So I have tried to make a glass panel of car headlight by caping, extruding and so on. It didnt work, so I have created a spline from shape I need and somehow turned it into poly and now I am trying to weld vertices to the base. It doesnt work. Faces are flipped right way, object is attached back to base. Any idea? Thank you.
After you turn your spline to mesh you need to extrude the back face and delete it so you will be able to attach both objects together. Note that both object main faces should be deleted so you can weld vertices together. send a screenshot to see more details.
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I am working in aspnetcore using the most up to date GeoAPI and NetTopologySuite version for core. What I'm trying to do should be fairly simple but I can't seem to find the proper way to do it either through experimentation of googling. Or even what to call it, to be honest, which makes googling harder.
Hopefully someone can kick me in the right direction.
I have a multipolygon which may be made up of one or more polygons. I want to create a buffer around that multipolygon's points out to X distance. This is basically a map overlay with concentric areas of interest. A given point of interest may fall in the original multi polygon's shapes... or it might fall in the first or second buffer area. Kinda like an onion if the core of an onion had random shapes in it.
That first part is simple. Just iterate the multipolygon's points and apply a buffer to each point using the buffer method:
var bufferZonePoints = new List<IGeometry>();
foreach(var point in multiPolygon.Coordinates)
{
bufferZonePoints.Add(point.Buffer(x));
}
var bufferZone = this.geometryFactory.CreateMultiPolygon(bufferZonePoints);
That's fine. But it's giving me another multipolygon made up of thousands of points. When I use this as a map overlay, I get a hurricane of circles following the vague outlines of the original shape sort of looking like a spirograph drawing. All I want is basically the outer boundary of all the buffer circles without all the points in the center.
I tried doing a ConvexHull on the multipolygon and it looked correct at first until I realize that it was shaving off the angles on the outside in order to get the smallest polygon all those points fit into (which is what convex hulls do after all). But that causes problems in the stuff I'm overlaying. Some points of interest may be outside the actual buffer, but be inside if the convex hull decides to round off a bumpy area of the zone. (I hope that makes sense).
Basically what I'm trying to do is take that multipolygon made up of all those buffered points and squash it down into a single polygon made up all the outermost boundaries of the buffers. But without all the spirograph garbage in the middle. I don't really want a ConvexHull. I've also tried Union and the GeometryCombiner class, but none of these are doing what I want.
I don't know if this helps makes this mud any clearer but there is a setting in QGIS that when you plunk down two circles and the circles would overlap they combine into one big blob like soap bubbles and the boundaries in between vanish. That's kinda what I'm trying to do via code.
Does that make sense? Can anyone help?
After continuing to experiment with my mapping tool. It would appear that Union DOES actually give me the result I wanted.
I started with two polygons that were far enough apart to make it obvious what was going on, did a union on them and got back just the shell of the combination of them. As I added more of the buffered points to it, the shame became a bit more obvious.
That's pretty well what I wanted.
Thanks anyway though! Hopefully this will help someone else.
I'm currently rendering a 3D model (Wavefront .obj format) in my Qt program. Right now, I'm rendering the model using Scene3D in QML, and I'm able to get it to display in the viewing area. What I would like to do is have a user click on the model and generate a 2D cross section of the slice that I would like to plot on a different window. I'm quite new to 3D rendering, and a lot of Qt documentation isn't very descriptive. I've been reading Qt documentation, experimenting, and searching online with no luck. How can I create 2D slices of a 3D object Model in Qt 3D, preferably in QML? What Qt libraries or classes can I use to achieve this?
Unfortunately, the fact that models are stored as a set of surfaces makes this hard. QT probably doesn't have a built in method for this.
Consider, for example, that a model made of faces might be missing a face. What now? can you interpolate across that gap consistently from different angles? What about the fact that a cross-section probably won't contain any vertices?
But, of course, it can be solved. First, just don't allow un-closed surfaces (meshes with holes). Second, for finding the vertices of your cross-section, perform an intersection between every edge in your model and the plane you're using, and if there's an intersection, there's a point there. Third, to find the edges, look at the list of vertices, and any two that are from an edge on the same polygon in the mesh should be connected by an edge in the cross section. To find which direction the edge should go, project the normal of the polygon onto the plane your using. For filling, I don't really know what to do. I guess that's whatever you want it to be.
Currently I'm using "Douglas Peucker" algorithm.
My problem is that when I'm drawing,the previously drawn lines are also changing which of course not realistic. Is there other alternative algorithm to minimize the saved points but not altering the previous drawn points or other way to alter "Douglas Peucker" to fit my need?
Give your pencil drawing tool 2 optional methods for drawing:
Draw a new point on the path using mousemove (which is your current freeform method). This option will let the user add many points which will allow them to be very detailed in their drawing.
Draw a new point on the path only upon mousedown. This option simply connects the previous point on the path to the newly clicked point. This option will let the user add just a few very straight lines which will allow them to outline figures with long running straight edges.
If you are concerned about the freeform path changing while the user is drawing you can apply the simplifying algorithm just once after they have stopped moving the mouse for 1 second.
If you specify the Douglas-Peucker algorithm use a high bias for accuracy then the simplified path will remain quite true to the unsimplified path.
BTW, if you want to draw splines through your points then check out this nice previous post: how to draw smooth curve through N points using javascript HTML5 canvas?
Ok, here is the thing. Recently i decided i wanted to understand how Random map generation works. I found some papers and some arguments. The most interesting one was "Diamond Square algorithm" and "Midpoint Displacement". I still have to try to apply those to a software, but other than that, i ran into this site: http://www-cs-students.stanford.edu/~amitp/game-programming/polygon-map-generation/
As you can see, the idea is to use polygons. But i have no idea how to apply that a Tile-Based map, not even how to create those polygons using the tools i have (c++ and sdl). I am assuming there is no way to do it ( please correct me if i am wrong.) But if i am not, how does a non-tile map works, and how are these polygons generated?
This answer will not give you directly the answers you're looking for, but hopefully will get you close enough!
The Problem
I think what blocks you is how to represent the data. You're probably used to a 2D grid that simply represent the type of each tile. As you know, this is fine to handle a tile-based map, but doesn't properly allow you to model worlds where tiles are of a different shape.
Graphs
What I suggest to you, is to see the problem a bit differently. A grid is nothing more than a graph (more info) with nodes that have 4 (or 8 if you allow diagonals) implicit neighbor nodes. So first, what I would do if I was you, would be to move from your strict standard 2D grid to a more "loose" graph, where each node has a position, a position, a list of neighbors (in most cases you'll have corners with 2 neighbors, borders with 3 and "middle" tiles with 4) and finally a rendering component which simply draws your tile on screen at the given position. Once this is done, you should be able to have the exact same results on screen that you currently have with your "2D Tile-Based" engine by simply calling the rendering component with each node who's bounding box (didn't touch it in what you should add to your node, but I'll get back to this later) intersects with the camera's frustum (in a 2D world, it would most likely if the position +/- the size intersects the RECT currently being drawn).
Search
The more generic approach will also help you doing stuff like pathfinding with generic algorithms that explore nodes until they find a valid path (see A* or Dijkstra). Even if you decided to stick to a good old 2D Tile Map game, these techniques would still be useful!
Yeah but I want Polygons
I hear you! So, if you want polygons, basically all you need to do, is add to your nodes a list of vertices and the appropriate data that you might need to render your polygons (either vertex color, textures and U/V maps, etc...) and update your rendering component to do the appropriate OpenGL (this for example should help) calls to draw your nodes. Once again, the first step to iteratively upgrade your 2D Tile Engine to a polygon map engine would be to, for each tile in your map, give each of your nodes two triangles, a texture resource (the tile), and U/V mappings (0,0 - 0,1 - 1,0 and 1,1). Once again, when this step is done, you should have a "generic" polygon based tile map engine. The creation of most of this data can be created procedurally by calculating coordinates based on tile position, tile size, etc...
Convex Polygons
If you decide that you ever might need NPCs to navigate on your map or want to allow your player to navigate by clicking the map, I would suggest that you always use convex polygons (the triangle being the simplest for of a convex polygon). This allows your code that assume that two different positions on the same polygon can be navigated to in straight line.
Complex Maps
Based on the link you provided, you want to have rather complex maps. In this case, the author used Voronoi Diagrams to generate the polygons of the map. There are already solutions to do triangulation like that, but you might also want to use other techniques that are easier to work with if you're just switching to 3D like this one for example. Once you have interesting results, you should consider implementing serialization to save/open your map data from the game. If you want to create an editor, be aware that it might be a lot of work but can be worth it if you want people to help you creating maps or to add elements to the maps (like geometry that's not part of the terrain).
I went all over the place with this answer, but hopefully it helps!
Just iterate over all the tiles, and do a hit-test from the centre of the tile to the polys. Turn the type of the tile into the type of the polygon. Did you need more than that?
EDIT: Sorry, I realize that probably isn't helpful. Playing with procedural algorithms can be fun and profitable. Start with a loop that iterates over all tiles and chooses randomly whether or not the tile is occupied. Then, iterate over them again and choose whether it is occupied or its neighbour is.
Also, check out the source code for this: http://dustinfreeman.org/toys/wall7-dustin.html
If I have an object performing this CAKeyframe Animation path (it is just an oval shape in the upper region of an iphone..
UIBezierPath *trackPath = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(20, 100, 280, 150)];
Now imagine that at anytime during this paths travels I want to create a smooth path from its current position at a point in time and some point at the bottom of the screen.
By the way I am assuming that once I have a path I can stop the current CAKeyframeAnimation and add this path to a new CAKeyframe animation, but maybe if this is incorrect you can give me pointers here as well please.
So I said to myself "Self.....it looks like you are going to have to answer this one yourself as nobody even wants to edit it or say that it is a duplicate......"
So I was hoping for some easier or ready made way to do this. From what I have found there is no easy way. It seems the steps are going to be;
get the current position of the animated layer
calculate yourself with all your own code a nice smooth curve
add this path to an animation and animate it.
As for the calculation of a Bezier Curve I am still looking to find some class or code where points can be plugged into it and the two control points are produced for the UIBezier class to produce a curve.
In my case I am going to only animate "out" of my above questioned shape a determined points and thus have ready made smooth curves which I have prepared.
Animating a smooth exit from an oval at any point is very complicated and In my case just not worth it. So I have not done that.