I am working on a 3D mesh manipulator using this : http://leapmotion.com. So far, I have been able manipulate the points just fine, by 'grabbing' and moving them, however I now want to be able to rotate the mesh and work on the opposite face. What I have done is add an extra object that is called 'rotatable' as Shown below:
scene=new THREE.Scene();
camera = new THREE.PerspectiveCamera(70,window.innerWidth/window.innerHeight,1,8000)
renderer=new THREE.WebGLRenderer( { clearColor: 0x000000, clearAlpha: 1, maxLights:5 } )
//This is the 'Mesh Scene'
rotatable = new THREE.Object3D()
scene.add(rotatable)
//Mesh we are altering
var material = new THREE.MeshNormalMaterial()
material.side=2
var geom = new THREE.SphereGeometry(200,10,10);
var sphere = new THREE.Mesh(geom, material)
rotatable.add(sphere)
I am then trying to change the vertices of this sphere, but to do so I need to do a 'collision test' in order to see if the vertex is being 'grabbed' This involves check the vertex position and see if it coincides with one of your finger position (psuedoCode below)
if(finger.x == vertex.x && finger.y == vertex.y && finger.z == vertex.z){
vertex.grabbed = true
}
This works fine when the rotatable's rotation is zero, however when it starts to rotate, the collision test will still be testing for the unrotated vertex position (which makes sense). My question is how to find the position of the vertex in its 'scene / global' position. The only way I can think of doing this so far is to calculate the rotation of the 'rotatable' and use this vector to calculate the new vertex position.
I know nothing about math, so this may not be the way to go, and even if it is I will have to struggle through it so hard that I won't ever know if I'm just doing the math incorrectly, or this isn't the way I should go about calculating it. Obviously I'm willing to go through this work, but just want to make sure this is the way to do it, rather then an other simpler method.
If there are any other questions about the code, please let me know, and Thanks in advance for your time!
Isaac
To get the world position of a vertex specified in local coordinates, apply the object's world transform to the vertex like so:
vertex.applyMatrix4( object.matrixWorld );
(I am not familiar with leapmotion, so hopefully it does not impact this answer.)
Tip: maxLights is no longer required. And it is best to avoid material.side = 2. Use material.side = THREE.DoubleSide instead.
You can find the constants here: https://github.com/mrdoob/three.js/blob/master/src/Three.js
three.js r.55
Related
Iam nooby in godot, I have to use A* to traslate the player to the goal position, but I do not know how to start, pls help!! basically I have just 2 tiles in the tilemap, 1 of them is allowed to pass over it, I have to extract I guess the allowed tile and calculate the distance between the position player with the position goal, getting the real distance and then check cell per cell which has the lowest cost, but I do not know how to do that :c
func get_player_init_pos():
var pos = map_to_world(Vector2(54,1))pos.y += half_cell_size.y
return pos
func is_tile_vacant(pos, direction):
var curr_tile = world_to_map(pos)
var next_tile = get_cellv(curr_tile + direction)
var next_tile_pos = Vector2()
if(next_tile == 0):
next_tile_pos = map_to_world(curr_tile + direction)
else:next_tile_pos = pos
return next_tile_pos
I have this, the first part of the code is to locate the player in the map and the second is for check the tile walls in the map
You could roll your own path finding algorithm. However, there is little point in doing so, since Godot has a AStar class you can use. However, you probably don't need to use that either, because Godot has a navigation system. And that is what I'm going to suggest you to use.
First of all, you can specify both navigation and collision polygons on your tiles. You need to have the navigation polygons. Go ahead and do them.
Second you want to have a Navigation2D in the scene tree and have your TileMap as a child.
And third, you can ask the Navigation2D for a path with get_simple_path, you pass the start and end positions as arguments and you get an array of points that make up the path.
Since you mention A*, I'll briefly explain using the AStar too anyway.
First, you need to add the cells with add_point. It requires ids. It is a good idea to be clever with the ids so you can compute the id for a given position. For example x * width + y if you know the size.
So you can iterate over the tiles in your TileMap and call add_point for each one (You don't need to add cell that are not passable).
Then you need to specify the connections with connect_points (it takes the ids of the points as parameters).
And finally you can call get_point_path passing the start and end ids. Again it gives you a array of points.
I made a semicircular 2D shape in Godot. Now I'm trying to give it proper collisions. So far, I've found no way to do this. The CollisionShape2D node only allows simple shapes like circles and rectangles, and the CollisionPolygon2D shape won't allow me to make the curved shape I require. Is there any way I can get the proper collisions?
I am not familiar with a built-in function that does this.
However, you can do two things:
Approximate the circular shape with the CollisionPolygon2D. This is simple and will work. However, might not be very efficient.
You override the collision method for your object. It is also simple:
Say it is a semicircle in the direction head_dir. Simply:
dir := head_dir
position := this object position
circRadius := semi-circle radius
otherPos := other object position
inside = false
if(dotProduct(dir, otherPos) >= 0):
inside = true
if(inside):
if(norm(otherPos - position) > radius)
inside = false
return inside
The second method will give you the exact collision you look for. All you need is update head_dir.
What's the best method to check if a Vector2 is inside a Rectangle?
myRect.contains(myVector2) does not work, because it expects a Point or a Rectangle.
I know I could cast the the Vector2 to a Point or even to a Rectangle with a size of 1/1, but I am unsure about performance.
What are your experiences?
One of the overloaded versions of Contains for the Rectangle struct, takes an X and Y coordinate.
Rectangle rect = new Rectangle(-5, -5, 10, 10);
Vector2 myVector2 = Vector2.Zero;
rect.Contains((int)myVector2.X, (int)myVector2.Y)
I assume you're talking about myVector2 representing a point rather than a distance or direction.
While there may be additional execution time in casting vs creating a point like Point(myVector2.X, myVector2.Y), the implications are most likely too small for you to ever notice (generally should avoid premature optimization)
Go with whatever looks cleanest and easier to maintain. If it were me I'd probably just create the new point in the method call...
You could also write an extension method.
public static Point Origin(this Vector2 v)
{
//original proposal
//return new Point( (int)v.X, (int)v.Y );
//better! does correctly round the values
return new Point( Convert.ToInt32(v.X), convert.ToInt32(v.Y));
}
Then you could do something like this rect.Contains(vec.Origin)
Something to remember, though: this method will not actually check if the vector is contained in the rectangle, this will only check if the origin is. Remember, a vector is direction and magnitude.
So basically when I try to draw more a mesh inside an FBX file its orientation is always removed and it's scaled down. I'm not sure if the issue is caused by code or the way I'm exporting the FBX files. I have been trying to narrow down the cause and I am fairly sure it's not caused by the way I export the FBX (but I could be wrong), so it's either the XNA content pipeline or my drawing code
Here are some pics I took to show my problem, where the gray background is in 3Ds Max as I see it and red background is in XNA:
THis is as it appears in 3D StudioMax: http://i.stack.imgur.com/e0oW4.png
This is how it appears in XNA: http://i.stack.imgur.com/1vOcx.png
Both are being viewed from the same angle and direction but varying distances.
Now what is really odd is if I create another mesh in max, say a box, and export that (along with the original model), it works fine: http://i.stack.imgur.com/SIDg9.png
So long as there is more than one mesh in the fbx model it draws properly (though I'm still suspicious if it's drawing with proper scaling applied, i.e. if in Max it is 1 unit long in XNA it becomes something like 1.27 units long), if there is less its orientation which I applied to it in 3D studio max is removed when I draw it.
This is how I draw the model:
model.CopyAbsoluteBoneTransformsTo(boneTransforms);
foreach (ModelMesh mesh in model.Meshes)
{
foreach (BasicEffect effect in mesh.Effects)
{
effect.World = boneTransforms[mesh.ParentBone.Index];
Vector3 cameraPosition = Camera.Get.Position;// new Vector3(0, 0, 0);
//cameraPosition.X = -Camera.Get.PosX;
//cameraPosition.Y = Camera.Get.PosY;
effect.View = Camera.Get.View;// Matrix.CreateLookAt(cameraPosition, cameraPosition + Camera.Get.LookDir, Camera.Get.Up);
effect.Projection = Matrix.CreatePerspectiveFieldOfView(MathHelper.PiOver4,
BaseGame.Get.GraphicsDevice.Viewport.AspectRatio,
0.01f, 1000000); //Matrix.CreateOrthographic(800 / 1, 480 / 1, 0, 1000000);
//effect.TextureEnabled = true;
effect.LightingEnabled = true;
effect.PreferPerPixelLighting = true;
//effect.SpecularColor = new Vector3(1, 0, 0);
}
mesh.Draw();
}
Obviously mesh.draw() is called twice when there is more than one mesh in the fbx file..
Generally if you are having a problem with the position or scale of the mesh while rendering, then it's likely to be related to the matrices. Not necessarily the exporting, but rather how you use them in the code.
I use blender3d for modelling, but I know that Blender3d actually defines different spaces when you are creating the meshes within the editor. For example, if you create a mesh while in 'object' mode, the position/rotation/scale of the object in the scene will not be exported (because that object will be the root of a new tree, centered around 0,0,0). So I would check for a similar situation in 3DMax - make sure you are transforming the vertices in Max relative to 0,0,0, or else you may lose the 'initial' translation and when you render in XNA, all the objects will be rendered around your 0,0,0 (i.e. appear mixed together).
Failing that, and I can't remember exactly off the top of my head, but I think you may need to multiply the current mesh's absolute matrix transform with that of the parent's world matrix transform. Although it's been a while so I'm not too sure.
See also: Why is my image rotation algorithm not working?
This question isn't language specific, and is a math problem. I will however use some C++ code to explain what I need as I'm not experienced with the mathematic equations needed to express the problem (but if you know about this, I’d be interested to learn).
Here's how the image is composed:
ImageMatrix image;
image[0][0][0] = 1;
image[0][1][0] = 2;
image[0][2][0] = 1;
image[1][0][0] = 0;
image[1][1][0] = 0;
image[1][2][0] = 0;
image[2][0][0] = -1;
image[2][1][0] = -2;
image[2][2][0] = -1;
Here's the prototype for the function I'm trying to create:
ImageMatrix rotateImage(ImageMatrix image, double angle);
I'd like to rotate only the first two indices (rows and columns) but not the channel.
The usual way to solve this is by doing it backwards. Instead of calculating where each pixel in the input image ends up in the output image, you calculate where each pixel in the output image is located in the input image (by rotationg the same amount in the other direction. This way you can be sure that all pixels in the output image will have a value.
output = new Image(input.size())
for each pixel in input:
{
p2 = rotate(pixel, -angle);
value = interpolate(input, p2)
output(pixel) = value
}
There are different ways to do interpolation. For the formula of rotation I think you should check https://en.wikipedia.org/wiki/Rotation_matrix#In_two_dimensions
But just to be nice, here it is (rotation of point (x,y) angle degrees/radians):
newX = cos(angle)*x - sin(angle)*y
newY = sin(angle)*x + cos(angle)*y
To rotate an image, you create 3 points:
A----B
|
|
C
and rotate that around A. To get the new rotated image you do this:
rotate ABC around A in 2D, so this is a single euler rotation
traverse in the rotated state from A to B. For every pixel you traverse also from left to right over the horizontal line in the original image. So if the image is an image of width 100, height 50, you'll traverse from A to B in 100 steps and from A to C in 50 steps, drawing 50 lines of 100 pixels in the area formed by ABC in their rotated state.
This might sound complicated but it's not. Please see this C# code I wrote some time ago:
rotoZoomer by me
When drawing, I alter the source pointers a bit to get a rubber-like effect, but if you disable that, you'll see the code rotates the image without problems. Of course, on some angles you'll get an image which looks slightly distorted. The sourcecode contains comments what's going on so you should be able to grab the math/logic behind it easily.
If you like Java better, I also have made a java version once, 14 or so years ago ;) ->
http://www.xs4all.nl/~perseus/zoom/zoom.java
Note there's another solution apart from rotation matrices, that doesn't loose image information through aliasing.
You can separate 2D image rotation into skews and scalings, which preserve the image quality.
Here's a simpler explanation
It seems like the example you've provided is some edge detection kernel. So if what you want to is detect edges of different angles you'd better choose some continuous function (which in your case might be a parametrized gaussian of x1 multiplied by x2) and then rotate it according to formulae provided by kigurai. As a result you would be able to produce a diskrete kernel more efficiently and without aliasing.