I was wondering if there is a way to copy the rotational information of a sprite into a plane. It seems that for the sprite the rotation is set within the material and it is just one value. I tried copying the matrix of the sprite into that of the plane but had no luck.
Sprite rotation is defined in WebGL as you can read in SpritePlugin.js. Thus, if you wish to copy the rotation of an existing sprite in your scene, the easiest way may be to use quaternion. They allow better defining than x/y/z-angle defined ones (Euler rotations) as they ask for the rotation axis and the angle value. In your context, at each camera movement you modify a quaternion. You set it with quaternion.setFromAxisAngle(axis,angle). Then apply it to the plane with plane.setRotationFromQuaternion(quaternion).
Math side :
The axis would be the cross product between the vectors lastCameraPosition-sprite.position and actualCameraPosition-sprite.position,
the angle, the one between those vectors, got with the acos of their dot product divided by the product of their lengths.
For more about those maths, functions getMouseProjectionOnBall and rotateCamera in TrackBallControls are of great interest.
Hope it helped !
Related
In rgl, you can set up camera direction with rgl.viewpoint. It accepts theta, phi: polar coordinates. They specify the position of the camera looking at the origin. However, there is yet another one degree of freedom: angle of rotation of the camera along "eye" vector. I.e. one can imagine two vectors associated with camera: "eye" vector and "up" vector; theta and phi allow one to adjust "eye" vector, but I want then to adjust "up" vector after it. Is it possible to do it?
I guess that it can be possible to do it with userMatrix parameter («4x4 matrix specifying user point of view»), but I found no information how to use it.
The ?par3d help topic documents the rendering process in the "Rendering" section. It's often tricky to accomplish what you're asking for, but in this case it's not too hard:
par3d(userMatrix = rotationMatrix(20*pi/180, 0,0,1)
%*% par3d("userMatrix"))
will rotate by 20 degrees around the user's z-axis, i.e. line of sight.
I'm trying to generate height-map for spherical planet with perlin noise. How can I make it with seamless left/right borders? I smoothed heightmap in poles, but cannot understand how can I loop left and right sides.
This is how my textures look liked for now:
Mirroring (by y-axis)
This is great for making seamless background textures. But as you mentioned the texture must not contain distinct patterns otherwise it would be obvious. This can be used as a start point for texture generator
Morphing
There are vector and raster morphs out there depend on the content of image. You can try to use simple raster morph done by Linear interpolation (if resolution is the same which is your case) but this can make the texture blurry which can be disturbing on some images. For starters you can try to morph texture and its mirror together:
This is cosine weight distribution (50%:50% on sides and 100%:0% in the middle):
This is constant weight distribution (50%:50%):
adjusted texture generators
You can adjust your current texture generator to render seamlessly
create/use seamless texture background (created by #1,#2 or even #3)
add random number of random features with looped x axis
so if x is going out from the left it will go in from the right ...
x' = x%xs where xs is texture x-resolution
After modifying my main camera's projection matrix, the ScreenPointToRay method that use ray casting begin to fail, so the method which detect touched object use raycast fail too. Is there any way to use ScreenPointToRay method with a custom camera projection matrix?
If you made a custom camera projection matrix, then you probably know where is the user pointing to, how about casting a ray yourself and not using the helper?
If you have a problem with translation of the cursor to world position, there is a good approximation - take four angles on approxiamtely the edges of your camera's viewpoint (top of the viewport horizontal center, left of the viewport vertical center etc.) and interpolate between them.
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!)
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).