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  • Software rendering 3d triangles in the proper order

    - by at.
    I'm implementing a basic 3d rendering engine in software (for education purposes, please don't mention to use an API). When I project a triangle from 3d to 2d coordinates, I draw the triangle. However, it's in a random order and so whatever gets drawn last draws on top of all other triangles (which might be in front of triangles it shouldn't be in front of)... Intuitively, seems I need to draw the triangles in the correct order. So I can calculate all their distances to the camera and sort by that. The objects furthest away get drawn last. Is this the proper way to render triangles? If I'm sorting all the objects, this is n*log(n) now. Is this the most efficient way to do this?

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  • Why do game engines convert models to triangles compared to keeping it as four side polygon

    - by Grant
    I've worked using maya for animation and more film orientated projects however I am also focusing on my studies on video game development (eventually want to be either programmer or some sort of TD with programming and 3D skills). Anyways, I was talking with one of my professor and we couldn't figure out why all game engines (that I know of) convert to triangles. Anyone happen to know why game engines convert to triangles compared to leaving the models as four sided polygons? Also what are the pros and cons (if any) of doing this? Thanks in advance.

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  • Drawing texture does not work anymore with a small amount of triangles

    - by Paul
    When i draw lines, the vertices are well connected. But when i draw the texture inside the triangles, it only works with i<4 in the for loop, otherwise with i<5 for example, there is a EXC_BAD_ACCESS message, at @synthesize textureImage = _textureImage. I don't understand why. (The generatePolygons method seems to work fine as i tried to draw lines with many vertices as in the second image below. And textureImage remains the same for i<4 or i<5 : it's a 512px square image). Here are the images : What i want to achieve is to put the red points and connect them to the y-axis (the green points) and color the area (the green triangles) : If i only draw lines, it works fine : Then with a texture color, it works for i<4 in the loop (the red points in my first image, plus the fifth one to connect the last y) : But then, if i set i<5, the debug tool says EXC_BAD_ACCESS at the synthesize of _textureImage. Here is my code : I set a texture color in HelloWordLayer.mm with : CCSprite *textureImage = [self spriteWithColor:color3 textureSize:512]; _terrain.textureImage = textureImage; Then in the class Terrain, i create the vertices and put the texture in the draw method : @implementation Terrain @synthesize textureImage = _textureImage; //EXC_BAD_ACCESS for i<5 - (void)generatePath2{ CGSize winSize = [CCDirector sharedDirector].winSize; float x = 40; float y = 0; for(int i = 0; i < kMaxKeyPoints+1; ++i) { _hillKeyPoints[i] = CGPointMake(x, y); x = 150 + (random() % (int) 30); y += 30; } } -(void)generatePolygons{ _nPolyVertices = 0; float x1 = 0; float y1 = 0; int keyPoints = 0; for (int i=0; i<4; i++){ /* HERE : 4 = OK / 5 = crash */ //V0: at (0,0) _polyVertices[_nPolyVertices] = CGPointMake(x1, y1); _polyTexCoords[_nPolyVertices++] = CGPointMake(x1, y1); //V1: to the first "point" _polyVertices[_nPolyVertices] = CGPointMake(_hillKeyPoints[keyPoints].x, _hillKeyPoints[keyPoints].y); _polyTexCoords[_nPolyVertices++] = CGPointMake(_hillKeyPoints[keyPoints].x, _hillKeyPoints[keyPoints].y); keyPoints++; //from point at index 0 to 1 //V2, same y as point n°2: _polyVertices[_nPolyVertices] = CGPointMake(0, _hillKeyPoints[keyPoints].y); _polyTexCoords[_nPolyVertices++] = CGPointMake(0, _hillKeyPoints[keyPoints].y); //V1 again _polyVertices[_nPolyVertices] = _polyVertices[_nPolyVertices-2]; _polyTexCoords[_nPolyVertices++] = _polyVertices[_nPolyVertices-2]; //V2 again _polyVertices[_nPolyVertices] = _polyVertices[_nPolyVertices-2]; _polyTexCoords[_nPolyVertices++] = _polyVertices[_nPolyVertices-2]; //V3 = same x,y as point at index 1 _polyVertices[_nPolyVertices] = CGPointMake(_hillKeyPoints[keyPoints].x, _hillKeyPoints[keyPoints].y); _polyTexCoords[_nPolyVertices] = CGPointMake(_hillKeyPoints[keyPoints].x, _hillKeyPoints[keyPoints].y); y1 = _polyVertices[_nPolyVertices].y; _nPolyVertices++; } } - (id)init { if ((self = [super init])) { [self generatePath2]; [self generatePolygons]; } return self; } - (void) draw { //glDisable(GL_TEXTURE_2D); glDisableClientState(GL_COLOR_ARRAY); glDisableClientState(GL_TEXTURE_COORD_ARRAY); glBindTexture(GL_TEXTURE_2D, _textureImage.texture.name); glColor4f(1, 1, 1, 1); glVertexPointer(2, GL_FLOAT, 0, _polyVertices); glTexCoordPointer(2, GL_FLOAT, 0, _polyTexCoords); glDrawArrays(GL_TRIANGLE_STRIP, 0, (GLsizei)_nPolyVertices); glColor4f(1, 1, 1, 1); for(int i = 1; i < 40; ++i) { ccDrawLine(_polyVertices[i-1], _polyVertices[i]); } // restore default GL states glEnable(GL_TEXTURE_2D); glEnableClientState(GL_COLOR_ARRAY); glEnableClientState(GL_TEXTURE_COORD_ARRAY); } Do you see anything wrong in this code? Thanks for your help

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  • Texturize a shape of multiple triangles in 2D

    - by Deukalion
    This is an example of a shape consisting of multiple points, triangles and eventually a shape: Red Dots = Vector3 (X, Y, Z) or Vector2 (X, Y) If I have a Texture of a certain size, how do I texturize this area in the best way so that the texture inside the shape matches the shape and does not overlap anywhere? Perhaps also with a chance to scale the texture in case it's too small or to big for the shape, but still so that it gets rendered correctly. Do I treat the shape as a rectangle? Figure out it's 4 corners? Or do I calculate the distance between Center - (Texture Width / 2) and Point (to see how "many" times the texture can fit between on that axis to estimate at what Coordinates the Texture should be at that certain point? I've looked at Texture Mapping but haven't found any concrete examples that it explains it well, it's also confusing with 0.0-1.0 values for Texture Coordinates.

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  • Drawing multiple triangles at once isn't working

    - by Deukalion
    I'm trying to draw multiple triangles at once to make up a "shape". I have a class that has an array of VertexPositionColor, an array of Indexes (rendered by this Triangulation class): http://www.xnawiki.com/index.php/Polygon_Triangulation So, my "shape" has multiple points of VertexPositionColor but I can't render each triangle in the shape to "fill" the shape. It only draws the first triangle. struct ShapeColor { // Properties (not all properties) VertexPositionColor[] Points; int[] Indexes; } First method that I've tried, this should work since I iterate through the index array that always are of "3s", so they always contain at least one triangle. //render = ShapeColor for (int i = 0; i < render.Indexes.Length; i += 3) { device.DrawUserIndexedPrimitives<VertexPositionColor> ( PrimitiveType.TriangleList, new VertexPositionColor[] { render.Points[render.Indexes[i]], render.Points[render.Indexes[i+1]], render.Points[render.Indexes[i+2]] }, 0, 3, new int[] { 0, 1, 2 }, 0, 1 ); } or the method that should work: device.DrawUserIndexedPrimitives<VertexPositionColor> ( PrimitiveType.TriangleList, render.Points, 0, render.Points.Length, render.Indexes, 0, render.Indexes.Length / 3, VertexPositionColor.VertexDeclaration ); No matter what method I use this is the "typical" result from my Editor (in Windows Forms with XNA) It should show a filled shape, because the indexes are right (I've checked a dozen of times) I simply click the screen (gets the world coordinates, adds a point from a color, when there are 3 points or more it should start filling out the shape, it only draws the lines (different method) and only 1 triangle). The Grid isn't rendered with "this" shape. Any ideas?

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  • Adding Vertices to a dynamic mesh via Method Call

    - by Raven Dreamer
    I have a C# Struct with a static method, "Get Shape" which populates a List with the vertices of a polyhedron. Method Signature: public static void GetShape(Block b, int x, int y, int z, List<Vector3> vertices, List<int> triangles, List<Vector2> uvs, List<Vector2> uv2s) Adding directly to the vertices list (via vertices.Add(vector3) ), the code works as expected, and the new polyhedron appears when I trigger the method. However, I want to do some processing on the vertices I'm adding (a rotation), and the most sensible way I can think to do that is by creating a separate list of Vector3s, and then combining the lists when I'm done. However, vertices.AddRange(newVerts) does not add the shape to the mesh, nor does a foreach loop with verts.Add(vertices[i]). And this is before I've added in any of the processing! I have a feeling this might stem from passing the list of vertices in as a parameter, rather than returning a list and then adding to the vertices in the calling object, but since I'm filling 4 lists, I was trying to avoid having to create a data struct to return all four at once. Any ideas? The working version of the method is reprinted below, in full: public static void GetShape(Block b, int x, int y, int z, List<Vector3> vertices, List<int> triangles, List<Vector2> uvs, List<Vector2> uv2s) { //List<Vector3> vertices = new List<Vector3>(); int l_blockShape = b.blockShape; int l_blockType = b.blockType; //CheckFace checks if the block is empty //if this block is empty, don't draw anything. int vertexIndex; //only y faces need to be hidden. //if((l_blockShape & BlockShape.NegZFace) == BlockShape.NegZFace) { vertexIndex = vertices.Count; //top left, top right, bottom right, bottom left vertices.Add(new Vector3(x+.2f, y + 1, z+.2f)); vertices.Add(new Vector3(x+.8f, y + 1, z+.2f)); vertices.Add(new Vector3(x+.8f, y , z+.2f)); vertices.Add(new Vector3(x+.2f, y , z+.2f)); // first triangle for the face triangles.Add(vertexIndex); triangles.Add(vertexIndex+1); triangles.Add(vertexIndex+3); // second triangle for the face triangles.Add(vertexIndex+1); triangles.Add(vertexIndex+2); triangles.Add(vertexIndex+3); //UVs for the face uvs.Add( new Vector2(0,1)); uvs.Add( new Vector2(1,1)); uvs.Add( new Vector2(1,0)); uvs.Add( new Vector2(0,0)); //UV2s (lightmapping?) uv2s.Add( new Vector2(0,1)); uv2s.Add( new Vector2(1,1)); uv2s.Add( new Vector2(1,0)); uv2s.Add( new Vector2(0,0)); } //XY Z+1 face //if((l_blockShape & BlockShape.PosZFace) == BlockShape.PosZFace) { vertexIndex = vertices.Count; //top left, top right, bottom right, bottom left vertices.Add(new Vector3(x+.8f, y + 1, z+.8f)); vertices.Add(new Vector3(x+.2f, y + 1, z+.8f)); vertices.Add(new Vector3(x+.2f, y , z+.8f)); vertices.Add(new Vector3(x+.8f, y , z+.8f)); // first triangle for the face triangles.Add(vertexIndex); triangles.Add(vertexIndex+1); triangles.Add(vertexIndex+3); // second triangle for the face triangles.Add(vertexIndex+1); triangles.Add(vertexIndex+2); triangles.Add(vertexIndex+3); //UVs for the face uvs.Add( new Vector2(0,1)); uvs.Add( new Vector2(1,1)); uvs.Add( new Vector2(1,0)); uvs.Add( new Vector2(0,0)); //UV2s (lightmapping?) uv2s.Add( new Vector2(0,1)); uv2s.Add( new Vector2(1,1)); uv2s.Add( new Vector2(1,0)); uv2s.Add( new Vector2(0,0)); } //ZY face //if((l_blockShape & BlockShape.NegXFace) == BlockShape.NegXFace) { vertexIndex = vertices.Count; //top left, top right, bottom right, bottom left vertices.Add(new Vector3(x+.2f, y + 1, z+.8f)); vertices.Add(new Vector3(x+.2f, y + 1, z+.2f)); vertices.Add(new Vector3(x+.2f, y , z+.2f)); vertices.Add(new Vector3(x+.2f, y , z+.8f)); // first triangle for the face triangles.Add(vertexIndex); triangles.Add(vertexIndex+1); triangles.Add(vertexIndex+3); // second triangle for the face triangles.Add(vertexIndex+1); triangles.Add(vertexIndex+2); triangles.Add(vertexIndex+3); //UVs for the face uvs.Add( new Vector2(0,1)); uvs.Add( new Vector2(1,1)); uvs.Add( new Vector2(1,0)); uvs.Add( new Vector2(0,0)); //UV2s (lightmapping?) uv2s.Add( new Vector2(0,1)); uv2s.Add( new Vector2(1,1)); uv2s.Add( new Vector2(1,0)); uv2s.Add( new Vector2(0,0)); } //ZY X+1 face // if((l_blockShape & BlockShape.PosXFace) == BlockShape.PosXFace) { vertexIndex = vertices.Count; //top left, top right, bottom right, bottom left vertices.Add(new Vector3(x+.8f, y + 1, z+.2f)); vertices.Add(new Vector3(x+.8f, y + 1, z+.8f)); vertices.Add(new Vector3(x+.8f, y , z+.8f)); vertices.Add(new Vector3(x+.8f, y , z+.2f)); // first triangle for the face triangles.Add(vertexIndex); triangles.Add(vertexIndex+1); triangles.Add(vertexIndex+3); // second triangle for the face triangles.Add(vertexIndex+1); triangles.Add(vertexIndex+2); triangles.Add(vertexIndex+3); //UVs for the face uvs.Add( new Vector2(0,1)); uvs.Add( new Vector2(1,1)); uvs.Add( new Vector2(1,0)); uvs.Add( new Vector2(0,0)); //UV2s (lightmapping?) uv2s.Add( new Vector2(0,1)); uv2s.Add( new Vector2(1,1)); uv2s.Add( new Vector2(1,0)); uv2s.Add( new Vector2(0,0)); } //ZX face if((l_blockShape & BlockShape.NegYFace) == BlockShape.NegYFace) { vertexIndex = vertices.Count; //top left, top right, bottom right, bottom left vertices.Add(new Vector3(x+.8f, y , z+.8f)); vertices.Add(new Vector3(x+.8f, y , z+.2f)); vertices.Add(new Vector3(x+.2f, y , z+.2f)); vertices.Add(new Vector3(x+.2f, y , z+.8f)); // first triangle for the face triangles.Add(vertexIndex+3); triangles.Add(vertexIndex+1); triangles.Add(vertexIndex); // second triangle for the face triangles.Add(vertexIndex+3); triangles.Add(vertexIndex+2); triangles.Add(vertexIndex+1); //UVs for the face uvs.Add( new Vector2(0,1)); uvs.Add( new Vector2(1,1)); uvs.Add( new Vector2(1,0)); uvs.Add( new Vector2(0,0)); //UV2s (lightmapping?) uv2s.Add( new Vector2(0,1)); uv2s.Add( new Vector2(1,1)); uv2s.Add( new Vector2(1,0)); uv2s.Add( new Vector2(0,0)); } //ZX + 1 face if((l_blockShape & BlockShape.PosYFace) == BlockShape.PosYFace) { vertexIndex = vertices.Count; //top left, top right, bottom right, bottom left vertices.Add(new Vector3(x+.8f, y+1 , z+.2f)); vertices.Add(new Vector3(x+.8f, y+1 , z+.8f)); vertices.Add(new Vector3(x+.2f, y+1 , z+.8f)); vertices.Add(new Vector3(x+.2f, y+1 , z+.2f)); // first triangle for the face triangles.Add(vertexIndex+3); triangles.Add(vertexIndex+1); triangles.Add(vertexIndex); // second triangle for the face triangles.Add(vertexIndex+3); triangles.Add(vertexIndex+2); triangles.Add(vertexIndex+1); //UVs for the face uvs.Add( new Vector2(0,1)); uvs.Add( new Vector2(1,1)); uvs.Add( new Vector2(1,0)); uvs.Add( new Vector2(0,0)); //UV2s (lightmapping?) uv2s.Add( new Vector2(0,1)); uv2s.Add( new Vector2(1,1)); uv2s.Add( new Vector2(1,0)); uv2s.Add( new Vector2(0,0)); } }

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  • Generating triangles from a square grid

    - by vivi
    I have a 2D square grid of values representing terrain elevations, and I want to generate triangles from that grid to make a 3D view of the terrain. My first thought was to split each square diagonally into 2 triangles, however the split diagonal can clearly be seen, especially from the top : [Sorry, as a new user I can't post images, please see here : imgur] Is there a recommended way to generate triangles to remove/reduce this effect ?

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  • Draw images with warped triangles on a web server [migrated]

    - by epologee
    The scenario The Flash front end of my current project produces images that a web server needs to combine into a video. Both frame-rate and frame-resolution are sizeable enough that sending an image sequence to the back end is not feasible (in both time and client bandwidth). Instead, we're trying to recreate the image drawing on the back end as well. Correct and slow, or incorrect and fast The problem is that this involves quite a bit of drawing textured triangles, and two solutions we found in Python (here and there) are so inefficient, that the drawing takes about 60 seconds per frame, resulting in a whopping 7,5 hours of processing time for a 30 second clip. Unacceptable. When using a PHP-module to send commands to ImageMagick for image manipulation, the whole process is super fast (tenths of a second per frame), but ImageMagick seems to be unable to draw triangles the way we do it in the front end, so the final results do not match. Unacceptable. What I'm asking here, is if there's someone who would know a way to solve this issue, by any means necessary that would run on a web server. Warping an image Let me explain the process of the front end: Perform a Delaunay calculation on points in an image to get an evenly distributed mesh of triangles. Offset the points/vertices in the mesh, distorting or warping the image. Draw the warped triangles on a new bitmap. We can send the results (coordinates) of steps 1 and 2 to the back end, to then draw the warped triangles and save it to an image on disk (or append as a frame to the video). But that last step is what I need help with. The Question Is there an alternative to ImageMagick that can draw triangles in a bitmap? Is there some other library, like a C library, that would allow us to do this? Or could we achieve this effect more easily by switching back end technologies, like Ruby? (.Net and Java are, unfortunately, not really options right now) Many thanks. EP. P.S. I'd appreciate re-tagging efforts, I don't quite know what labels to put on this question. Thanks!

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  • How does a BSP tree work for Z sorting?

    - by Jenko
    I'm developing a 3D engine in software, and so I must compute Z sorting manually. I'm currently using the painters algorithm to sort triangles and then drawing them back-to-front. This causes artifacts that I'm trying to correct. Would using a dynamic BSP-tree ensure "correct Z sorting" of triangles? Why? Because the bounding volumes of triangles would be similar? Since I would have a single "world" BSP tree, would I have to remove and re-add any moved/scaled/rotated object into the tree? Is it possible to add triangles into a BSP tree without the expensive cutting process? Why do you need to cut triangles on the axis planes anyway? Is it faster to traverse a BSP tree from any angle, than to sort all tris each draw like the painters algorithm?

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  • Problem when texturing triangles using glVertexPointer()

    - by tigrou
    I'm having a problem for displaying a single quad, here is how i do : float tex_coord[] = { 0.0, 0.0, 0.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 0.0, 0.0, 0.0 }; //how many coords should i give ? int indexes[] = { 3, 2, 0, 0, 1, 3 } float vertexes[] = { -37, 0, 30, -38, 0, 29, -41, 0, 32, -42, 0, 31 } glEnableClientState(GL_TEXTURE_COORD_ARRAY); glEnableClientState(GL_VERTEX_ARRAY); glVertexPointer(3, GL_FLOAT, 0, vertexes); glTexCoordPointer(2, GL_FLOAT, 0, tex_coord); glDrawElements(GL_TRIANGLES, 2, GL_UNSIGNED_INT, indices); glDisableClientState(GL_VERTEX_ARRAY); glDisableClientState(GL_TEXTURE_COORD_ARRAY); The result : (with 2 triangles) (with 4 triangles)

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  • Triangle - Rectangle Intersection in 2D

    - by Kevin Boyd
    I had previously asked this for 3D but now I changed my strategy and would like to do the intersection in 2D. The Rectangle is axis aligned and will always be in a fixed position, and has a constant shape and size, basically I want to clip the red areas of the triangles that extend outside the bounds of the rectangle The triangles could be in any position, shape or size, I my code I have a loop where I check the triangles one by one however I am still clueless about the math. I have identified 5 cases of triangle rectangle intersection as shown here. How do I find the intersection points of the triangle and the rectangle?

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  • What does "kTriangles/s" mean in hardware graphics benchmark reports?

    - by swquinn
    I've looked around and found several sites offering benchmarking statistics for mobile platforms and I've been seeing the unit of measure as "kTriangles/s". Originally I misread this, missing the 'k'; does this translate to "thousand(s) of triangles/s", e.g.: 8902 kTriangles/s = 8,902,000 triangles/s (I'm pretty sure that my interpretation is correct, but I hope someone can confirm this for me) Thanks!

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  • Html Buttons with Triangles [migrated]

    - by Dmitry
    I'm looking for the simplest way of creating 'buttons' with bootom-central triangles as follows: |--------| | Text | |---\/---| By buttons/menu items I mean something which will will support atomic mouse behavior for the whole shape's region. No rounded corners just the shape itself. I saw plenty of websites doing thsese buttons lately, but now for some strange reason I couldn't find any. Ideally I'm looking for tutorial links or some general guidances, as the topic might be too big to be covered by one post. Technology scope wise - ideally I'm looking for Html5/Css3 solution. I don't care mouch about old IE support and I think Html5/css3 will give a slicker/more elegant solution. On the way forward I might need to add drop shadows, which is another argument in favour of css3. Thanks.

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  • Repairing back-facing triangles without user input

    - by LTR
    My 3D application works with user-imported 3D models. Frequently, those models have a few vertices facing into the wrong direction. (For example, there is a 3D roof and a few triangles of that roof are facing inside the building). I want to repair those automatically. We can make several assumptions about these 3D models: they are completely closed without holes, and the camera is always on the outside. My idea: Shoot 500 rays from every triangle outwards into all directions. From the back side of the triangle, all rays will hit another part of the model. From the front side, at least one ray will hit nothing. Is there a better algorithm? Are there any papers about something like this?

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  • Dynamically creating astar node map by triangular polygonal map

    - by jett
    My game's map format uses a bunch of triangles to make up the platforms and terrain in 2d. Right now I can set up a 2d array of nodes for the astar algorithm that basically is a bunch of rectangles across the maps x and y that can be set to "wall" if the a* algorithm should try to go around it. However I want a function in the map loader to create the node overlay if the nodes are not specified. I was thinking if more than n percent of the a* rectangle overlaid on map was filled by polygons I could mark that entry in the array as "wall". However I'm stuck on how to do this(or even start) where/when the triangles can be overlapping and also of variable size.

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  • Drawing a textured triangle with CPU instead of GPU

    - by Jenko
    I understand the benefits of GPU rendering and such, but for a certain limited application I need to render textured triangles purely using CPU. I've built a 3D engine capable of object handling, transform, projection, culling and the likes ... now all I need is a little code snippet that draws a single textured triangle onto a bitmap... any language accepted! Inputs: Texture bitmap, Triangle U/V/W coords, Triangle X/Y screen coords Output: The textured triangle drawn at the given screen coords I've currently been using a platform function to draw triangles to screen, but I'm looking to handle it myself to speeden up the process.

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  • Forming triangles from points and relations

    - by SiN
    Hello, I want to generate triangles from points and optional relations between them. Not all points form triangles, but many of them do. In the initial structure, I've got a database with the following tables: Nodes(id, value) Relations(id, nodeA, nodeB, value) Triangles(id, relation1_id, relation2_id, relation3_id) In order to generate triangles from both nodes and relations table, I've used the following query: INSERT INTO Triangles SELECT t1.id, t2.id , t3.id, FROM Relations t1, Relations t2, Relations t3 WHERE t1.id < t2.id AND t3.id > t1.id AND ( t1.nodeA = t2.nodeA AND (t3.nodeA = t1.nodeB AND t3.nodeB = t2.nodeB OR t3.nodeA = t2.nodeB AND t3.nodeB = t1.nodeB) OR t1.nodeA = t2.nodeB AND (t3.nodeA = t1.nodeB AND t3.nodeB = t2.nodeA OR t3.nodeA = t2.nodeA AND t3.nodeB = t1.nodeB) ) It's working perfectly on small sized data. (~< 50 points) In some cases however, I've got around 100 points all related to each other which leads to thousands of relations. So when the expected number of triangles is in the hundreds of thousands, or even in the millions, the query might take several hours. My main problem is not in the select query, while I see it execute in Management Studio, the returned results slow. I received around 2000 rows per minute, which is not acceptable for my case. As a matter of fact, the size of operations is being added up exponentionally and that is terribly affecting the performance. I've tried doing it as a LINQ to object from my code, but the performance was even worse. I've also tried using SqlBulkCopy on a reader from C# on the result, also with no luck. So the question is... Any ideas or workarounds?

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  • Geometry Shader : points + Triangles

    - by CmasterG
    I have different Shaders and for each Shader a instance of the ShaderClass class, which initializes the Shaders, Renders the Shaders, etc. I use most of the Shaderclasses without Geometry Shader, but in one Shader Class i also use a Geometry Shader. The problem is, that when I render one object with the Shaderclass that uses the Geometry shader, all other object are rendered with the same geometry that I create in the Geometry Shader. Can you help me? Is it possible that I have to use a Geometry Shader for each object, when I use one for one object? I use DirectX 11 with C++.

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  • Merge overlapping triangles into a polygon

    - by nornagon
    I've got a bunch of overlapping triangles from a 3D model projected into a 2D plane. I need to merge each island of touching triangles into a closed, non-convex polygon. The resultant polygons shouldn't have any holes in them (since the source data doesn't). Many of the source triangles share (floating point identical) edges with other triangles in the source data. What's the easiest way to do this? Performance isn't particularly important, since this will be done at design time.

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  • Mesh with quads to triangle mesh

    - by scape
    I want to use Blender for making models yet realize some of the polygons are not triangles but contain quads or more (example: cylinder top and bottom). I could export the the mesh as a basic mesh file and import it in to an openGL application and workout rendering the quads as tris, but anything with more than 4 vert indices is beyond me. Is it typical to convert the mesh to a triangle-based mesh inside blender before exporting it? I actually tried this through the quads_convert_to_tris method within a blender py script and the top of the cylinder does not look symmetrical. What is typically done to render a loaded mesh as a tri?

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  • Fast software color interpolating triangle rasterization technique

    - by Belgin
    I'm implementing a software renderer with this rasterization method, however, I was wondering if there is a possibility to improve it, or if there exists an alternative technique that is much faster. I'm specifically interested in rendering small triangles, like the ones from this 100k poly dragon: As you can see, the method I'm using is not perfect either, as it leaves small gaps from time to time (at least I think that's what's happening). I don't mind using assembly optimizations. Pseudocode or actual code (C/C++ or similar) is appreciated. Thanks in advance.

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  • Issue with a point coordinates, which creates an unwanted triangle

    - by Paul
    I would like to connect the points from the red path, to the y-axis in blue. I figured out that the problem with my triangles came from the first point (V0) : it is not located where it should be. In the console, it says its location is at 0,0, but in the emulator, it is not. The code : for(int i = 1; i < 2; i++) { CCLOG(@"_polyVertices[i-1].x : %f, _polyVertices[i-1].y : %f", _polyVertices[i-1].x, _polyVertices[i-1].y); CCLOG(@"_polyVertices[i].x : %f, _polyVertices[i].y : %f", _polyVertices[i].x, _polyVertices[i].y); ccDrawLine(_polyVertices[i-1], _polyVertices[i]); } The output : _polyVertices[i-1].x : 0.000000, _polyVertices[i-1].y : 0.000000 _polyVertices[i].x : 50.000000, _polyVertices[i].y : 0.000000 And the result : (the layer goes up, i could not take the screenshot before the layer started to go up, but the first red point starts at y=0) : Then it creates an unwanted triangle when the code continues : Would you have any idea about this? (So to force the first blue point to start at 0,0, and not at 50,0 as it seems to be now) Here is the code : - (void)generatePath{ float x = 50; //first red point float y = 0; for(int i = 0; i < kMaxKeyPoints+1; i++) { if (i<3){ _hillKeyPoints[i] = CGPointMake(x, y); x = 150 + (random() % (int) 30); y += -40; } else if(i<20){ //going right _hillKeyPoints[i] = CGPointMake(x, y); x += (random() % (int) 30); y += -40; } else if(i<25){ //stabilize _hillKeyPoints[i] = CGPointMake(x, y); x = 150 + (random() % (int) 30); y += -40; } else if(i<30){ //going left _hillKeyPoints[i] = CGPointMake(x, y); //x -= (random() % (int) 10); x = 150 + (random() % (int) 30); y += -40; } else { //back to normal _hillKeyPoints[i] = CGPointMake(x, y); x = 150 + (random() % (int) 30); y += -40; } } } -(void)generatePolygons{ static int prevFromKeyPointI = -1; static int prevToKeyPointI = -1; // key points interval for drawing while (_hillKeyPoints[_fromKeyPointI].y > -_offsetY+winSizeTop) { _fromKeyPointI++; } while (_hillKeyPoints[_toKeyPointI].y > -_offsetY-winSizeBottom) { _toKeyPointI++; } if (prevFromKeyPointI != _fromKeyPointI || prevToKeyPointI != _toKeyPointI) { _nPolyVertices = 0; float x1 = 0; int keyPoints = _fromKeyPointI; for (int i=_fromKeyPointI; i<_toKeyPointI; i++){ //V0: at (0,0) _polyVertices[_nPolyVertices] = CGPointMake(x1, y1); //first blue point _polyTexCoords[_nPolyVertices++] = CGPointMake(x1, y1); //V1: to the first "point" _polyVertices[_nPolyVertices] = CGPointMake(_hillKeyPoints[keyPoints].x, _hillKeyPoints[keyPoints].y); _polyTexCoords[_nPolyVertices++] = CGPointMake(_hillKeyPoints[keyPoints].x, _hillKeyPoints[keyPoints].y); keyPoints++; //from point at index 0 to 1 //V2, same y as point n°2: _polyVertices[_nPolyVertices] = CGPointMake(0, _hillKeyPoints[keyPoints].y); _polyTexCoords[_nPolyVertices++] = CGPointMake(0, _hillKeyPoints[keyPoints].y); //V1 again _polyVertices[_nPolyVertices] = _polyVertices[_nPolyVertices-2]; _polyTexCoords[_nPolyVertices++] = _polyVertices[_nPolyVertices-2]; //V2 again _polyVertices[_nPolyVertices] = _polyVertices[_nPolyVertices-2]; _polyTexCoords[_nPolyVertices++] = _polyVertices[_nPolyVertices-2]; //CCLOG(@"_nPolyVertices V2 again : %i", _nPolyVertices); //V3 = same x,y as point at index 1 _polyVertices[_nPolyVertices] = CGPointMake(_hillKeyPoints[keyPoints].x, _hillKeyPoints[keyPoints].y); _polyTexCoords[_nPolyVertices] = CGPointMake(_hillKeyPoints[keyPoints].x, _hillKeyPoints[keyPoints].y); y1 = _polyVertices[_nPolyVertices].y; _nPolyVertices++; } prevFromKeyPointI = _fromKeyPointI; prevToKeyPointI = _toKeyPointI; } } - (void) draw { //RED glColor4f(1, 1, 1, 1); for(int i = MAX(_fromKeyPointI, 1); i <= _toKeyPointI; ++i) { glColor4f(1.0, 0, 0, 1.0); ccDrawLine(_hillKeyPoints[i-1], _hillKeyPoints[i]); } //BLUE glColor4f(0, 0, 1, 1); for(int i = 1; i < 2; i++) { CCLOG(@"_polyVertices[i-1].x : %f, _polyVertices[i-1].y : %f", _polyVertices[i-1].x, _polyVertices[i-1].y); CCLOG(@"_polyVertices[i].x : %f, _polyVertices[i].y : %f", _polyVertices[i].x, _polyVertices[i].y); ccDrawLine(_polyVertices[i-1], _polyVertices[i]); } } Thanks

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  • Firefox 17 and CSS borders based triangles = crap

    - by Adeher
    Like many front-end devs, I've been using the border trick to render triangles in CSS. http://apps.eky.hk/css-triangle-generator/ this generator helps with the technique. Today, like every week (almost), the Firefox team released a new version without any clear changelog on the rendering engine. Now we can see an ungraceful gray border around those triangles. I haven't found a trick to get rid of it yet. On top of that, before Firefox 17, when people were complaining about how aliased those triangles looked, an additional trick was to set the border-style property to "dashed" instead of solid. Using firebug on the triangle generator, you can quickly see how it shows up now, and cry yourself to death. I hope a more brillant front-end dev than myself will find a fix for this and share it here. Thanks

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  • Find the number of congruent triangles?

    - by avd
    Say I have a square from (0,0) to (z,z). Given a triangle within this square which has integer coordinates for all its vertices. Find out the number of triangles within this square which are congruent to this triangle and have integer coordinates. My algorithm is as follows-- 1) Find out the minimum bounding rectangle(MBR) for the given triangle. 2) Find out the number of congruent triangles, y within that MBR, obtained after reflection, rotation of the given triangle. y can be either 2,4 or 8. 3) Now find out how many such MBR's can be drawn within the given big square, say x; (This is similar to finding number of squares on a chess board) 4) x*y is the required answer. Am I counting some triangles more than once or I am missing something by this algorithm? It is a problem on online judge? It gives me wrong answer. I have thought a lot about it, but I am not able to figure it out.

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  • Polygonal Triangulation - algorithm with O(n log n) complexity

    - by Arthur Wulf White
    I wish to triangulate a polygon I only have the outline of (p0, p1, p2 ... pn) like described in this question: polygon triangulation algorithm and this webpage: http://cgm.cs.mcgill.ca/~godfried/teaching/cg-projects/97/Ian/algorithm2.html I do not wish to learn the subject and have a deep understanding of it at the moment. I only want to see an effective algorithm that can be used out of the box. The one described in the site seems to be of somewhat high complexity O(n) for finding one ear. I heard this could be done in O(n log n) time. Is there any well known easy to use algorithm that I can translate port to use in my engine that runs with somewhat reasonable complexity? The reason I need to triangulate is that I wish to feel out a 2d-outline and render it 3d. Much like we fill out a 2d-outline in paint. I could use sprites. This would not serve cause I am planning to play with the resulting model on the z-axis, giving it different heights in the different areas. I would love to try the books that were mentioned, although I suspect that is not the answer most readers are hoping for when they read this Q & A format. Mostly I like to see a code snippet I can cut and paste with some modifications and start running.

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