I have an a cubecamera at (0,0,0) as well as a giant sphere around it (textured on the inside).
The cubecamera creates a cubemap which is applied as the environment map for a second, smaller sphere.
When the second sphere moves on the screen its environment map reflection also moves.
My question is why does it move?
I am using an orthographic camera so I am always looking at the
smaller sphere flat on, even if it moves left/right.
The cubecamera is the source of the environment map and the
cubecamera does not move.
The giant sphere which the cubecamera builds its map from also does
not move.
Environment mapping is a projection from the environment to your object, here the small sphere. So if the object changes position the mapping changes also. It does not matter it you are projecting using an orthographic camera or a perspective camera. It is still a positional based mapping.
Related
I'm trying to add clouds to my scene using the approach in https://codepen.io/teolitto/pen/KwOVvL, which is to make a large number of plane objects at random positions that each rotate continuously around their z axes.
But I would like to be able to move my camera, change its target, etc., and still have the cloud planes look right.
What I need to do is rotate the planes so that as the camera moves and changes target, the cloud planes stay perpendicular to the camera's axis. And I need to do this without changing the planes' rotation around their own z-axis, because otherwise that would break the cloudlike appearance.
I've tried cloudplane.lookAt(camera.position) but of course that doesn't work. It aims all of the planes at the camera, instead of making them all perpendicular to the camera axis. It also sets the object's z-axis, so the clouds don't evolve.
Any advice is appreciated. (I'm new to three.js, so if I have some of the terminology wrong, I apologize for that.)
Edit:
Setting the cloudplane's rotation.x and rotation.y to match the camera's rotation.x and rotation.y seems to get me pretty close, but it doesn't quite get there - its still possible to orbit the camera to a position where the clouds are all invisible because they're all parallel to the camera.
I have some project for child http://kinosura.kiev.ua/sova/ and i need to check faceIndex of all cubes in screen.
Now i use intersections array from mouse, but is working only when user pointer at the cube.
How to make ray or rays from camera to all object to check faceIndex ?
I try to make four rays to cubes but if i set cube.position as origin of like this:
raycaster.setFromCamera( cube1.positoin , camera )
I get empty array of intersections.
I also try to set static 2d vector as origin (get coordinate from mouse) but i have relative renderer size and this coordinate all time change... its not work(
Thanks for answer anyway.
I suggest that you try another approach It appears that your cubes do not cover one another, relative to the camera view. So use the surface normals, and compare them to the view direction to determine if they are facing the camera or facing away from the camera by a simple one-per-polygon dot product.
When you are creating your geometry, before adding it a THREE.Mesh call .generateFaceNormals() on it.
Instead of ray casting, iterate through all faces, grab the surface normal of the face, transform relative to the view (inverse transpose of the object's matrix), then dot(). might sound complicated, at first, but it's actually just a couple of steps and much faster than doing a lot of raycasts (which will probably include this anyway!)
I'm quite new to three.js and lacking some basic understanding of the coordinate systems obviously.
I have an Object3D "group" that has some children (planes). I use "group" to rotate the group of planes, which works fine. Now camera can move and parent object can rotate. One can click on the planes to select them. What I want now is to let the selected plane fly into the camera.
If I just move the plane to the camera position it flys in any direction but mostly not to the camera. Certainly because "group" seems to be the "world" for the child objects. If I move a plane along the z-axis the plane move along the z-axis of the parent.
I don't understand which coordinates I need to take (or transform) to move the plane bound to "group" in front of the camera.
Basically I demoed with three.js what famo.us did, just spent some two hours on it or so. I faked the wanted effect with an additional plane that is not grouped and which I can just move to camera without transformations. The demo is available here:
http://hwg.rattat.net/famo.html.
Would be nice if somebody could tell me how to get this working. I could still live with the fake, when I would be able to place the additional plane exactly over the selected plane.
Thanks in advance,
Christian
The question of converting local coordinates to world coordinates has been addressed at THREE.js: Calculate world space position of a point on an object . There might also be helping information at how to: get the global/world position of a child object .
Say I have a simple triangle as the only element/child in an Object3D class. I have a PerspectiveCamera looking at it, and I would like to have the Object3D travel down the camera's positive X axis, say, when I press a key.
How can I manipulate things so that the Object3D travels parallel along the camera's X axis? In looking at the inner workings of the PerspectiveCamera, I see members for things like matrixWorld and matrixWorldInverse but am not sure what they represent or how best to use them here.
Can I use the camera's matrixWorldInverse matrix to get the Object3D into camera coordinates, then move the object along the camera's x-axis (which I'm not sure how to find, as I don't see an entry for it in PerspectiveCamera, though I may not be seeing it) then multiply the Object3D by the 'matrixWorld' matrix again to move it back to world coordinates?
Have you tried making your object a child of your camera? Then any movement of the camera would affect your object. And if you place the camera lets say on the y-z plane of your object, then any movement of the object on its x-axis will also appear to be on the x-axis of the camera.
Context: trying to take THREE.js and use it to display conic sections.
Method: creating a mesh of vertices and then connect face4's to all of them. Used two faces to produce a front and back side so that when the conic section rotates it won't matter from which angle the camera views it.
Problems encountered: 1. Trying to find a good way to create a intuitive mouse rotation scheme. If you think in spherical coordinates, then it feels like just making up/down change phi and left/right change phi would work. But that requires that you can move the camera. As far as I can tell, there is no way to change actively change the rotation of anything besides the objects. Does anyone know how to change the rotation of the camera or scene? 2. Is there a way to graph functions that is better than creating a mesh? If the mesh has many points then it is too slow, and if the mesh has few points then you cannot easily make out the shape of the conic sections.
Any sort of help would be most excellent.
I'm still starting to learn Three.js, so I'm not sure about the second part of your question.
For the first part, to change the camera, there is a very good way, which could also include zooming and moving the scene: the trackball camera.
For the exact code and how to use it, you can view:
https://github.com/mrdoob/three.js/blob/master/examples/webgl_trackballcamera_earth.html
At the botton of this page (http://mrdoob.com/122/Threejs) you can see the example in action (the globe in the third row from the bottom).
There is an orbit control script for the three.js camera.
I'm not sure if I understand the rotation bit. You do want to rotate an object, but you are correct, the rotation is relative.
When you rotate or move your camera, a matrix is calculated for that position/rotation, and it does indeed rotate the scene while keeping the camera static.
This is irrelevant though, because you work in model/world space, and you position your camera in it, the engine takes care of the rotations under the hood.
What you probably want is to set up an object, hook up your rotation with spherical coordinates, and link your camera as a child to this object. The translation along the cameras Z axis relative to the object should mimic your dolly (zoom is FOV change).
You can rotate the camera by changing its position. See the code I pasted here: https://gamedev.stackexchange.com/questions/79219/three-js-camera-turning-leftside-right
As others are saying OrbitControls.js is an intuitive way for users to manage the camera.
I tackled many of the same issues when building formulatoy.net. I used Morphing Geometries since I found mapping 3d math functions to a UV surface to require v little code and it allowed an easy way to implement different coordinate systems (Cartesian, spherical, cylindrical).
You could use particles instead of a mesh I suppose but a mesh seems best. The lattice material is not too useful if you're trying to understand a surface mathematically. At this point I'm thinking of drawing my own X,Y lines on the surface (or phi, theta lines etc) to better demonstrate cross-sections.
Hope that helps.
You can use trackball controls by which you can zoom in and out of an object,rotate the object,pan it.In trackball controls you are moving the camera around the object.Object still rotates with respect to the screen or renderer centre (0,0,0).