I'm fairly new to three.js. I've been playing around with constructing a rough terrain object by manipulating the vertices of a plane. I also map its UVs to an atlas of square textures.
I'm running into an issue where I have grey lines going across the plane in one direction. I've seen similar problems mentioned before, some mentioning that it was a problem with the CanvasRenderer, and that overdraw: true was the appropriate fix. I am using the WebGL renderer (I tried overdraw: true anyways, but that didn't have any effect).
When I cut out my UV manipulation, the lines disappear. Below is the code I use to manipulate the UVs, where the biomeTerrains[biome][#] returns Vector2 values.
for (var y = 0;y < rowLength-1;y++) {
for (var x = 0;x < rowLength-1;x++) {
var i = (x + (y * (rowLength-1))) * 2;
var biome = chunk.cells[x+','+y].biome;
geometry.faceVertexUvs[0][i] = [biomeTerrains[biome][0],biomeTerrains[biome][1],biomeTerrains[biome][3]];
geometry.faceVertexUvs[0][i+1] = [biomeTerrains[biome][1],biomeTerrains[biome][2],biomeTerrains[biome][3]];
}
}
This is a screenshot of the resulting grey lines: http://i.imgur.com/r0BGKpT.png
I'd appreciate any ideas or advice on dealing with this issue.
I slept on it, and the explanation came to me while showering. It's not an artifacting issue, the problem is that my UV coordinates are overshooting their intended space, so the lines are the result of the next texture in the atlas spilling over. I tested this theory by squeezing the UVs in by a small, arbitrary amount, and the lines disappeared. Unfortunately this isn't an ideal solution, but I should be able to figure out something more exact based on this knowledge.
Related
I am trying to Slant/Skew a texture to create some shadows for my game.
I have read over this helpful answer that shows this can be done by passing a matrix to spriteBatch.Begin().
Because my linear algebra skills are not very developed, I am having some troubles meeting my desired results. I am hoping to skew my shadow so it looks similar to the following. Where the shadow is slanted by an angle, but the bottom of the shadow lines up with the (feet in this case) bottom of the sprite.
I originally tied the skew matrix provided in the solution above:
Matrix skew = Matrix.Identity;
skew.M12 = (float)Math.Tan(MathHelper.ToRadians(36.87f));
But this ends up rotation the shadow against the world's origin. I see the solution also notes this, and provides the follow to rotate again the sprite.
Matrix myMatrix = Matrix.CreateTranslation(-100, -100, 0)
* Matrix.CreateScale(2f, 0.5f, 1f)
* Matrix.CreateTranslation(100, 100, 0);
Though I'm not sure where to apply this myMatrix Matrix. I have tried applying it to both the shadow sprite, the castingShadow sprite, and also multiplying them together and applying to the shadow with no luck.
I have also tried using other methods like Matrix.CreateRotationX(MathHelper.ToRadians(0.87f)) with no luck.
There is actually a Matrix.CreateShadow() method too, but it requires a Plane, which I have no semblance of in my game.
Can anyone can help me figure out the required Matrix for this slanting, or point me in the direction of some resources?
Thanks!
Okay, so I found a transform to use to get the desired slant.
Thanks to #David Gouveia and #AndreRussell from this post
Matrix matrix = Matrix.CreateRotationX(MathHelper.ToRadians(60)) *
Matrix.CreateRotationY(MathHelper.ToRadians(30)) *
Matrix.CreateScale(1,1,0);
EDIT:
So the above solution solved how I wanted to slant my texture, but had some weird positioning side effects. To address this, I ended up with a transform like the following:
Matrix slant = Matrix.CreateTranslation(-loc.X + angleX, -loc.Y, 0f) *
Matrix.CreateRotationX(MathHelper.ToRadians(angleX)) *
Matrix.CreateRotationY(MathHelper.ToRadians(30)) *
Matrix.CreateScale(1.4f, 1f, 0) *
Matrix.CreateTranslation(loc.X + angleX, loc.Y, 0f);
Where angleX was set based on the "sun" X position and loc vector is where I want the object and object's shadow to appear.
I want to have a DOM node track a particle in my THREE.js simulation. My simulation is built with the Points object, using a bufferGeometry. I'm setting the positions of each vertex in the render loop. Over the course of the simulation I'm moving / rotating both the camera and the Points object (through its parent Object3d).
I can't figure out how to get reliable screen coordinates for any of my particles. I've followed the instructions on other questions, like Three.JS: Get position of rotated object, and Converting World coordinates to Screen coordinates in Three.js using Projection, but none of them seem to work for me. At this point I can see that the calculated projections of the vertices are changing with my camera movements and object rotations, but not in a way that I can actually map to the screen. Also, sometimes two particles that neighbor each other on the screen will yield wildly different projected positions.
Here's my latest attempt:
const { x, y, z } = layout.getNodePosition(nodes[nodeHoverTarget].id)
var m = camera.matrixWorldInverse.clone()
var mw = points.matrixWorld.clone()
var p = camera.projectionMatrix.clone()
var modelViewMatrix = m.multiply(mw)
var position = new THREE.Vector3(x, y, z)
var projectedPosition = position.applyMatrix4(p.multiply(modelViewMatrix))
console.log(projectedPosition)
Essentially I've replicated the operations in my shader to derive gl_Position.
projectedPosition is where I'd like to store the screen coordinates.
I'm sorry if I've missed something obvious... I've tried a lot of things but so far nothing has worked :/
Thanks in advance for any help.
I figured it out...
var position = new THREE.Vector3(x, y, z)
var projectedPosition = position.applyMatrix4(points.matrixWorld).project(camera)
I'm trying to plot country names of the globe, so the text meshes will be aligned with the surface, but I'm failing to calculate proper rotations. For text I'm using THREE.TextGeometry. The name appears on the click of the mesh of the country at the point of intersection using raycasting. I'm lacking knowledge of how to turn these coordinates to proper rotation angles. I'm not posting my code, as it's complete mess and I believe for a knowldgeable person will be easier to explain how to achieve this in general.
Here is desired result:
The other solution, which I tried (and which, of course, is not the ultimate), based on this SO answer. The idea is to use the normal of the face you intersect with the raycaster.
Obtain the point of intersection.
Obtain the face of intersection.
Obtain the normal of the face (2).
Get the normal (3) in world coordinates.
Set position of the text object as sum of point of intersection (1) and the normal in world coordinates (4).
Set lookAt() vector of the text object as sum of its position (5) and the normal in world coordinates (4).
Seems long, but actually it makes not so much of code:
var PGHelper = new THREE.PolarGridHelper(...); // let's imagine it's your text object ;)
var PGlookAt = new THREE.Vector3(); // point of lookAt for the "text" object
var normalMatrix = new THREE.Matrix3();
var worldNormal = new THREE.Vector3();
and in the animation loop:
for ( var i = 0; i < intersects.length; i++ ) {
normalMatrix.getNormalMatrix( intersects[i].object.matrixWorld );
worldNormal.copy(intersects[i].face.normal).applyMatrix3( normalMatrix ).normalize();
PGHelper.position.addVectors(intersects[i].point, worldNormal);
PGlookAt.addVectors(PGHelper.position, worldNormal);
PGHelper.lookAt(PGlookAt);
}
jsfiddle exmaple
The method works with meshes of any geometry (checked with spheres and boxes though ;) ). And I'm sure there are another better methods.
very interesting question.I have tried this way, we can regard the text as a plane. lets define a normal vector n from your sphere center(or position) to point on the sphere surface where you want to display text. I have a simple way to make normal vector right.
1. put the text mesh on sphere center. text.position.copy(sphere.position)
2. make text to the point on sphere surface, text.lookAt(point)
3.relocate text to the point. text.position.copy(point)
I'm trying to set the ProjectionMatrix of a Three.js Perspective Camera to match a projection Matrix I calculated with a different program.
So I set the camera's position and rotation like this:
self.camera.position.x = 0;
self.camera.position.y = 0;
self.camera.position.z = 142 ;
self.camera.rotation.x = 0.0;// -0.032
self.camera.rotation.y = 0.0;
self.camera.rotation.z = 0;
Next I created a 4x4 Matrix (called Matrix4 in Three.js) like this:
var projectionMatrix = new THREE.Matrix4(-1426.149, -145.7176, -523.0170, 225.07519, -42.40711, -1463.2367, -23.6839, 524.3322, -0.0174, -0.11928, -0.99270, 0.43826, 0, 0, 0, 1);
and changed the camera's projection Matrix entries like this:
for ( var i = 0; i < 16; i++) {
self.camera.projectionMatrix.elements[i] = projectionMatrix.elements[i];
}
when I now render the scene I just get a black screen and can't see any of the objects I inserted. Turning the angle of the Camera doesn't help either. I still can't see any objects.
If I insert a
self.camera.updateProjectionMatrix();
after setting the camera's projection Matrix to the values of my projectionMatrix the camera is set back to the original Position (x=0,y=0,z=142 and looking at the origin where I created some objects) and the values I set in the camera's matrix seem to have been overwritten. I checked that by printing the cameras projection Matrix to the console. If I do not call the updateProjectionMatrix() function the values stay as I set them.
Does somebody have an idea how to solve this problem?
If I do not call the updateProjectionMatrix() function the values stay as I set them.
Correct, updateProjectionMatrix() calculates those 16 numbers you pasted in your projection matrix based on a bunch of parameters. Those parameters are, the position and rotation you set above, plus the parameters you passed (or default) for the camera. (these actually make the matrixWorld and its inverse.
In case of a perspective camera, you don't have much - near, far, fov and aspect. Left,right,top,bottom are derived from these, with an orthographic camera you set them directly. These are then used to compose the projection matrix.
Scratch a pixel has a REALLY good tutorial on this subject. The next lesson on the openGL projection matrix is actually more relevant to WebGL. left right top and bottom are made from your FOV and your aspect ratio. Add near and far and you've got yourself a projection matrix.
Now, in order for this thing to work, you either have to know what you're doing, or get really lucky. Pasting these numbers from somewhere else and getting it to work is short of winning the lottery. Best case scenario, you can have your scale all wrong and clipping your scene. Worst case, you've mixed a completely different matrix, different XYZ convention, and there's no way you'll get it to work, or at least make sense.
Out of curiosity, what are you trying to do? Are you trying to match your camera to a camera from somewhere else?
I've searched far and wide, so if there's a similar question please forgive me but I just couldn't find it.
To put what I'm trying to do in context: I want to create an infinitely-generated field of stars that disappear as they go offscreen and reappear at the edge of the screen where the camera is moving. I'm working with a top-down view, so it must be pretty simple to achieve this, but alas I haven't a clue.
I'm using the following code to determine whether a star has gone off-screen and then replace it:
//update camera frustum
camera.projScreenMatrix.multiplyMatrices(
camera.projectionMatrix,
camera.matrixWorldInverse
);
camera.frustum.setFromMatrix(camera.projScreenMatrix);
//loop through stars
var stars=scene.stars.geometry.vertices;
for(var i=0;i<stars.length;i++) {
if(!camera.frustum.containsPoint(stars[i])) {
stars[i]=new THREE.Vector3(
// fill in the blank
);
scene.stars.geometry.verticesNeedUpdate=true;
}
}
Since I'm using a perspective camera, I know I'll need to somehow factor in camera.fov and other perspective elements, but as you can tell I'm no expert on the third dimension.
Assuming I have an angle or normalized vector telling me the direction the view is panning, how would I go about creating a vertex along the edge of the screen regardless of its Z position?
If I'm not clear enough, I'll be happy to clarify. Thanks.
I know this is an old question, but I came across it while looking for an answer and found a simple, trigonometry reliant method to get the left edge of the camera frustum, and I'm sharing it in case someone else might find it useful:
// Get half of the cameras field of view angle in radians
var fov = camera.fov / 180 * Math.PI / 2;
// Get the adjacent to calculate the opposite
// This assumes you are looking at the scene
var adjacent = camera.position.distanceTo( scene.position );
// Use trig to get the leftmost point (tangent = o / a)
var left = Math.tan( fov ) * adjacent * camera.aspect;
Basically, this gets the leftmost point, but if you don't multiply by the aspect ratio you should get a point in a circle around your camera frustum, so you could translate a point any direction away from the cameras focus and it would always be outside the frustum.
It works by assuming that the imaginary plane that is the camera is perpendicular to the line connecting the camera and its focus, so there is a straight angle. This should work if you want objects further away as well (so if you want them at a further point from the camera you just need to increase the distance between the focus and the camera).
Well, countless headaches and another question later, I've come up with a fairly makeshift answer. Just in case by some unlikely chance someone else has the same question, the following function plots a point on the scene relative to the camera's current view with whatever Z specified:
//only needs to be defined once
var projector=new THREE.Projector();
//input THREE.Vector3
function(vector) {
var z=vector.z;
vector.z=0;
projector.unprojectVector(vector,camera);
return camera.position.clone().add(
vector
.sub(camera.position)
.normalize()
.multiplyScalar(
-(camera.position.z-z)/vector.z
)
);
The x and y, in this case, both range from -1 to 1 for bottom-left to top-right. You can use position/window.Width and position/window.Height for extra precision (using mouse coordinates or what have you).