I create my frustum like this:
var frustum = new THREE.Frustum();
frustum.setFromMatrix(new THREE.Matrix4().multiply(camera.projectionMatrix, camera.matrixWorldInverse));
but the frustum planes property is just an array.
I need to get the specific planes of a frustum, ie what plane of the frustum planes is the near plane, far plane, etc... what order are they in?
Related
I am trying to draw a line segment from a point a 3D scene to point on a HUD UI. One end of the line segment is specified in 3D e.g. (1.232, -34.12, 4.21) but the other I want to specify in 2D pixel coordinates e.g. (320, 200).
How can I convert the 2D coordinate to a 3D point and have it remain at those pixel coordinates as the camera (Perspective) moves? Initially I thought of taking the 2D position and projecting it onto the near view frustum maybe that would work, but wasn't sure how to do it or if there was a better way?
var vector = new THREE.Vector3(320, 200, 0.5);
vector.unproject(camera);
will return in vector a 3D point which you can use to draw.
If you keep unprojecting as the perspective camera moves you are guaranteed that the 2D point will seem not to move in your HUD.
I have two spheres on which panoramic image is mapped. I want to make smooth transition between 2 panoramas with fade effect. for both panorama I have initial camera direction set for best view.
Now the issue is if user is looking at some camera angle in first panorama and then he clicks on some button to switch panorama I want to give fade effect and directly land on initial camera angle of another pano.
But as both pano are sharing common camera, I cannot play with camera to achieve it so I devised following solution -
image depicting problem
rotate target sphere so that it looks at desired camera direction.
rotate target sphere so that it looks at existing camera direction.
fadeout source sphere.
camera look at new panos camera direction.
rotate back pano to initial orientation.
Here I am not able to find formula of rotating panorama to look at camera. (like camera is static and pano is rotated to achieve similar effect as if we are moving camera).
Can somebody please help in finding formula to rotate pano(sphere) relative to camera.
Matrix is a very powerful tool to solve rotation problem. I made a simple to explain.
At the beginning, the camera is in the center of the left sphere and face to initial viewpoint, then, the camera face to another point, now, the camera's rotation has changed, next, camera move to the center of the right sphere and keep its orientation. and we need to rotate the right sphere. If C is the point that we want to make the camera to face, first, we rotate A to B， second, we rotate some angle θ equal to C to A.
So, how to do like that? I used matrix, because A is an initial point, matrix in an identity matrix, and the rotation from A to C can be represented by a matrix, calculated by three.js function matrix4.lookAt(eye,center,up) which 'eye' is the camera position, 'center' is coordinate of C, and 'up' is camera up vector. Then, rotation matrix from C to A is the inverse matrix of the matrix from A to C. Because the camera is face to B now, so the camera's matrix equals to the rotation matrix from A to B.
Finally, we put it all together, the final rotation matrix can be written in:rotationMatrix = matrixAtoB.multiply(new THREE.Matrix4().getInverse(matrixAtoC));
jsfiddle example.
This way is a matrix way, you can also solve the problem with the spherical polar system.
Thanks for the helps in advance.
Three.js Raycaster class allows sending rays from camera to the object. I want to achieve a reverse operation. Imagine that we have a plane in the scene which represents our screen for projection. We also have an object (mesh) to be projected. I'm trying to find where would a vertex be projected on the screen.
Practically, for a vertex, if we project a ray from vertex to camera, we need to find its intersection with the screen plane. Note that everything is in 3D here. So my screen(camera) plane is in 3D coordinates too.
Any advise to solve this problem?
I think what you are looking for is projection of an object3d to screen position.
It was answered here:
answer
then you will have vector2d with x,y screen coordinates.
if you want the point on an actual 3d plane, you can then make a ray from the camera to that position on the screen, add to the ray intersection only that plane you locate infront of the camera, and then get the intersection point:
rayCaster.setFromCamera(vector2d, camera);
var aIntersects = rayCaster.intersectObject(planeInFrontOfCamera);
if (aIntersects.length > 0) {
var positionOnPlane = aIntersects[0].point.
}
I would like to create a vertex shader in Three.js to render the faces of a textured geometry so that all the triangles are face-on to the camera.
This is to emulate the functionality and performance of Three.js Points, but without the size limitation of gl_PointSize.
I'm not really sure what calculation to perform in the vertex shader. Any help appreciated.
you will have to add custom attribute to your geometry, easiest one to use would be a vector to the center of the triangle
in vertex shader you will have to calculate how to move each vertex, you now have
vertex position
vector to center
vertex normal == face normal
camera orientation (from matrices)
from that you can calculate the triangle center, which be static and calculate the rotation vertex has to make around the triangle center around axis perpendicular to the vector to center so that normal will come out as inverse of the camera orientation
the math is not very complicated, but writing shader code is tedious because of the non-existent debug - i advise you to first write a code that rotates the positions of geometry(using only the same parametres) and port it to shader
I'm trying to make a rubik cube game in webgl using three.js (you can try it here).
And I have problems to detect on witch axis I have to rotate my cube according the rotation of the cube. For instance, if the cube is in original position/rotation, if I want to rotate the left layer from down to up, I must make a rotation on the Y axis. But I rotate my cube 90 degrees on Y, I will have to rotate It on the Z axis to rotate my left layer from down to up.
I'm trying to find a way to get the correct rotation axis according the orientation of the cube.
For the moment I check witch vector of the axis of the rotation matrix of the cube is most parallel with the vector(0,1,0) if I want to move a front layer from down to up. But it do not works in edge cases like this for instance :
I guess there is some simple way to do that, but I'm not good enough in matrix and mathematical stuff :)
An AxisHelper can show the aixs of the scene which you could determine the orientation with.
var axishelper = new THREE.AxisHelper(40);
axishelper.position.y = 300;
scene.add(axishelper);
You could also log your cube and check the position and rotation properties with Chrome Developer Tools or Firebug.
You can store the orientation of each cube in its own 4x4 matrix (i.e. a "model" matrix) that tells you how to get from the cube's local coordinates to the world's coordinates. Now, since you want to rotate the cube around to an axis (i.e. vector) in world coordinates, you need to translate the axis into cube coordinates. This is exactly what the inverse of the model matrix yields.