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By rXpSwiss
Hello,
I am sending compressed json data from the UE4 client to a C++ server made with boost.
I am using ZLib to compress and decompress all json but it doesn't work. I am now encoding it in base64 to avoid some issues but that doesn't change a thing.
I currently stopped trying to send the data and I am writing it in a file from the client and trying to read the file and decompress on the server side.
When the server is trying to decompress it I get an error from ZLib : zlib error: iostream error
My question is the following : Did anyone manage to compress and decompress data between a UE4 client and a C++ server ?
I cannot really configure anything on the server side (because boost has its ZLib compressor) and I don't know what is wrong with the decompression.
Any idea ?
rXp

By Connor Rust
I am currently attempting to make a navigation mesh for our 2D top down game, which is a multiplayer game using Node.js as the server communication. At the moment, I have implemented A* over an obstacle hardnessmap, which is awfully slow and laggy at times when we test our game on Heroku. I have been trying to find an algorithm to automatically generate the navmesh after map creation, instead of me having to do this manually. I am currently attempting to use Delaunay's Triangulation Divide and Conquer algorithm, but I am running into some issues. I have already asked a question on StackOverflow and am not getting many suggestions and help from it, so I figured I would come here. Is there another algorithm that might be better to use for the navmesh generation in comparison to Deluanay's Triangulation? My current implementation seems extremely buggy during the merge step and I cannot find the error. I have checked over the code countless times, comparing it to the description of the algorithm from http://www.geom.uiuc.edu/~samuelp/del_project.html.
My current code is this:
class MapNode { constructor(x, y) { this.position = new Vector(x, y); this.neighbors = []; } distance(n) { return this.position.distance(n.position); } inNeighbor(n) { for (let i = 0; i < this.neighbors.length; i++) { if (this.neighbors[i] === n) return true; } return false; } addNeighbor(n) { this.neighbors = this.neighbors.filter((node) => node != n); this.neighbors.push(n); } addNeighbors(arr) { let self = this; arr.forEach((n) => self.neighbors.push(n)); } removeNeighbor(n) { this.neighbors = this.neighbors.filter((neighbor) => neighbor != n); } } class Triangle { constructor(p1, p2, p3) { this.p1 = p1; this.p2 = p2; this.p3 = p3; this.neighbors = []; } addNeighbors(n) { this.neighbors.push(n); } } function genSubMat(matrix, ignoreCol) { let r = []; for (let i = 0; i < matrix.length  1; i++) { r.push([]); for (let j = 0; j < matrix[0].length; j++) { if (j != ignoreCol) r[i].push(matrix[i + 1][j]); } } return r; } function determinantSqMat(matrix) { if (matrix.length != matrix[0].length) return false; if (matrix.length === 2) return matrix[0][0] * matrix[1][1]  matrix[1][0] * matrix[0][1]; let det = 0; for (let i = 0; i < matrix.length; i++) { let r = genSubMat(matrix, i); let tmp = matrix[0][i] * determinantSqMat(r); if (i % 2 == 0) det += tmp; else det = tmp; } return det; } // if d is in the circle formed by points a, b, and c, return > 0 // d is on circle, return 0 // d is outside of circle, return < 0 function inCircle(a, b, c, d) { let arr = [a, b, c, d]; let mat = [ [], [], [], [] ]; for (let i = 0; i < arr.length; i++) { mat[i][0] = 1; mat[i][1] = arr[i].position.x; mat[i][2] = arr[i].position.y; mat[i][3] = arr[i].position.x * arr[i].position.x + arr[i].position.y * arr[i].position.y; } return determinantSqMat(mat); } function walkable(from, to, hardnessMap) { let diff = new Vector(to.x  from.x, to.y  from.y); if (Math.abs(diff.x) > Math.abs(diff.y)) diff.scale(Math.abs(1 / diff.x)); else diff.scale(Math.abs(1 / diff.y)); let current = new Vector(from.x + diff.x, from.y + diff.y); while (Math.round(current.x) != to.x  Math.round(current.y) != to.y) { if (hardnessMap[Math.floor(current.y)][Math.floor(current.x)] === 1) return false; current.x += diff.x; current.y += diff.y; } return true; } function getLowest(nodes) { let lowest = nodes[0]; for (let i = 1; i < nodes.length; i++) { if (nodes[i].position.y < lowest.position.y) lowest = nodes[i]; } return lowest; } // returns the angle between 2 vectors, if cw is true, then return clockwise angle between, // else return the ccw angle between. b is the "hinge" point function angleBetween(a, b, c, cw) { let ba = new Vector(a.position.x  b.position.x, a.position.y  b.position.y); let bc = new Vector(c.position.x  b.position.x, c.position.y  b.position.y); let v0 = new Vector(0, 1); let angleBA = v0.angleBetween(ba) * 180 / Math.PI; if (angleBA < 0) angleBA += 360; let angleBC = v0.angleBetween(bc) * 180 / Math.PI; if (angleBC < 0) angleBC += 360; let smallest = Math.min(angleBA, angleBC); let largest = Math.max(angleBA, angleBC); let angle = largest  smallest; return (cw) ? angle : 360  angle; } function sortSmallestAngle(a, b, list, cw) { list.sort((m, n) => { let vab = new Vector(a.position.x  b.position.x, a.position.y  b.position.y); let vmb = new Vector(m.position.x  b.position.x, m.position.y  b.position.y); let vnb = new Vector(n.position.x  b.position.x, n.position.y  b.position.y); if (cw) return vab.angleBetween(vmb, cw)  vab.angleBetween(vnb, cw); else return vab.angleBetween(vnb, cw)  vab.angleBetween(vmb, cw); }); } // a is in list, b is in the other list function getPotential(a, b, list, cw) { sortSmallestAngle(b, a, list, cw); for (let i = 0; i < list.length  1; i++) { let angle = angleBetween(b, a, list[i], cw); if (angle > 180) return false; else if (inCircle(a, b, list[i], list[i + 1]) <= 0) return list[i]; else { a.removeNeighbor(list[i]); list[i].removeNeighbor(a); } } let potential = list[list.length  1]; if (potential) { let angle = angleBetween(a, b, potential, cw); if (angle > 180) return false; return potential; } return false; } function merge(leftNodes, rightNodes, leftBase, rightBase, hardnessMap) { leftBase.addNeighbor(rightBase); rightBase.addNeighbor(leftBase); let newLeft = leftNodes.filter((n) => n != leftBase); let newRight = rightNodes.filter((n) => n != rightBase); let potentialLeft = getPotential(leftBase, rightBase, newLeft, false); let potentialRight = getPotential(rightBase, leftBase, newRight, true); if (!potentialLeft && !potentialRight) return; else if (potentialLeft && !potentialRight) merge(newLeft, newRight, potentialLeft, rightBase, hardnessMap); else if (potentialRight && !potentialLeft) merge(newLeft, newRight, leftBase, potentialRight, hardnessMap); else { if (inCircle(leftBase, rightBase, potentialLeft, potentialRight) <= 0) merge(newLeft, newRight, potentialLeft, rightBase, hardnessMap); if (inCircle(leftBase, rightBase, potentialRight, potentialLeft) <= 0) merge(newLeft, newRight, leftBase, potentialRight, hardnessMap); } } // divide and conquer algorithm function delaunay(nodes, hardnessMap) { if (nodes.length <= 3) { for (let i = 0; i < nodes.length; i++) for (let j = 0; j < nodes.length; j++) if (i != j) nodes[i].addNeighbor(nodes[j]); return nodes; } else { nodes.sort((a, b) => { let tmp = a.position.x  b.position.x; if (tmp === 0) return b.position.y  a.position.y; return tmp; }); let l = nodes.length; let leftNodes; let rightNodes; if (l === 4) { leftNodes = delaunay(nodes.slice(0, 3), hardnessMap); rightNodes = delaunay(nodes.slice(3, 4), hardnessMap); } else { leftNodes = delaunay(nodes.slice(0, Math.floor(nodes.length / 2)), hardnessMap); rightNodes = delaunay(nodes.slice(Math.floor(nodes.length / 2), nodes.length), hardnessMap); } let leftBase = getLowest(leftNodes); let rightBase = getLowest(rightNodes); merge(leftNodes, rightNodes, leftBase, rightBase, hardnessMap); console.log("=============================MergeComplete================================"); return nodes; } }

By lucky6969b
I am not sure I can ask questions about a specific library here, but if you haven't already. I'd like to tag some polys in a navigation mesh that correspond to grass or road etc, I can give an extent to do so, or in another way, I can directly feed a geometry in and the polys are tagged this way. But I am looking into alternative ways such as allowing the user to tag the polys using a text file or bitmap file (like the way heightfields are done).. If I define a area map which is a grayscale image, and the values range from 0255, and for example, if the value of the first char is 0, then I can map this index to certain place in the navigation mesh, and say this is a walkable ground etc, unlike heightfields, where you define an image and the resultant thing is some terrain, but when you start off with a bitmap for area map, you end up with what? you see, I had the geometry already, the area map probably doesn't make sense here, same way as the text file thing....
Any ideas?
Jack

By sidbhati32
I am working on a game in which we control a rectangular box at the bottom of the screen. Three sphere which has alphabets in it fall down. When the game starts, a word is generated from the predefined list of words(which I'll give) and we are supposed to touch the correct sphere having the alphabet based on that word. The question is how to detect if I have touched the correct sphere.
secondly, if I have touched a correct sphere before and there is no recurrence of that alphabet in that word then during the second wave the game should not proceed if I touch the same alphabet again.
Looking forward to your answers, i have to submit this project in a couple of days. please help! (Working on Unity 3D)
Thanks

By Yarden2JR
Hi there everyone! I'm trying to implement SPH using CPU single core. I'm having troubles in making it stable. I'd like some help in order to understand what is wrong and how could I fix it. Please, take a look at the following videos:
Water inside sphere using Kelager's parameters
Water inside big box
Water inside thinner box
I've already tried using XSPH, the hash method to find the neighbors (now I'm using the regular grid, because the hash method didn't work for me) and two different ways of calculating the pressure force.
I'm using mostly the following articles:
ParticleBased Fluid Simulation for Interactive Applications, Matthias Müller, David Charypar and Markus Gross
Lagrangian Fluid Dynamics Using Smoothed Particle Hydrodynamics, Micky Kelager
Smoothed Particle Hydrodynamics RealTime Fluid Simulation Approach, David Staubach
Fluid Simulation using Smoothed Particle Hydrodynamics, Burak Ertekin
3D Langrangian Fluid Solver using SPH approximations, Chris Priscott
Any ideas? Thanks!



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