls). Yet there are these phantom wall faces of varying height, which are perpendicular to the real walls. Why? Note that the white "gaps" aren't actually gaps: it's trying to draw a wall of height Infinity (distance 0). If you specifically account for it (this version of

问题 I'm making a simple building system using Raycasting from the mouse pointer. The object that is to be placed is moved (and cloned on click) to the RaycastHit.point of the ray, but I want it to fully collide with objects of its own type, shifting its position relative to the hit point. The object can intersect the terrain as shown in the gif, but should not be inside of the already placed wall blocks. I tried using hit.distance but couldn't figure the detection out, since the object is being

问题 I want to create a 2D plane centered on 0,0,0 in 3D world space. Then, I want to define this plane in 2d tile coordinates. So e.g. a plane divided by 3 tiles would become a map of an array [3,3] The issue is that this would still give a tilemap with negative points. The world upper left -1,1 would be 0,0 in the array -1,- would be 1,0 and so on... World: -1,1 0,1 1,1 -1,0 0,0 1,0 -1,-1 0,-1 1,-1 Array: 0,0 0,1 0,2 1,0 1,1 1,2 2,0 2,1 2,2 My main hope with Unity was that I could avoid the math

问题 I am trying to make a 2d plat-former where you see the player from the side. I want him to be continuously moving and you have to press space at the right time so he doesn't fall. Right now everything works but he doesn't collide with the ground. I want it to be like he's running behind a wall so I want to ignore a certain layer I have made and collide with the boxes below that. So far I have tried ray casting, watched multiple tutorials, and did box collisions. Box collisions worked but to

来源： https://stackoverflow.com/questions/18805206/sfml-drawing-pixel-array

来源： https://stackoverflow.com/questions/54842920/arkit-raycasting-using-a-world-ray-instead-of-a-screen-point

问题 I know how to compute a ray-plane intersection, but how can I test if the intersection point is within a square on that plane? I was testing if the point was within a distance from the center of the square but I'm not sure if this is correct. 回答1: Here is a method that works for any convex polygon: (see simplified version for squares at the end of answer) Let p1,p2,p3,p4 denote the four vertices of your square and let q denote the intersection between the ray and the supporting plane. Let n

问题 I've put together a WebGL script that displays several meshes using jsonloader and three.js and I now want to add MouseOver and onClick events. The first of these is simply changing the colour of the mesh when the mouse hovers over it: function render() { requestAnimationFrame(render); mesh.rotation.z += 0.090; raycaster.setFromCamera(mouse, camera); var intersects = raycaster.intersectObjects(scene.children); for (var i = 0; i < intersects.length; i++) { intersects[i].object.material.color

问题 I'm rendering some custom layers using Three.js in a Mapbox GL JS page following this example. I'd like to add raycasting to determine which object a user has clicked on. The issue is that I only get a projection matrix from Mapbox, which I use to render the scene: class CustomLayer { type = 'custom'; renderingMode = '3d'; onAdd(map, gl) { this.map = map; this.camera = new THREE.Camera(); this.renderer = new THREE.WebGLRenderer({ canvas: map.getCanvas(), context: gl, antialias: true, }); this