Search Results

Search found 258 results on 11 pages for 'polygons'.

Page 1/11 | 1 2 3 4 5 6 7 8 9 10 11  | Next Page >

• Collisions between moving ball and polygons

  - by miguelSantirso

  I know this is a very typical problem and that there area a lot of similar questions, but I have been looking for a while and I have not found anything that fits what I want. I am developing a 2D game in which I need to perform collisions between a ball and simple polygons. The polygons are defined as an array of vertices. I have implemented the collisions with the bounding boxes of the polygons (that was easy) and I need to refine that collision in the cases where the ball collides with the bounding box. The ball can move quite fast and the polygons are not too big so I need to perform continuous collisions. I am looking for a method that allows me to detect if the ball collides with a polygon and, at the same time, calculate the new direction for the ball after bouncing in the polygon. (I am using XNA, in case that helps)

  Read the article

• Transform shape built of contour splines to simple polygons

  - by Cheery

  I've dumped glyphs from truetype file so I can play with them. They have shape contours that consist from quadratic bezier curves and lines. I want to output triangles for such shapes so I can visualize them for the user. Traditionally I might use libfreetype or scan-rasterise this kind of contours. But I want to produce extruded 3D meshes from the fonts and make other distortions with them. So, how to polygonise shapes consisting from quadratic bezier curves and lines? There's many contours that form the shape together. Some contours are additive and others are subtractive. The contours are never open. They form a loop. (Actually, I get only contour vertices from ttf glyphs, those vertices define whether they are part of the curve or not. Even though it is easy to decompose these into bezier curves and lines, knowing the data is represented this way may be helpful for polygonizing the contours to triangles)

  Read the article

• Cocos2dx- Draw primitives(polygons) on Update

  - by Haider

  In my game I'm trying to draw polygons on on each step i.e. update method. I call draw() method to draw new polygon with dynamic vertices. Following is my code: void HelloWorld::draw(){glLineWidth(1);CCPoint filledVertices[] = {ccp(drawX1,drawY1),ccp(drawX2,drawY2), ccp(drawX3,drawY3), ccp(drawX4,drawY4)};ccDrawSolidPoly( filledVertices, 4, ccc4f(0.5f, 0.5f, 1, 1 ));} I call the draw() method from the update(float dt) method. The engine is behaving inconsistently i.e. sometimes it displays the polygons and on other occasions it does not. Is it the right approach to do such a task? If not what is the best way to display large number of primitives?

  Read the article

• Rendering trillions of "atoms" instead of polygons?

  - by Baring

  I just saw a video about what the publishers call the "next major step after the invention of 3D". According to the person speaking in it, they use a huge amount of atoms grouped into clouds instead of polygons, to reach a level of unlimited detail. They tried their best to make the video understandable for persons with no knowledge of any rendering techniques, and therefore or for other purposes left out all details of how their engine works. The level of detail in their video does look quite impressive to me. How is it possible to render scenes using custom atoms instead of polygons on current hardware? (Speed, memory-wise) If this is real, why has nobody else even thought about it so far? I'm, as an OpenGL developer, really baffled by this and would really like to hear what experts have to say. Therefore I also don't want this to look like a cheap advert and will include the link to the video only if requested, in the comments section.

  Read the article

• 3DS Max 2012 OBJ file import missing polygons

  - by Vit

  I started learning OpenGL. I got to a point I want to import some "real" objects. After "Googling" I decided I will go with OBJ file for start, since it is simple to understand, and there are plenty of tutorials on how to read them properly. I have from university access to 3DS Max 2012. So I tried to create very simple model (just deformated cube) and exporting it using OBJ file, just to vertices and triangles for the moment, without textures, so I can examine its structure by myself. But if I imported it right back to 3DS from OBJ file, now it renders somewhat strange, like its smoothen, and with lightsource, even I have none in scene. But the geometry, its wireframe is intact. So I thought maybe it is problem of exporting only vertices and triangles so I downloaded Enterprise-D model from internet, exported with everything on (normals, textures everything), and again imported it. Now, some polygons are missing. So, I want to ask, am I doing something terribly wrong, or is there some incompatibility issue between .max and .obj file ? Even it is only simple textured model without any lightsources, animation etc.? Thanks. Edit: I tried objects with MeshLab, the first, deformated cube was absolutelly OK. But still bothers me that 3DS Max doesen´t render it properly. In Enterprise-D model, there are polygons missing even in MeshLab. I uploaded rar archive with .max model of Enterprise, same .obj model exported from 3DS, and obj model of deformated cube. Download here (2.5 MB, filesonic).

  Read the article

• Clipping polygons in XNA with stencil (not using spritebatch)

  - by Blau

  The problem... i'm drawing polygons, in this case boxes, and i want clip children polygons with its parent's client area. // Class Region public void Render(GraphicsDevice Device, Camera Camera) { int StencilLevel = 0; Device.Clear( ClearOptions.Stencil, Vector4.Zero, 0, StencilLevel ); Render( Device, Camera, StencilLevel ); } private void Render(GraphicsDevice Device, Camera Camera, int StencilLevel) { Device.SamplerStates[0] = this.SamplerState; Device.Textures[0] = this.Texture; Device.RasterizerState = RasterizerState.CullNone; Device.BlendState = BlendState.AlphaBlend; Device.DepthStencilState = DepthStencilState.Default; Effect.Prepare(this, Camera ); Device.DepthStencilState = GlobalContext.GraphicsStates.IncMask; Device.ReferenceStencil = StencilLevel; foreach ( EffectPass pass in Effect.Techniques[Technique].Passes ) { pass.Apply( ); Device.DrawUserIndexedPrimitives<VertexPositionColorTexture>( PrimitiveType.TriangleList, VertexData, 0, VertexData.Length, IndexData, 0, PrimitiveCount ); } foreach ( Region child in ChildrenRegions ) { child.Render( Device, Camera, StencilLevel + 1 ); } Effect.Prepare( this, Camera ); // This does not works Device.BlendState = GlobalContext.GraphicsStates.NoWriteColor; Device.DepthStencilState = GlobalContext.GraphicsStates.DecMask; Device.ReferenceStencil = StencilLevel; // This should be +1, but in that case the last drrawed is blue and overlap all foreach ( EffectPass pass in Effect.Techniques[Technique].Passes ) { pass.Apply( ); Device.DrawUserIndexedPrimitives<VertexPositionColorTexture>( PrimitiveType.TriangleList, VertexData, 0, VertexData.Length, IndexData, 0, PrimitiveCount ); } } public static class GraphicsStates { public static BlendState NoWriteColor = new BlendState( ) { ColorSourceBlend = Blend.One, AlphaSourceBlend = Blend.One, ColorDestinationBlend = Blend.InverseSourceAlpha, AlphaDestinationBlend = Blend.InverseSourceAlpha, ColorWriteChannels1 = ColorWriteChannels.None }; public static DepthStencilState IncMask = new DepthStencilState( ) { StencilEnable = true, StencilFunction = CompareFunction.Equal, StencilPass = StencilOperation.IncrementSaturation, }; public static DepthStencilState DecMask = new DepthStencilState( ) { StencilEnable = true, StencilFunction = CompareFunction.Equal, StencilPass = StencilOperation.DecrementSaturation, }; } How can achieve this? EDIT: I've just relized that the NoWriteColors.ColorWriteChannels1 should be NoWriteColors.ColorWriteChannels. :) Now it's clipping right. Any other approach?

  Read the article

• Using polygons instead of quads on Cocos2d

  - by rraallvv

  I've been looking under the hood of Cocos2d, and I think (please correct me if I'm wrong) that although working with quads is a key feature of the engine, it should't be dificult to make it work with arrays of vertices (aka polygons) instead of quads, being the quads a special case of an array of four vertices by the way, does anyone have any code that makes cocos2d render a texture filled polygon inside a batch node? the code posted here (http://www.cocos2d-iphone.org/forum/topic/8142/page/2#post-89393) does a nice job rendering a texture filled polygon but the class doesn't work with batch nodes

  Read the article

• Slick2D Rendering Lots of Polygons

  - by Hazzard

  I'm writing an little isometric game using Slick. The world terrain is made up of lots of quadrilaterals. In a small world that is 128 by 128 squares, over 16,000 quadrilaterals need to be rendered. This puts my pretty powerful computer down to 30 fps. I've though about caching "chunks" of the world so only single chunks would ever need updating at a time, but I don't know how to do this, and I am sure there are other ways to optimize it besides that. Maybe I'm doing the whole thing wrong, surely fancy 3D games that run fine on my machine are more intensive than this. My question is how can I improve the FPS and am I doing something wrong? Or does it actually take that much power to render those polygons? -- Here is the source code for the render method in my game state. It iterates through a 2d array or heights and draws polygons based on the height. public void render(GameContainer container, StateBasedGame game, Graphics gfx) throws SlickException { gfx.translate(offsetX * d + container.getWidth() / 2, offsetY * d + container.getHeight() / 2); gfx.scale(d, d); for (int y = 0; y < placeholder.length; y++) {// x & y are isometric // diag for (int x = 0; x < placeholder[0].length; x++) { Polygon poly; int hor = TestState.TILE_WIDTH * (x - y);// hor and ver are orthagonal int W = TestState.TILE_HEIGHT * (x + y) - 1 * heights[y + 1][x];//points to go off of int S = TestState.TILE_HEIGHT * (x + y) - 1 * heights[y + 1][x + 1]; int E = TestState.TILE_HEIGHT * (x + y) - 1 * heights[y][x + 1]; int N = TestState.TILE_HEIGHT * (x + y) - 1 * heights[y][x]; if (placeholder[y][x] == null) { poly = new Polygon();//Create actual surface polygon poly.addPoint(-TestState.TILE_WIDTH + hor, W); poly.addPoint(hor, S + TestState.TILE_HEIGHT); poly.addPoint(TestState.TILE_WIDTH + hor, E); poly.addPoint(hor, N - TestState.TILE_HEIGHT); float z = ((float) heights[y][x + 1] - heights[y + 1][x]) / 32 + 0.5f; placeholder[y][x] = new Tile(poly, new Color(z, z, z)); //ShapeRenderer.fill(placeholder[y][x]); } if (true) {//ONLY draw tile if it's on screen gfx.setColor(placeholder[y][x].getColor()); ShapeRenderer.fill(placeholder[y][x]); //gfx.fill(placeholder[y][x]); //placeholder[y][x]. //DRAW EDGES if (y + 1 == placeholder.length) {//draw South foundation edges gfx.setColor(Color.gray); Polygon found = new Polygon(); found.addPoint(-TestState.TILE_WIDTH + hor, W); found.addPoint(hor, S + TestState.TILE_HEIGHT); found.addPoint(hor, TestState.TILE_HEIGHT * (x + y + 1)); found.addPoint(-TestState.TILE_WIDTH + hor, TestState.TILE_HEIGHT * (x + y)); gfx.fill(found); } if (x + 1 == placeholder[0].length) {//north gfx.setColor(Color.darkGray); Polygon found = new Polygon(); found.addPoint(TestState.TILE_WIDTH + hor, E); found.addPoint(hor, S + TestState.TILE_HEIGHT); found.addPoint(hor, TestState.TILE_HEIGHT * (x + y + 1)); found.addPoint(TestState.TILE_WIDTH + hor, TestState.TILE_HEIGHT * (x + y)); gfx.fill(found); }//*/ } } } }

  Read the article

• Trying to detect collision between two polygons using Separating Axis Theorem

  - by Holly

  The only collision experience i've had was with simple rectangles, i wanted to find something that would allow me to define polygonal areas for collision and have been trying to make sense of SAT using these two links Though i'm a bit iffy with the math for the most part i feel like i understand the theory! Except my implementation somewhere down the line must be off as: (excuse the hideous font) As mentioned above i have defined a CollisionPolygon class where most of my theory is implemented and then have a helper class called Vect which was meant to be for Vectors but has also been used to contain a vertex given that both just have two float values. I've tried stepping through the function and inspecting the values to solve things but given so many axes and vectors and new math to work out as i go i'm struggling to find the erroneous calculation(s) and would really appreciate any help. Apologies if this is not suitable as a question! CollisionPolygon.java: package biz.hireholly.gameplay; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import biz.hireholly.gameplay.Types.Vect; public class CollisionPolygon { Paint paint; private Vect[] vertices; private Vect[] separationAxes; CollisionPolygon(Vect[] vertices){ this.vertices = vertices; //compute edges and separations axes separationAxes = new Vect[vertices.length]; for (int i = 0; i < vertices.length; i++) { // get the current vertex Vect p1 = vertices[i]; // get the next vertex Vect p2 = vertices[i + 1 == vertices.length ? 0 : i + 1]; // subtract the two to get the edge vector Vect edge = p1.subtract(p2); // get either perpendicular vector Vect normal = edge.perp(); // the perp method is just (x, y) => (-y, x) or (y, -x) separationAxes[i] = normal; } paint = new Paint(); paint.setColor(Color.RED); } public void draw(Canvas c, int xPos, int yPos){ for (int i = 0; i < vertices.length; i++) { Vect v1 = vertices[i]; Vect v2 = vertices[i + 1 == vertices.length ? 0 : i + 1]; c.drawLine( xPos + v1.x, yPos + v1.y, xPos + v2.x, yPos + v2.y, paint); } } /* consider changing to a static function */ public boolean intersects(CollisionPolygon p){ // loop over this polygons separation exes for (Vect axis : separationAxes) { // project both shapes onto the axis Vect p1 = this.minMaxProjection(axis); Vect p2 = p.minMaxProjection(axis); // do the projections overlap? if (!p1.overlap(p2)) { // then we can guarantee that the shapes do not overlap return false; } } // loop over the other polygons separation axes Vect[] sepAxesOther = p.getSeparationAxes(); for (Vect axis : sepAxesOther) { // project both shapes onto the axis Vect p1 = this.minMaxProjection(axis); Vect p2 = p.minMaxProjection(axis); // do the projections overlap? if (!p1.overlap(p2)) { // then we can guarantee that the shapes do not overlap return false; } } // if we get here then we know that every axis had overlap on it // so we can guarantee an intersection return true; } /* Note projections wont actually be acurate if the axes aren't normalised * but that's not necessary since we just need a boolean return from our * intersects not a Minimum Translation Vector. */ private Vect minMaxProjection(Vect axis) { float min = axis.dot(vertices[0]); float max = min; for (int i = 1; i < vertices.length; i++) { float p = axis.dot(vertices[i]); if (p < min) { min = p; } else if (p > max) { max = p; } } Vect minMaxProj = new Vect(min, max); return minMaxProj; } public Vect[] getSeparationAxes() { return separationAxes; } public Vect[] getVertices() { return vertices; } } Vect.java: package biz.hireholly.gameplay.Types; /* NOTE: Can also be used to hold vertices! Projections, coordinates ect */ public class Vect{ public float x; public float y; public Vect(float x, float y){ this.x = x; this.y = y; } public Vect perp() { return new Vect(-y, x); } public Vect subtract(Vect other) { return new Vect(x - other.x, y - other.y); } public boolean overlap(Vect other) { if( other.x <= y || other.y >= x){ return true; } return false; } /* used specifically for my SAT implementation which i'm figuring out as i go, * references for later.. * http://www.gamedev.net/page/resources/_/technical/game-programming/2d-rotated-rectangle-collision-r2604 * http://www.codezealot.org/archives/55 */ public float scalarDotProjection(Vect other) { //multiplier = dot product / length^2 float multiplier = dot(other) / (x*x + y*y); //to get the x/y of the projection vector multiply by x/y of axis float projX = multiplier * x; float projY = multiplier * y; //we want to return the dot product of the projection, it's meaningless but useful in our SAT case return dot(new Vect(projX,projY)); } public float dot(Vect other){ return (other.x*x + other.y*y); } }

  Read the article

• Would it be more efficient to handle 2D collision detection with polygons, rather than both squares/polygons?

  - by KleptoKat

  I'm working on a 2D game engine and I'm trying to get collision detection as efficient as possible. One thing I've noted is that I have a Rectangle Collision collider, a Shape (polygon) collider and a circle collider. Would it be more efficient (either dev-time wise or runtime wise) to have just one shape collider, rather than have that and everything else? I feel it would optimize my code in the back end, but how much would it affect my game at runtime? Should I be concerned with this at all, as 3D games generally have tens of thousands of polygons?

  Read the article

• Polygons vs sprites rendering performance in Unity for windows phone 8

  - by Géry Arduino

  I'm currently building a windows phone 8 game with unity, having 111 (no more no less) sprites being updated each frames. I have a strong overhead in the profiler (70% to 90% minimum) I tried the following to get higher frame rate, I'm running it with minimum quality settings, I tried disabling and enabling V-Sync Finally I managedto get 60Fps, but I still have large overhead. I believe I should have more than 60Fps for such few amount. Moreover, I still have to implement the game logic over this so I'd like some room in my FPS to be able to work. I was wondering if it would be better in terms of performance to use polygons instead of sprites? As sprites are quite new in Unity, (that would give me around 222 triangles). Did someone tried to check the performance differences between sprites and actual mesh renderes in Unity when it comes to phones? If so what could be the best option in that case? FYI : I'm using the Windows Phone 8 emulator on Visual studio, I have a compliant computer for that so it should normally reflect the behavior of a real phone (expecting some differences but still...) EDIT : To clarify my question i wonder what is the most efficient in windows phone 8 : Sprites or Mesh renderers?

  Read the article

• 2D SAT Collision Detection not working when using certain polygons

  - by sFuller

  My SAT algorithm falsely reports that collision is occurring when using certain polygons. I believe this happens when using a polygon that does not contain a right angle. Here is a simple diagram of what is going wrong: Here is the problematic code: std::vector<vec2> axesB = polygonB->GetAxes(); //loop over axes B for(int i = 0; i < axesB.size(); i++) { float minA,minB,maxA,maxB; polygonA->Project(axesB[i],&minA,&maxA); polygonB->Project(axesB[i],&minB,&maxB); float intervalDistance = polygonA->GetIntervalDistance(minA, maxA, minB, maxB); if(intervalDistance >= 0) return false; //Collision not occurring } This function retrieves axes from the polygon: std::vector<vec2> Polygon::GetAxes() { std::vector<vec2> axes; for(int i = 0; i < verts.size(); i++) { vec2 a = verts[i]; vec2 b = verts[(i+1)%verts.size()]; vec2 edge = b-a; axes.push_back(vec2(-edge.y,edge.x).GetNormailzed()); } return axes; } This function returns the normalized vector: vec2 vec2::GetNormailzed() { float mag = sqrt( x*x + y*y ); return *this/mag; } This function projects a polygon onto an axis: void Polygon::Project(vec2* axis, float* min, float* max) { float d = axis->DotProduct(&verts[0]); float _min = d; float _max = d; for(int i = 1; i < verts.size(); i++) { d = axis->DotProduct(&verts[i]); _min = std::min(_min,d); _max = std::max(_max,d); } *min = _min; *max = _max; } This function returns the dot product of the vector with another vector. float vec2::DotProduct(vec2* other) { return (x*other->x + y*other->y); } Could anyone give me a pointer in the right direction to what could be causing this bug?

  Read the article

• 2D SAT Collision Detection not working when using certain polygons (With example)

  - by sFuller

  My SAT algorithm falsely reports that collision is occurring when using certain polygons. I believe this happens when using a polygon that does not contain a right angle. Here is a simple diagram of what is going wrong: Here is the problematic code: std::vector<vec2> axesB = polygonB->GetAxes(); //loop over axes B for(int i = 0; i < axesB.size(); i++) { float minA,minB,maxA,maxB; polygonA->Project(axesB[i],&minA,&maxA); polygonB->Project(axesB[i],&minB,&maxB); float intervalDistance = polygonA->GetIntervalDistance(minA, maxA, minB, maxB); if(intervalDistance >= 0) return false; //Collision not occurring } This function retrieves axes from the polygon: std::vector<vec2> Polygon::GetAxes() { std::vector<vec2> axes; for(int i = 0; i < verts.size(); i++) { vec2 a = verts[i]; vec2 b = verts[(i+1)%verts.size()]; vec2 edge = b-a; axes.push_back(vec2(-edge.y,edge.x).GetNormailzed()); } return axes; } This function returns the normalized vector: vec2 vec2::GetNormailzed() { float mag = sqrt( x*x + y*y ); return *this/mag; } This function projects a polygon onto an axis: void Polygon::Project(vec2* axis, float* min, float* max) { float d = axis->DotProduct(&verts[0]); float _min = d; float _max = d; for(int i = 1; i < verts.size(); i++) { d = axis->DotProduct(&verts[i]); _min = std::min(_min,d); _max = std::max(_max,d); } *min = _min; *max = _max; } This function returns the dot product of the vector with another vector. float vec2::DotProduct(vec2* other) { return (x*other->x + y*other->y); } Could anyone give me a pointer in the right direction to what could be causing this bug? Edit: I forgot this function, which gives me the interval distance: float Polygon::GetIntervalDistance(float minA, float maxA, float minB, float maxB) { float intervalDistance; if (minA < minB) { intervalDistance = minB - maxA; } else { intervalDistance = minA - maxB; } return intervalDistance; //A positive value indicates this axis can be separated. } Edit 2: I have recreated the problem in HTML5/Javascript: Demo

  Read the article

• Construct A Polygon Out of Union of Many Polygons

  - by Ngu Soon Hui

  Supposed that I have many polygons, what is the best algorithm to construct a polygon--maybe with holes- out of the union of all those polygons? For my purpose, you can imagine each piece of a polygon as a jigsaw puzzle piece, when you complete them you will get a nice picture. But the catch is that a small portion <5% of the jigsaw is missing, and you are still require to form a picture as complete as possible; that's the polygon-- maybe with holes-- that I want to form. My naive approach is to take two polygons, union them, and take another polygon, union it with the union of the two polygons, and repeat this process until every single piece is union. Then I will run through the union polygon list and check whether there are still some polygons can be combined, and I will repeat this process until a satisfactory result is achieved. But this seems to be like an extremely naive approach. I just wonder is there any other better algorithm?

  Read the article

• Drawing and filling different polygons at the same time in MATLAB

  - by Hossein

  Hi,I have the code below. It load a CSV file into memory. This file contains the coordinates for different polygons.Each row of this file has X,Y coordinates and a string which tells that to which polygon this datapoint belongs. for example a polygone named "Poly1" with 100 data points has 100 rows in this file like : Poly1,X1,Y1 Poly1,X2,Y2 ... Poly1,X100,Y100 Poly2,X1,Y1 ..... The index.csv file has the number of datapoint(number of rows) for each polygon in file Polygons.csv. These details are not important. The thing is: I can successfully extract the datapoints for each polygon using the code below. However, When I plot the lines of different polygons are connected to each other and the plot looks crappy. I need the polygons to be separated(they are connected and overlapping the some areas though). I thought by using "fill" I can actually see them better. But "fill" just filles every polygon that it can find and that is not desirable. I only want to fill inside the polygons. Can someone help me? I can also send you my datapoint if necessary, they are less than 200Kb. Thanks [coordinates,routeNames,polygonData] = xlsread('Polygons.csv'); index = dlmread('Index.csv'); firstPointer = 0 lastPointer = index(1) for Counter=2:size(index) firstPointer = firstPointer + index(Counter) + 1 hold on plot(coordinates(firstPointer:lastPointer,2),coordinates(firstPointer:lastPointer,1),'r-') lastPointer = lastPointer + index(Counter) end

  Read the article

• Collision detection with multiple polygons simultaneously

  - by Craig Innes

  I've written a collision system which detects/resolves collisions between a rectangular player and a convex polygon world using the Separating Axis Theorem. This scheme works fine when the player is colliding with a single polygon, but when I try to create a level made up of combinations of these shapes, the player gets "stuck" between shapes when trying to move from one polygon to the other. The reason for this seems to be that collisions are detected after the player has been pushed through the shape by its movement or gravity. When the system resolves the collision, it resolves them in an order that doesn't make sense (for example, when the player is moving from one flat rectangle to another, gravity pushes them below the ground, but the collision with the left hand side of the second block is resolved before the collision with the top of the block, meaning the player is pushed back left before being pushed back up). Other similar posts have resolved this problem by having a strict rule on which axes to resolve first. For example, always resolve the collision on the y axis, then if the object is still colliding with things, resolve on the x axis. This solution only works in the case of a completely axis oriented box world, and doesn't solve the problem if the player is stuck moving along a series of angled shapes or sliding down a wall. Does any one have any ideas of how I could alter my collision system to prevent these situations from happening?

  Read the article

• OpenGL ES 2.0: Filtering Polygons within VBO

  - by Bunkai.Satori

  Say, I send 10 polygon pairs (one polygon pair == one 2d sprite == one rectangle == two triangles) into OpenGL ES 2.0 VBO. The 10 polygon pairs represent one animated 2D object consisting of 10 frames. The 10 frames, of course, can not be rendered all at the same time, but will be rendered in particular order to make up smooth animation. Would you have an advice, how to pick up proper polygon pair for rendering (4 vertices) inside Vertex Shader from the VBO? Creating separate VBO for each frame would end up with thousands of VBOs, which is not the right way of doing it. I use OpenGL ES 2.0, and VBOs for both Vertices and Indices.

  Read the article

• Splitting Graph into distinct polygons in O(E) complexity

  - by Arthur Wulf White

  If you have seen my last question: trapped inside a Graph : Find paths along edges that do not cross any edges How do you split an entire graph into distinct shapes 'trapped' inside the graph(like the ones described in my last question) with good complexity? What I am doing now is iterating over all edges and then starting to traverse while always taking the rightmost turn. This does split the graph into distinct shapes. Then I eliminate all the excess shapes (that are repeats of previous shapes) and return the result. The complexity of this algorithm is O(E^2). I am wondering if I could do it in O(E) by removing edges I already traversed previously. My current implementation of that returns unexpected results.

  Read the article

• Scanline filling of polygons that share edges and vertices

  - by Belgin

  In this picture (a perspective projection of an icosahedron), the scanline (red) intersects that vertex at the top. In an icosahedron each edge belongs to two triangles. From edge a, only one triangle is visible, the other one is in the back. Same for edge d. Also, in order to determine what color the current pixel should be, each polygon has a flag which can either be 'in' or 'out', depending upon where on the scanline we currently are. Flags are flipped according to the intersection of the scanline with the edges. Now, as we go from a to d (because all edges are intersected with the scanline at that vertex), this happens: the triangle behind triangle 1 and triangle 1 itself are set 'in', then 2 is set in and 1 is 'out', then 3 is set 'in', 2 is 'out' and finally 3 is 'out' and the one behind it is set 'in', which is not the desired behavior because we only need the triangles which are facing us to be set 'in', the rest should be 'out'. How do process the edges in the Active Edge List (a list of edges that are currently intersected by the scanline) so the right polys are set 'in'? Also, I should mention that the edges are unique, which means there exists an array of edges in the data structure of the icosahedron which are pointed to by edge pointers in each of the triangles.

  Read the article

• Open GL polygons not displaying

  - by Darestium

  I have tried to follow nehe's opengl tutorial lesson 2. I use sfml for my window creation. The problem I have is that both the triangle and the quad don't show up on the screen: #include <SFML/System.hpp> #include <SFML/Window.hpp> #include <iostream> void processEvents(sf::Window *app); void processInput(sf::Window *app, const sf::Input &input); void renderCube(sf::Window *app, sf::Clock *clock); void renderGlScene(sf::Window *app); void init(); int main() { sf::Window app(sf::VideoMode(800, 600, 32), "Nehe Lesson 2"); app.UseVerticalSync(false); init(); while (app.IsOpened()) { processEvents(&app); renderGlScene(&app); app.Display(); } return EXIT_SUCCESS; } void init() { glClearDepth(1.f); glClearColor(0.f, 0.f, 0.f, 0.f); // Enable z-buffer and read and write glEnable(GL_DEPTH_TEST); glDepthMask(GL_TRUE); // Setup a perpective projection glMatrixMode(GL_MODELVIEW); glLoadIdentity(); gluPerspective(45.f, 1.f, 1.f, 500.f); glShadeModel(GL_SMOOTH); } void processEvents(sf::Window *app) { sf::Event event; while (app->GetEvent(event)) { if (event.Type == sf::Event::Closed) { app->Close(); } if (event.Type == sf::Event::KeyPressed && event.Key.Code == sf::Key::Escape) { app->Close(); } } } void renderGlScene(sf::Window *app) { app->SetActive(); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear the screen and the depth buffer glLoadIdentity(); // Reset the view glTranslatef(-1.5f, 0.0f, -6.0f); // Move Left 1.5 units and into the screen 6.0 glBegin(GL_TRIANGLES); glVertex3f( 0.0f, 1.0f, 0.0f); // Top glVertex3f(-1.0,-1.0f, 0.0f); // Bottom Left glVertex3f( 1.0f,-1.0f, 0.0f); // Bottom Right glEnd(); glTranslatef(3.0f, 0.0f, 0.0f); glBegin(GL_QUADS); // Draw a quad glVertex3f(-1.0f, 1.0f, 0.0f); glVertex3f( 1.0f, 1.0f, 0.0f); glVertex3f( 1.0f,-1.0f, 0.0f); glVertex3f(-1.0f,-1.0f, 0.0f); glEnd(); } I would greatly appreciate it if someone could help me resolve my issue.

  Read the article

• Selecting a good SQL Server 2008 spatial index with large polygons

  - by andynormancx

  I'm having some fun trying to pick a decent SQL Server 2008 spatial index setup for a data set I am dealing with. The dataset is polygons, representing contours over the whole globe. There are 106,000 rows in the table, the polygons are stored in a geometry field. The issue I have is that many of the polygons cover a large portion of the globe. This seems to make it very hard to get a spatial index that will eliminate many rows in the primary filter. For example, look at the following query: SELECT "ID","CODE","geom".STAsBinary() as "geom" FROM "dbo"."ContA" WHERE "geom".Filter( geometry::STGeomFromText('POLYGON ((-142.03193662573682 59.53396984952896, -142.03193662573682 59.88928136451884, -141.32743833481925 59.88928136451884, -141.32743833481925 59.53396984952896, -142.03193662573682 59.53396984952896))', 4326) ) = 1 This is querying an area which intersects with only two of the polygons in the table. No matter what combination of spatial index settings I chose, that Filter() always returns around 60,000 rows. Replacing Filter() with STIntersects() of course returns just the two polygons I want, but of course takes much longer (Filter() is 6 seconds, STIntersects() is 12 seconds). Can anyone give me any hints on whether there is a spatial index setup that is likely to improve on 60,000 rows or is my dataset just not a good match for SQL Server's spatial indexing ?

  Read the article

• Creating many polygons with OpenGL is slow?

  - by user146780

  I want to draw many polygons to the screen but i'm quickly noticing that it slows down quickly. As a test I did this: for(int i = 0; i < 50; ++i) { glBegin( GL_POLYGON); glColor3f( 0.0f, 1, 0.0f ); glVertex2f( 500.0 + frameGL.GetCameraX(), 0.0f + frameGL.GetCameraY()); glColor3f( 0.0f, 1.0f, 0.0f ); glVertex2f( 900.0 + frameGL.GetCameraX(), 0.0f + frameGL.GetCameraY()); glColor3f( 0.0f, 0.0f, 0.5 ); glVertex2f(900.0 + frameGL.GetCameraX(), 500.0f + frameGL.GetCameraY() + (150)); glColor3f( 0.0f, 1.0f, 0.0f ); glVertex2f( 500 + frameGL.GetCameraX(), 500.0f + frameGL.GetCameraY()); glColor3f( 1.0f, 1.0f, 0.0f ); glVertex2f( 300 + frameGL.GetCameraX(), 200.0f + frameGL.GetCameraY()); glEnd(); } This is only 50 polygons and already it's gtting slow. I can't upload them directly to the card because my program will allow the user to reshape the verticies. My question is, how can I speed this up. I'm not using depth. I also know it's not my GetCamera() functions because if I create 500,000 polygons spread apart t's fine, it just has trouble showing them in the view. If a graphics card can support 500,000,000 on screen polygons per second, this should be easy right? Thanks

  Read the article

• Intersection of Inner Polygons of MKPolygon being colored - iOS

  - by Josh Glick

  I am trying to create a fog of war style map where areas I have visited are uncovered and the rest of the map is "hidden". I am using a MKPolygonOverlay that covers the whole map and create inner polygons around all the locations I have visited. However in areas where these inner polygons overlap, that portion of the overlay is still being drawn. As a new user I can't post pictures but here is a link to the image: http://dl.dropbox.com/u/13815916/Screen%20Shot%202012-06-29%20at%204.40.20%20AM.png

  Read the article

• android opengl es texture mapping into polygons

  - by kamil

  I wrote opengl es code for android to map textures on a square but i want to draw texture on polygons. When user moved the image, texture will be mapped on polygons have more vertexes. I tried the arrays combination below for pentagon but i could not find the correct triangle combination in indices array. public float vertices[] = { // -1.0f, 1.0f, 0.0f, //Top Left // -1.0f, -1.0f, 0.0f, //Bottom Left // 1.0f, -1.0f, 0.0f, //Bottom Right // 1.0f, 1.0f, 0.0f //Top Right -1.0f, 1.0f, 0.0f, //Top Left -1.0f, -1.0f, 0.0f, //Bottom Left 1.0f, -1.0f, 0.0f, //Bottom Right 1.0f, 1.0f, 0.0f, //Top Right 0.4f, 1.4f, 0.0f }; /** Our texture pointer */ private int[] textures = new int[1]; /** The initial texture coordinates (u, v) */ private float texture[] = { //Mapping coordinates for the vertices // 1.0f, 0.0f, // 1.0f, 1.0f, // 0.0f, 1.0f, // 0.0f, 0.0f, // 0.0f, 1.0f, // 0.0f, 0.0f, // 1.0f, 0.0f, // 1.0f, 1.0f, 0.0f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f, 0.7f, }; /** The initial indices definition */ private byte indices[] = { //2 triangles // 0,1,2, 2,3,0, 0,1,2, 2,3,4, 3,4,0, //triangles for five vertexes }; i draw with the code below gl.glDrawElements(GL10.GL_TRIANGLES, indices.length, GL10.GL_UNSIGNED_BYTE, indexBuffer);

  Read the article

• Combine Arbitrary number of polygons together

  - by Jakobud

  I have an arbitrary number of polygons (hexes in this case) that are arranged randomly, but they are all touching another hex. Each individual hex has 6 x,y vertices. The vertex's are known for all the hexes. Can anyone point me in the direction of an algorithm that will combine all the hexes into a single polygon? Essentially I'm just looking for a function that spits out an array of vertex locations that are ordered in a way that when drawing lines from one to the next, it forms the polygon. This is my method so far: Create array of all the vertices for all the hexes. Determine the number of times a vertex occurs in the array If vertex is in the array 3+ times, delete the vertices from the array. If vertex is in the array 2 times, delete one of them. The next step is tricky though. I'm using canvas to draw out these polygons, which essentially involves drawing a line from one vertex to the next. So the order of the vertices in the final array is important. It can't be sorted arbitrarily. Also, I'm not looking for a "convex hull" algorithm, as that would not draw the polygon correctly. Are there any functions out there that do something like this? Am I on the right track or is there a better more efficient way?

  Read the article

1 2 3 4 5 6 7 8 9 10 11  | Next Page >