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  • What should I worry about when changing OpenGL origin to upper left of screen?

    - by derivative
    For self education, I'm writing a 2D platformer engine in C++ using SDL / OpenGL. I initially began with pure SDL using the tutorials on sdltutorials.com and lazyfoo.net, but I'm now rendering in an OpenGL context (specifically immediate mode but I'm learning about VAOs/VBOs) and using SDL for interface, audio, etc. SDL uses a coordinate system with the origin in the upper left of the screen and the positive y-axis pointing down. It's easy to set up my orthographic projection in OpenGL to mirror this. I know that texture coordinates are a right-hand system with values from 0 to 1 -- flipping the texture vertically before rendering (well, flip the file before loading) yields textures that render correctly... which is fine if I'm drawing the entire texture, but ultimately I'll be using tilesets and can imagine problems. What should I be concerned about in terms of rendering when I do this? If anybody has any advice or they've done this themselves and can point out future pitfalls, that would be great, but really any thoughts would be appreciated.

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  • Isometric algorithm [fixed]

    - by David
    so i've been toying with isometric and i just cant get the tiles to be in the right order. im probably missing something obvious and i just cant see it... but even at the risk of looking stupid, heres my code. for (int i = 0; i < Tile.MapSize; i++) { for (int j = 0; j < Tile.MapSize; j++) { spriteBatch.Draw( Tile.TileSetTexture, new Rectangle( (-j * Tile.TileWidth / 2) + (i * Tile.TileWidth / 2), (i * (Tile.TileHeight - 9) / 2) - (-j * (Tile.TileHeight - 9) / 2), Tile.TileWidth, Tile.TileHeight), Tile.GetSourceRectangle(tileID), Color.White, 0.0f, new Vector2(-350, -60), SpriteEffects.None, 1.0f); } } and heres what i end up with delicious messed up map yep, bit of an issue. so if anyone could help, i'd appreciate it. edit* works now <_<

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  • How change LOD in geometry?

    - by ChaosDev
    Im looking for simple algorithm of LOD, for change geometry vertexes and decrease frame time. Im created octree, but now I want model or terrain vertex modify algorithm,not for increase(looking on tessellation later) but for decrease. I want something like this Questions: Is same algorithm can apply either to model and terrain correctly? Indexes need to be modified ? I must use octree or simple check distance between camera and object for desired effect ? New value of indexcount for DrawIndexed function needed ? Code: //m_LOD == 10 in the beginning //m_RawVerts - array of 3d Vector filled with values from vertex buffer. void DecreaseLOD() { m_LOD--; if(m_LOD<1)m_LOD=1; RebuildGeometry(); } void IncreaseLOD() { m_LOD++; if(m_LOD>10)m_LOD=10; RebuildGeometry(); } void RebuildGeometry() { void* vertexRawData = new byte[m_VertexBufferSize]; void* indexRawData = new DWORD[m_IndexCount]; auto context = mp_D3D->mp_Context; D3D11_MAPPED_SUBRESOURCE data; ZeroMemory(&data,sizeof(D3D11_MAPPED_SUBRESOURCE)); context->Map(mp_VertexBuffer->mp_buffer,0,D3D11_MAP_READ,0,&data); memcpy(vertexRawData,data.pData,m_VertexBufferSize); context->Unmap(mp_VertexBuffer->mp_buffer,0); context->Map(mp_IndexBuffer->mp_buffer,0,D3D11_MAP_READ,0,&data); memcpy(indexRawData,data.pData,m_IndexBufferSize); context->Unmap(mp_IndexBuffer->mp_buffer,0); DWORD* dwI = (DWORD*)indexRawData; int sz = (m_VertexStride/sizeof(float));//size of vertex element //algorithm must be here. std::vector<Vector3d> vertices; int i = 0; for(int j = 0; j < m_VertexCount; j++) { float x1 = (((float*)vertexRawData)[0+i]); float y1 = (((float*)vertexRawData)[1+i]); float z1 = (((float*)vertexRawData)[2+i]); Vector3d lv = Vector3d(x1,y1,z1); //my useless attempts if(j+m_LOD+1<m_RawVerts.size()) { float v1 = VECTORHELPER::Distance(m_RawVerts[dwI[j]],m_RawVerts[dwI[j+m_LOD]]); float v2 = VECTORHELPER::Distance(m_RawVerts[dwI[j]],m_RawVerts[dwI[j+m_LOD+1]]); if(v1>v2) lv = m_RawVerts[dwI[j+1]]; else if(v2<v1) lv = m_RawVerts[dwI[j+2]]; } (((float*)vertexRawData)[0+i]) = lv.x; (((float*)vertexRawData)[1+i]) = lv.y; (((float*)vertexRawData)[2+i]) = lv.z; i+=sz;//pass others vertex format values without change } for(int j = 0; j < m_IndexCount; j++) { //indices ? } //set vertexes to device UpdateVertexes(vertexRawData,mp_VertexBuffer->getSize()); delete[] vertexRawData; delete[] indexRawData; }

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  • How to implement explosion in OpenGL with a particle effect?

    - by Chan
    I'm relatively new to OpenGL and I'm clueless how to implement explosion. So could anyone give me some ideas how to start? Suppose the explosion occurs at location $(x, y, z)$, then I'm thinking of randomly generate a collection of vectors with $(x, y, z)$ as origin, then draw some particle (glutSolidCube) which move along this vector for some period of time, says after 1000 updates, it disappear. Is this approach feasible? A minimal example would be greatly appreciated.

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  • How to make an object move again after being stopped by collision in Unity?

    - by Matthew Underwood
    I have a player object which position is always centered on the main camera's viewport. This object has a Rigidbody 2D, a box and circle collider. The player moves around a level, the level has a polygon collider attached. I move the camera until the object hits against the collider, which stops the movement of the camera by setting its speed to 0. The problem happens when I want to move the camera / player object away from the collider. As the speed is already at 0, it cannot move away from the collider. The script attached to the player object, checks for collisions and applies the speed to 0 on the main camera's test script. using UnityEngine; using System.Collections; public class move : MonoBehaviour { public float speed; public test testing; // Use this for initialization void Start () { speed = 10F; testing = Camera.main.GetComponent<test>(); } // Update is called once per frame void FixedUpdate () { Vector3 p = Camera.main.ViewportToWorldPoint(new Vector3(0.5F, 0.5F, Camera.main.nearClipPlane)); transform.position = new Vector3(p.x, p.y, -1); } void OnCollisionEnter2D(Collision2D col) { testing.speed = 0; } void OnCollisionExit2D(Collision2D col) { testing.speed = 10F; } } This is the script attached to the main camera; just a simple script that changes the camera's position. using UnityEngine; using System.Collections; public class test : MonoBehaviour { public float speed; public float translationY; public float translationX; // Use this for initialization void Start () { speed = 10F; } void FixedUpdate () { translationY = Input.GetAxis("Vertical") * speed * Time.deltaTime; translationX = Input.GetAxis("Horizontal") * speed * Time.deltaTime; transform.Translate(translationX, translationY, 0); } } The player object isn't kinematic and is a fixed angle, the colliders aren't triggers and the polygon collider isn't a trigger either. The player is the red square, the collider is the pink area. -- EDIT -- From the latest change the collider set up for the player So if the X speed was disabled. It wouldnt move into the side of the polygon colider which is good, but yet you couldnt move away from it. And moving down would move inside the colider.

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  • Behaviour tree code example?

    - by jokoon
    http://altdevblogaday.org/2011/02/24/introduction-to-behavior-trees/ Obviously the most interesting article I found on this website. What do you think about it ? It lacks some code example, don't you know any ? I also read that state machines are not very flexible compared to behaviour trees... On top of that I'm not sure if there is a true link between state machines and the state pattern... is there ?

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  • Image 1 becomes image 2 with sliding effect from left to right?

    - by Paul
    I would like to show a second image appearing while a "door" is closing on my character. I've got my character in the middle of the screen and a door coming from the left. When the door passes my character, I would like to have this second image appearing little by little. So far, I've gotten by with fadingOut the character and then fadingIn my second image of the character at the same position when the door is completely closed, but I would like to have both of them at the same time. (the effect that image 1 becomes image 2 when the door is sliding from left to right). Would you know how to do this with Cocos2d? Here are the images : at first, the character is blue, and the door is coming from the left : Then, behind the black door, the character becomes red, but only behind this door, so it stays blue when the door is not on him, and will become completely red when the door passes the character : EDIT : with this code, the black door hides the red and blue rectangles : (And if i add each of my layers at a different depth, and only use GL_LESS, same thing) blue.position = ccp( size.width*0.5 , size.height/2 ); red.position = ccp( size.width*0.46 , size.height/2 ); black.position = ccp( size.width*0.1 , size.height/2 ); glEnable(GL_DEPTH_TEST); [batch addChild:red z:0]; [batch addChild:black z:2]; glDepthFunc(GL_GREATER); [batch addChild:blue z:1]; glDepthFunc(GL_LESS); id action1 = [CCMoveTo actionWithDuration:3 position:ccp(size.width,size.height/2)]; [black runAction: [CCSequence actions:action1, nil]];

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  • Collision within a poly

    - by G1i1ch
    For an html5 engine I'm making, for speed I'm using a path poly. I'm having trouble trying to find ways to get collision with the walls of the poly. To make it simple I just have a vector for the object and an array of vectors for the poly. I'm using Cartesian vectors and they're 2d. Say poly = [[550,0],[169,523],[-444,323],[-444,-323],[169,-523]], it's just a pentagon I generated. The object that will collide is object, object.pos is it's position and object.vel is it's velocity. They're both 2d vectors too. I've had some success to get it to find a collision, but it's just black box code I ripped from a c++ example. It's very obscure inside and all it does though is return true/false and doesn't return what vertices are collided or collision point, I'd really like to be able to understand this and make my own so I can have more meaningful collision. I'll tackle that later though. Again the question is just how does one find a collision to walls of a poly given you know the poly vertices and the object's position + velocity? If more info is needed please let me know. And if all anyone can do is point me to the right direction that's great.

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  • Which opcodes are faster at the CPU level?

    - by Geotarget
    In every programming language there are sets of opcodes that are recommended over others. I've tried to list them here, in order of speed. Bitwise Integer Addition / Subtraction Integer Multiplication / Division Comparison Control flow Float Addition / Subtraction Float Multiplication / Division Where you need high-performance code, C++ can be hand optimized in assembly, to use SIMD instructions or more efficient control flow, data types, etc. So I'm trying to understand if the data type (int32 / float32 / float64) or the operation used (*, +, &) affects performance at the CPU level. Is a single multiply slower on the CPU than an addition? In MCU theory you learn that speed of opcodes is determined by the number of CPU cycles it takes to execute. So does it mean that multiply takes 4 cycles and add takes 2? Exactly what are the speed characteristics of the basic math and control flow opcodes? If two opcodes take the same number of cycles to execute, then both can be used interchangeably without any performance gain / loss? Any other technical details you can share regarding x86 CPU performance is appreciated

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  • Unable to Call Instantiate in Class Member Function

    - by onguarde
    The following javascript is attached to a gameObject. var instance : GameObject; class eg_class { function eg_func(){ var thePrefab : GameObject; instance = Instantiate(thePrefab); } } Error, Unknown identifier: 'instance'. Unknown identifier: 'Instantiate'. Questions, 1) Why is it that "instance" cannot be accessed within a class? Isn't it supposed to be a public variable? 2) "Instantiate" function works in Start()/Update() root functions. Is there a way to make it work from within member functions? Thanks in advance!

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  • Tile-wide extent tracing on a grid.

    - by Larolaro
    I'm currently working on A* pathfinding on a grid and I'm looking to smooth the generated path, while also considering the extent of the character moving along it. I'm using a grid for the pathfinding, however character movement is free roaming, not strict tile to tile movement. To achieve a smoother, more efficient path, I'm doing line traces on a grid to determine if there is unwalkable tiles between tiles to shave off unecessary corners. However, because a line trace is zero extent, it doesn't consider the extent of the character and gives bad results (not returning unwalkable tiles just missed by the line, causing unwanted collisions). So what I'm looking for is rather than a line algorithm that determines the tiles under it, I'm looking for one that determines the tiles under a tile-wide extent line. Here is an image to help visualise my problem! Does anyone have any ideas? I've been working with Bresenham's line and other alternatives but I haven't yet figured out how to nail this specific problem.

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  • OpenGL setup on Windows

    - by kevin james
    I have been trying to use OpenGL for two days now. First on Mac, then on Windows. The problem with Mac is that it doesn't support the newer versions of OpenGL. I ran a tutorial that actually did get some things working, but it only works in XCode (i.e., I can't create a new file, paste in the same code, and get it to work). Because of these issues, I moved to Windows. My Windows 7 has OpenGL 4.3, which is the same that is used in alot of other tutorials. However, not one of these tutorials gives any instruction on how to set it up for the first time. I have come across some vague posts saying that some libraries need to be linked. But WHAT libraries, and HOW do I link them? Please help. I am pretty desperate to set this up as this project is due for work soon. I have actually used OpenGL before at my university, but the computers already had everything set up. The project itself is very easy, but setting up OpenGL is not something I know how to do.

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  • Omni-directional light shadow mapping with cubemaps in WebGL

    - by Winged
    First of all I must say, that I have read a lot of posts describing an usage of cubemaps, but I'm still confused about how to use them. My goal is to achieve a simple omni-directional (point) light type shading in my WebGL application. I know that there is a lot more techniques (like using Two-Hemispheres or Camera Space Shadow Mapping) which are way more efficient, but for an educational purpose cubemaps are my primary goal. Till now, I have adapted a simple shadow mapping which works with spotlights (with one exception: I don't know how to cut off the glitchy part beyond the reach of a single shadow map texture): glitchy shadow mapping<<< So for now, this is how I understand the usage of cubemaps in shadow mapping: Setup a framebuffer (in case of cubemaps - 6 framebuffers; 6 instead of 1 because every usage of framebufferTexture2D slows down an execution which is nicely described here <<<) and a texture cubemap. Also in WebGL depth components are not well supported, so I need to render it to RGBA first. this.texture = gl.createTexture(); gl.bindTexture(gl.TEXTURE_CUBE_MAP, this.texture); gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MIN_FILTER, gl.LINEAR); gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MAG_FILTER, gl.LINEAR); for (var face = 0; face < 6; face++) gl.texImage2D(gl.TEXTURE_CUBE_MAP_POSITIVE_X + face, 0, gl.RGBA, this.size, this.size, 0, gl.RGBA, gl.UNSIGNED_BYTE, null); gl.bindTexture(gl.TEXTURE_CUBE_MAP, null); this.framebuffer = []; for (face = 0; face < 6; face++) { this.framebuffer[face] = gl.createFramebuffer(); gl.bindFramebuffer(gl.FRAMEBUFFER, this.framebuffer[face]); gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_CUBE_MAP_POSITIVE_X + face, this.texture, 0); gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, this.depthbuffer); var e = gl.checkFramebufferStatus(gl.FRAMEBUFFER); // Check for errors if (e !== gl.FRAMEBUFFER_COMPLETE) throw "Cubemap framebuffer object is incomplete: " + e.toString(); } Setup the light and the camera (I'm not sure if should I store all of 6 view matrices and send them to shaders later, or is there a way to do it with just one view matrix). Render the scene 6 times from the light's position, each time in another direction (X, -X, Y, -Y, Z, -Z) for (var face = 0; face < 6; face++) { gl.bindFramebuffer(gl.FRAMEBUFFER, shadow.buffer.framebuffer[face]); gl.viewport(0, 0, shadow.buffer.size, shadow.buffer.size); gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT); camera.lookAt( light.position.add( cubeMapDirections[face] ) ); scene.draw(shadow.program); } In a second pass, calculate the projection a a current vertex using light's projection and view matrix. Now I don't know If should I calculate 6 of them, because of 6 faces of a cubemap. ScaleMatrix pushes the projected vertex into the 0.0 - 1.0 region. vDepthPosition = ScaleMatrix * uPMatrixFromLight * uVMatrixFromLight * vWorldVertex; In a fragment shader calculate the distance between the current vertex and the light position and check if it's deeper then the depth information read from earlier rendered shadow map. I know how to do it with a 2D Texture, but I have no idea how should I use cubemap texture here. I have read that texture lookups into cubemaps are performed by a normal vector instead of a UV coordinate. What vector should I use? Just a normalized vector pointing to the current vertex? For now, my code for this part looks like this (not working yet): float shadow = 1.0; vec3 depth = vDepthPosition.xyz / vDepthPosition.w; depth.z = length(vWorldVertex.xyz - uLightPosition) * linearDepthConstant; float shadowDepth = unpack(textureCube(uDepthMapSampler, vWorldVertex.xyz)); if (depth.z > shadowDepth) shadow = 0.5; Could you give me some hints or examples (preferably in WebGL code) how I should build it?

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  • Building View Matrix in Direct3D11

    - by Balls
    Am I doing it right? I converted this. m_ViewMatrix = XMMatrixLookAtLH(XMLoadFloat3(&m_Position), lookAtVector, upVector); to this one. XMVECTOR vz = XMVector3Normalize( lookAtVector - XMLoadFloat3(&m_Position) ); XMVECTOR vx = XMVector3Normalize( XMVector3Cross( upVector, vz ) ); XMVECTOR vy = XMVector3Cross( vz, vx ); m_ViewMatrix.r[0] = vx; m_ViewMatrix.r[1] = vy; m_ViewMatrix.r[2] = vz; m_ViewMatrix.r[3] = XMLoadFloat3(&m_Position); m_ViewMatrix.r[0].m128_f32[3] = 0.0f; m_ViewMatrix.r[1].m128_f32[3] = 0.0f; m_ViewMatrix.r[2].m128_f32[3] = 0.0f; m_ViewMatrix.r[3].m128_f32[3] = 1.0f; m_ViewMatrix = XMMatrixInverse( &XMMatrixDeterminant(m_ViewMatrix), m_ViewMatrix ); Everything looks fine when I run it. Another question is, I saw on this site(http://webglfactory.blogspot.com/2011/06/how-to-create-view-matrix.html) that he subtracted lookat from position in his vector vz. I tried it but gave me wrong view matrix. Can anyone check my code. I'm studying linear algebra right now. Sucks my course doesn't have one. Thank you, Balls

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  • Creating a voxel chunk with a VBO - How to translate the coordinates of each block and add it to the VBO chunk?

    - by sunsunsunsunsun
    Im trying to make a voxel engine similar to minecraft as a little learning experience and a way to learn some opengl. I have created a chunk class and I want to put all of the vertices for the whole chunk into a single VBO. I was previously only putting each block into a vbo and making a call to render each block. Anyways, I am a bit confused about how I can translate the coordinates of each block in the chunk when I'm putting all vertices into one vbo. This is what I have at the moment. public void putVertices(float tx, float ty, float tz) { float l_length = 1.0f; float l_height = 1.0f; float l_width = 1.0f; vertexPositionData.put(new float[]{ xOffset + l_length + tx, l_height + ty, zOffset + -l_width + tz, xOffset + -l_length + tx, l_height + ty, zOffset + -l_width + tz, xOffset + -l_length + tx, l_height + ty, zOffset + l_width + tz, xOffset + l_length + tx, l_height + ty, zOffset + l_width + tz, xOffset + l_length + tx, -l_height + ty, zOffset + l_width + tz, xOffset + -l_length + tx, -l_height + ty, zOffset + l_width + tz, xOffset + -l_length + tx, -l_height + ty, zOffset + -l_width + tz, xOffset + l_length + tx, -l_height + ty, zOffset + -l_width + tz, xOffset + l_length + tx, l_height + ty, zOffset + l_width + tz, xOffset + -l_length + tx, l_height + ty,zOffset + l_width + tz, xOffset + -l_length + tx, -l_height + ty,zOffset + l_width + tz, xOffset + l_length + tx, -l_height + ty, zOffset + l_width + tz, xOffset + l_length + tx, -l_height + ty, zOffset + -l_width + tz, xOffset + -l_length + tx, -l_height + ty,zOffset + -l_width + tz, xOffset + -l_length + tx, l_height + ty, zOffset + -l_width + tz, xOffset + l_length + tx, l_height + ty, zOffset + -l_width + tz, xOffset + -l_length + tx, l_height + ty, zOffset + l_width + tz, xOffset + -l_length + tx, l_height + ty, zOffset + -l_width + tz, xOffset + -l_length + tx, -l_height + ty, zOffset + -l_width + tz, xOffset + -l_length + tx, -l_height + ty,zOffset + l_width + tz, xOffset + l_length + tx, l_height + ty,zOffset + -l_width + tz, xOffset + l_length + tx, l_height + ty, zOffset + l_width + tz, xOffset + l_length + tx, -l_height + ty, zOffset + l_width + tz, xOffset + l_length + tx, -l_height + ty, zOffset + -l_width + tz }); } public void createChunk() { vertexPositionData = BufferUtils.createFloatBuffer((24*3)*activateBlocks); Random random = new Random(); for (int x = 0; x < CHUNK_SIZE; x++) { for (int y = 0; y < CHUNK_SIZE; y++) { for (int z = 0; z < CHUNK_SIZE; z++) { if(blocks[x][y][z].getActive()) { putVertices(x*2.0f, y*2.0f, z*2.0f); } } } } Whats any easy way to translate the vertices of each block into its correct position? I was previously using glTranslatef with each call to render block but this wont work now. What I am doing now also does not work, the blocks all render in stacks on top of each other and it looks like this: http://i.imgur.com/NyFtBTI.png Thanks

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  • Incorrect results for frustum cull

    - by DeadMG
    Previously, I had a problem with my frustum culling producing too optimistic results- that is, including many objects that were not in the view volume. Now I have refactored that code and produced a cull that should be accurate to the actual frustum, instead of an axis-aligned box approximation. The problem is that now it never returns anything to be in the view volume. As the mathematical support library I'm using does not provide plane support functions, I had to code much of this functionality myself, and I'm not really the mathematical type, so it's likely that I've made some silly error somewhere. As follows is the relevant code: class Plane { public: Plane() { r0 = Math::Vector(0,0,0); normal = Math::Vector(0,1,0); } Plane(Math::Vector p1, Math::Vector p2, Math::Vector p3) { r0 = p1; normal = Math::Cross((p2 - p1), (p3 - p1)); } Math::Vector r0; Math::Vector normal; }; This class represents one plane as a point and a normal vector. class Frustum { public: Frustum( const std::array<Math::Vector, 8>& points ) { planes[0] = Plane(points[0], points[1], points[2]); planes[1] = Plane(points[4], points[5], points[6]); planes[2] = Plane(points[0], points[1], points[4]); planes[3] = Plane(points[2], points[3], points[6]); planes[4] = Plane(points[0], points[2], points[4]); planes[5] = Plane(points[1], points[3], points[5]); } Plane planes[6]; }; The points are passed in order where (the inverse of) each bit of the index of each point indicates whether it's the left, top, and back of the frustum, respectively. As such, I just picked any three points where they all shared one bit in common to define the planes. My intersection test is as follows (based on this): bool Intersects(Math::AABB lhs, const Frustum& rhs) const { for(int i = 0; i < 6; i++) { Math::Vector pvertex = lhs.TopRightFurthest; Math::Vector nvertex = lhs.BottomLeftClosest; if (rhs.planes[i].normal.x <= -0.0f) { std::swap(pvertex.x, nvertex.x); } if (rhs.planes[i].normal.y <= -0.0f) { std::swap(pvertex.y, nvertex.y); } if (rhs.planes[i].normal.z <= -0.0f) { std::swap(pvertex.z, nvertex.z); } if (Math::Dot(rhs.planes[i].r0, nvertex) < 0.0f) { return false; } } return true; } Also of note is that because I'm using a left-handed co-ordinate system, I wrote my Cross function to return the negative of the formula given on Wikipedia. Any suggestions as to where I've made a mistake?

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  • Circle collision detection and Vector math: HELP?

    - by Griffin
    Hey so i'm currently going through the wildbunny blog to learn about collision detection, but i'm a bit confused on how the vectors he's talking about come into play QUOTED BLOG: p = ||A-B|| – (r1+r2) The two spheres are penetrating by distance p. We would also like the penetration vector so that we can correct the penetration once we discover it. This is the vector that moves both circles to the point where they just touch, correcting the penetration. Importantly it is not only just a vector that does this, it is the only vector which corrects the penetration by moving the minimum amount. This is important because we only want to correct the error, not introduce more by moving too much when we correct, or too little. N = (A-B) / ||A-B|| P = N*p Here we have calculated the normalised vector N between the two centres and the penetration vector P by multiplying our unit direction by the penetration distance. Ok so i understand that p is the distance each circle is penetrating each other, but i don't get what exactly N and P is. it seems to me N is just the coordinates of the 3rd point of the right trianlge formed by point A and B (A-B) then being divided by the hypotenuse of that triangle or distance between A and B (||A-B||) Whats the significance of this? Also, what is the penetration vector used for? It seems to me like a movement that one of the circles would perform to get un-penetrated.

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  • Calculate the intersection depth between a rectangle and a right triangle

    - by Celarix
    all. I'm working on a 2D platformer built in C#/XNA, and I'm having a lot of problems calculating the intersection depth between a standard rectangle (used for sprites) and a right triangle (used for sloping tiles). Ideally, the rectangle will collide with the solid edges of the triangle, and its bottom-center point will collide with the sloped edge. I've been fighting with this for a couple of days now, and I can't make sense of it. So far, the method detects intersections (somewhat), but it reports wildly wrong depths. How does one properly calculate the depth? Is there something I'm missing? Thanks!

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  • Sorting objects before rendering

    - by dreta
    I'm trying to implement a scene graph and in all the articles i've come across there is talk about object sorting. So you'd sort your objects by "material" for example. Now untill i sat down and started implementing it, i kind of took this for granted, because it made sense. But now i'm wondering what does sorting actually change? In my engine, i have a manager for UBOs, i use those to store data that'll be shared between programs, at the moment that only involves time, camera and projection matrices and lights (i'm not worrying about managing which lights affect which objects ATM). Now for each model i have to change the model to world matrix uniform, no sorting is going to change that. So is the jump from changing this matrix to also setting a material for each object that bad? I vaguely remember reading somewhere that each time you change something in the pipeline, it has to get flushed and that can cause performance issues. But for each drawing call i'm setting up a model to world matrix anyway, so what sense does it make to ever be concerned about this? BTW is there any information about whether changing a uniform and calling glBufferSubData is more (or less) expensive.

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  • Drawing 2D Grid in 3D View - Need help with method

    - by Deukalion
    I'm trying to draw a simple 2D grid for an editor, to able to navigate more clearly around the 3D space, but I can't render it: Grid2D class, creates a grid of a certain size at a location and should just draw lines. public class Grid2D : IShape { private VertexPositionColor[] _vertices; private Vector2 _size; private Vector3 _location; private int _faces; public Grid2D(Vector2 size, Vector3 location, Color color) { float x = 0, y = 0; if (size.X < 1f) { size.X = 1f; } if (size.Y < 1f) { size.Y = 1f; } _size = size; _location = location; List<VertexPositionColor> vertices = new List<VertexPositionColor>(); _faces = 0; for (y = -size.Y; y <= size.Y; y++) { vertices.Add(new VertexPositionColor(location + new Vector3(-size.X, y, 0), color)); vertices.Add(new VertexPositionColor(location + new Vector3(size.X, y, 0), color)); _faces++; } for (x = -size.X; x <= size.X; x++) { vertices.Add(new VertexPositionColor(location + new Vector3(x, -size.Y, 0), color)); vertices.Add(new VertexPositionColor(location + new Vector3(x, size.Y, 0), color)); _faces++; } _vertices = vertices.ToArray(); } public void Render(GraphicsDevice device) { device.DrawUserPrimitives<VertexPositionColor>(PrimitiveType.LineList, _vertices, 0, _faces); } } Like this: +----+----+----+----+ | | | | | +----+----+----+----+ | | | | | +----+----+----+----+ | | | | | +----+----+----+----+ | | | | | +----+----+----+----+ Anyone knows what I'm doing wrong? If I add a Shape without texture, it's set automatically to VertexColorEnabled and TextureEnabled = false. This is how I render it: foreach (RenderObject render in _renderObjects) { render.Effect.Projection = projection; render.Effect.View = view; render.Effect.World = world; foreach (EffectPass pass in render.Effect.CurrentTechnique.Passes) { pass.Apply(); try { // Could be a Grid2D render.Shape.Render(_device); } catch { throw; } } } Exception is thrown: The current vertex shader declaration does not include all the elements required by the current Vertex Shader. Normal0 is missing. Simply put, I can't figure out how to draw a few lines. I want to draw them one at a time and I guess that's the problem I haven't figured out, and even when I tried rendering vertices[i], vertices[i+1] and primitiveCount = 1, vertices = 2, and so on it didn't work either. Any suggestions?

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  • Camera doesn't move

    - by hugo
    Here is my code, as my subject indicates i have implemented a camera but I couldn't make it move. #define PI_OVER_180 0.0174532925f #define GL_CLAMP_TO_EDGE 0x812F #include "metinalifeyyaz.h" #include <GL/glu.h> #include <GL/glut.h> #include <QTimer> #include <cmath> #include <QKeyEvent> #include <QWidget> #include <QDebug> metinalifeyyaz::metinalifeyyaz(QWidget *parent) : QGLWidget(parent) { this->setFocusPolicy(Qt:: StrongFocus); time = QTime::currentTime(); timer = new QTimer(this); timer->setSingleShot(true); connect(timer, SIGNAL(timeout()), this, SLOT(updateGL())); xpos = yrot = zpos = 0; walkbias = walkbiasangle = lookupdown = 0.0f; keyUp = keyDown = keyLeft = keyRight = keyPageUp = keyPageDown = false; } void metinalifeyyaz::drawBall() { //glTranslatef(6,0,4); glutSolidSphere(0.10005,300,30); } metinalifeyyaz:: ~metinalifeyyaz(){ glDeleteTextures(1,texture); } void metinalifeyyaz::initializeGL(){ glShadeModel(GL_SMOOTH); glClearColor(1.0,1.0,1.0,0.5); glClearDepth(1.0f); glEnable(GL_DEPTH_TEST); glEnable(GL_TEXTURE_2D); glDepthFunc(GL_LEQUAL); glClearColor(1.0,1.0,1.0,1.0); glShadeModel(GL_SMOOTH); GLfloat mat_specular[]={1.0,1.0,1.0,1.0}; GLfloat mat_shininess []={30.0}; GLfloat light_position[]={1.0,1.0,1.0}; glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular); glMaterialfv(GL_FRONT,GL_SHININESS,mat_shininess); glLightfv(GL_LIGHT0, GL_POSITION, light_position); glEnable(GL_LIGHT0); glEnable(GL_LIGHTING); QImage img1 = convertToGLFormat(QImage(":/new/prefix1/halisaha2.bmp")); QImage img2 = convertToGLFormat(QImage(":/new/prefix1/white.bmp")); glGenTextures(2,texture); glBindTexture(GL_TEXTURE_2D, texture[0]); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, img1.width(), img1.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE, img1.bits()); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glBindTexture(GL_TEXTURE_2D, texture[1]); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, img2.width(), img2.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE, img2.bits()); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); // Really nice perspective calculations } void metinalifeyyaz::resizeGL(int w, int h){ if(h==0) h=1; glViewport(0,0,w,h); glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluPerspective(45.0f, static_cast<GLfloat>(w)/h,0.1f,100.0f); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); } void metinalifeyyaz::paintGL(){ movePlayer(); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glLoadIdentity(); GLfloat xtrans = -xpos; GLfloat ytrans = -walkbias - 0.50f; GLfloat ztrans = -zpos; GLfloat sceneroty = 360.0f - yrot; glLoadIdentity(); glRotatef(lookupdown, 1.0f, 0.0f, 0.0f); glRotatef(sceneroty, 0.0f, 1.0f, 0.0f); glTranslatef(xtrans, ytrans+50, ztrans-130); glLoadIdentity(); glTranslatef(1.0f,0.0f,-18.0f); glRotatef(45,1,0,0); drawScene(); int delay = time.msecsTo(QTime::currentTime()); if (delay == 0) delay = 1; time = QTime::currentTime(); timer->start(qMax(0,10 - delay)); } void metinalifeyyaz::movePlayer() { if (keyUp) { xpos -= sin(yrot * PI_OVER_180) * 0.5f; zpos -= cos(yrot * PI_OVER_180) * 0.5f; if (walkbiasangle >= 360.0f) walkbiasangle = 0.0f; else walkbiasangle += 7.0f; walkbias = sin(walkbiasangle * PI_OVER_180) / 10.0f; } else if (keyDown) { xpos += sin(yrot * PI_OVER_180)*0.5f; zpos += cos(yrot * PI_OVER_180)*0.5f ; if (walkbiasangle <= 7.0f) walkbiasangle = 360.0f; else walkbiasangle -= 7.0f; walkbias = sin(walkbiasangle * PI_OVER_180) / 10.0f; } if (keyLeft) yrot += 0.5f; else if (keyRight) yrot -= 0.5f; if (keyPageUp) lookupdown -= 0.5; else if (keyPageDown) lookupdown += 0.5; } void metinalifeyyaz::keyPressEvent(QKeyEvent *event) { switch (event->key()) { case Qt::Key_Escape: close(); break; case Qt::Key_F1: setWindowState(windowState() ^ Qt::WindowFullScreen); break; default: QGLWidget::keyPressEvent(event); case Qt::Key_PageUp: keyPageUp = true; break; case Qt::Key_PageDown: keyPageDown = true; break; case Qt::Key_Left: keyLeft = true; break; case Qt::Key_Right: keyRight = true; break; case Qt::Key_Up: keyUp = true; break; case Qt::Key_Down: keyDown = true; break; } } void metinalifeyyaz::changeEvent(QEvent *event) { switch (event->type()) { case QEvent::WindowStateChange: if (windowState() == Qt::WindowFullScreen) setCursor(Qt::BlankCursor); else unsetCursor(); break; default: break; } } void metinalifeyyaz::keyReleaseEvent(QKeyEvent *event) { switch (event->key()) { case Qt::Key_PageUp: keyPageUp = false; break; case Qt::Key_PageDown: keyPageDown = false; break; case Qt::Key_Left: keyLeft = false; break; case Qt::Key_Right: keyRight = false; break; case Qt::Key_Up: keyUp = false; break; case Qt::Key_Down: keyDown = false; break; default: QGLWidget::keyReleaseEvent(event); } } void metinalifeyyaz::drawScene(){ glBegin(GL_QUADS); glNormal3f(0.0f,0.0f,1.0f); // glColor3f(0,0,1); //back glVertex3f(-6,0,-4); glVertex3f(-6,-0.5,-4); glVertex3f(6,-0.5,-4); glVertex3f(6,0,-4); glEnd(); glBegin(GL_QUADS); glNormal3f(0.0f,0.0f,-1.0f); //front glVertex3f(6,0,4); glVertex3f(6,-0.5,4); glVertex3f(-6,-0.5,4); glVertex3f(-6,0,4); glEnd(); glBegin(GL_QUADS); glNormal3f(-1.0f,0.0f,0.0f); // glColor3f(0,0,1); //left glVertex3f(-6,0,4); glVertex3f(-6,-0.5,4); glVertex3f(-6,-0.5,-4); glVertex3f(-6,0,-4); glEnd(); glBegin(GL_QUADS); glNormal3f(1.0f,0.0f,0.0f); // glColor3f(0,0,1); //right glVertex3f(6,0,-4); glVertex3f(6,-0.5,-4); glVertex3f(6,-0.5,4); glVertex3f(6,0,4); glEnd(); glBindTexture(GL_TEXTURE_2D, texture[0]); glBegin(GL_QUADS); glNormal3f(0.0f,1.0f,0.0f);//top glTexCoord2f(1.0f,0.0f); glVertex3f(6,0,-4); glTexCoord2f(1.0f,1.0f); glVertex3f(6,0,4); glTexCoord2f(0.0f,1.0f); glVertex3f(-6,0,4); glTexCoord2f(0.0f,0.0f); glVertex3f(-6,0,-4); glEnd(); glBegin(GL_QUADS); glNormal3f(0.0f,-1.0f,0.0f); //glColor3f(0,0,1); //bottom glVertex3f(6,-0.5,-4); glVertex3f(6,-0.5,4); glVertex3f(-6,-0.5,4); glVertex3f(-6,-0.5,-4); glEnd(); // glPushMatrix(); glBindTexture(GL_TEXTURE_2D, texture[1]); glBegin(GL_QUADS); glNormal3f(1.0f,0.0f,0.0f); glTexCoord2f(1.0f,0.0f); //right far goal post front face glVertex3f(5,0.5,-0.95); glTexCoord2f(1.0f,1.0f); glVertex3f(5,0,-0.95); glTexCoord2f(0.0f,1.0f); glVertex3f(5,0,-1); glTexCoord2f(0.0f,0.0f); glVertex3f(5, 0.5, -1); glColor3f(1,1,1); //right far goal post back face glVertex3f(5.05,0.5,-0.95); glVertex3f(5.05,0,-0.95); glVertex3f(5.05,0,-1); glVertex3f(5.05, 0.5, -1); glColor3f(1,1,1); //right far goal post left face glVertex3f(5,0.5,-1); glVertex3f(5,0,-1); glVertex3f(5.05,0,-1); glVertex3f(5.05, 0.5, -1); glColor3f(1,1,1); //right far goal post right face glVertex3f(5.05,0.5,-0.95); glVertex3f(5.05,0,-0.95); glVertex3f(5,0,-0.95); glVertex3f(5, 0.5, -0.95); glColor3f(1,1,1); //right near goal post front face glVertex3f(5,0.5,0.95); glVertex3f(5,0,0.95); glVertex3f(5,0,1); glVertex3f(5,0.5, 1); glColor3f(1,1,1); //right near goal post back face glVertex3f(5.05,0.5,0.95); glVertex3f(5.05,0,0.95); glVertex3f(5.05,0,1); glVertex3f(5.05,0.5, 1); glColor3f(1,1,1); //right near goal post left face glVertex3f(5,0.5,1); glVertex3f(5,0,1); glVertex3f(5.05,0,1); glVertex3f(5.05,0.5, 1); glColor3f(1,1,1); //right near goal post right face glVertex3f(5.05,0.5,0.95); glVertex3f(5.05,0,0.95); glVertex3f(5,0,0.95); glVertex3f(5,0.5, 0.95); glColor3f(1,1,1); //right crossbar front face glVertex3f(5,0.55,-1); glVertex3f(5,0.55,1); glVertex3f(5,0.5,1); glVertex3f(5,0.5,-1); glColor3f(1,1,1); //right crossbar back face glVertex3f(5.05,0.55,-1); glVertex3f(5.05,0.55,1); glVertex3f(5.05,0.5,1); glVertex3f(5.05,0.5,-1); glColor3f(1,1,1); //right crossbar bottom face glVertex3f(5.05,0.5,-1); glVertex3f(5.05,0.5,1); glVertex3f(5,0.5,1); glVertex3f(5,0.5,-1); glColor3f(1,1,1); //right crossbar top face glVertex3f(5.05,0.55,-1); glVertex3f(5.05,0.55,1); glVertex3f(5,0.55,1); glVertex3f(5,0.55,-1); glColor3f(1,1,1); //left far goal post front face glVertex3f(-5,0.5,-0.95); glVertex3f(-5,0,-0.95); glVertex3f(-5,0,-1); glVertex3f(-5, 0.5, -1); glColor3f(1,1,1); //right far goal post back face glVertex3f(-5.05,0.5,-0.95); glVertex3f(-5.05,0,-0.95); glVertex3f(-5.05,0,-1); glVertex3f(-5.05, 0.5, -1); glColor3f(1,1,1); //right far goal post left face glVertex3f(-5,0.5,-1); glVertex3f(-5,0,-1); glVertex3f(-5.05,0,-1); glVertex3f(-5.05, 0.5, -1); glColor3f(1,1,1); //right far goal post right face glVertex3f(-5.05,0.5,-0.95); glVertex3f(-5.05,0,-0.95); glVertex3f(-5,0,-0.95); glVertex3f(-5, 0.5, -0.95); glColor3f(1,1,1); //left near goal post front face glVertex3f(-5,0.5,0.95); glVertex3f(-5,0,0.95); glVertex3f(-5,0,1); glVertex3f(-5,0.5, 1); glColor3f(1,1,1); //right near goal post back face glVertex3f(-5.05,0.5,0.95); glVertex3f(-5.05,0,0.95); glVertex3f(-5.05,0,1); glVertex3f(-5.05,0.5, 1); glColor3f(1,1,1); //right near goal post left face glVertex3f(-5,0.5,1); glVertex3f(-5,0,1); glVertex3f(-5.05,0,1); glVertex3f(-5.05,0.5, 1); glColor3f(1,1,1); //right near goal post right face glVertex3f(-5.05,0.5,0.95); glVertex3f(-5.05,0,0.95); glVertex3f(-5,0,0.95); glVertex3f(-5,0.5, 0.95); glColor3f(1,1,1); //left crossbar front face glVertex3f(-5,0.55,-1); glVertex3f(-5,0.55,1); glVertex3f(-5,0.5,1); glVertex3f(-5,0.5,-1); glColor3f(1,1,1); //right crossbar back face glVertex3f(-5.05,0.55,-1); glVertex3f(-5.05,0.55,1); glVertex3f(-5.05,0.5,1); glVertex3f(-5.05,0.5,-1); glColor3f(1,1,1); //right crossbar bottom face glVertex3f(-5.05,0.5,-1); glVertex3f(-5.05,0.5,1); glVertex3f(-5,0.5,1); glVertex3f(-5,0.5,-1); glColor3f(1,1,1); //right crossbar top face glVertex3f(-5.05,0.55,-1); glVertex3f(-5.05,0.55,1); glVertex3f(-5,0.55,1); glVertex3f(-5,0.55,-1); glEnd(); // glPopMatrix(); // glPushMatrix(); // glTranslatef(0,0,0); // glutSolidSphere(0.10005,500,30); // glPopMatrix(); }

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  • Character Jump Control

    - by Abdullah Sorathia
    I would like to know how can I control the jump movement of a character in Unity3D. Basically I am trying to program the jump in such a way that while a jump is in progress the character is allowed to move either left or right in mid-air when the corresponding keys are pressed. With my script the character will correctly move to the left when, for example, the left key is pressed, but when the right key is pressed afterwards, the character moves to the right before the movement to the left is completed. Following is the script: void Update () { if(touchingPlatform && Input.GetButtonDown("Jump")){ rigidbody.AddForce(jumpVelocity, ForceMode.VelocityChange); touchingPlatform = false; isJump=true; } //left & right movement Vector3 moveDir = Vector3.zero; if(Input.GetKey ("right")||Input.GetKey ("left")){ moveDir.x = Input.GetAxis("Horizontal"); // get result of AD keys in X if(ShipCurrentSpeed==0) { transform.position += moveDir * 3f * Time.deltaTime; }else if(ShipCurrentSpeed<=15) { transform.position += moveDir * ShipCurrentSpeed * 2f * Time.deltaTime; }else { transform.position += moveDir * 30f * Time.deltaTime; } }

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  • How to optimise mesh data

    - by Wardy
    So i have some procedurally generated mesh data and i want to reduce it down to its minimum number of verts. In case it matters this is a unity project. Working on the basis of a simple example, lets assume a typical flat surface of points 2 by 3. The point / vertex at [1,1] is used in many triangles. I've generated mesh for a voxel type engine that adds verts to a list based on face visiblility and now I want to remove all the duplicates. Can anyone come up with an efficient way of doing this because what i have is sooo bad its not even funny (and i don't even think it's logically correct) ... private void Optimize() { Vector3 v; Vector3 v2; for (int i = 0; i < Vertices.Count; i++) { v = Vertices[i]; for (int j = i+1; j < Vertices.Count; j++) { v2 = Vertices[j]; if (v.x == v2.x && v.y == v2.y && v.z == v2.z) { for (int ind = 0; ind < Indices.Count; ind++) { if (Indices[ind] == j) { Indices[ind] = i; } else if (Indices[ind] > j && Indices[ind] > 0) Indices[ind]--; } Vertices.RemoveAt(j); Uvs.RemoveAt(j); Normals.RemoveAt(j); } } } } EDIT: Ok i managed to get this (code sample above updated) to render an "optimised" set of verts but the UV data is all wrong now, which would make sense because i'm basically just removing any UV Vector that represents a UV coord for a removed vert and not actually considering what I need to do to "fix the tri" so to speak. The code now seemingly does work but its quite time consuming, still looking to further optimise.

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  • When mapping the surface of a sphere with tiles, how might you deal with polar distortion?

    - by clweeks
    It's easy to deal with the way locations interact on a clean Cartesian grid. It's just vanilla math. And you can kind of ignore the geometry of the sphere's surface for a bunch of it if you want to just truncate the poles or something. But I keep coming up with ideas for games where the polar space matters. Geo-coded ARGs and global roguelikes and stuff. I want square(ish?) locations -- reasonably representable by square tiles of the same size across the globe, anyway. This has to be a solved problem, right? What are the solutions? ETA: At the equator -- and assuming that your square locations are reasonably small, it's close enough to true that you can get away with having one square in the rows north and south of the most equatorial row. And you could probably get away with that by just hand-waving the difference up to like 45-degrees or so. But eventually, you need to have fewer squares in a pole-ward circumferential row. If I reduce the length of the row by one and offset the squares by 1/2 then they're just like hexes and it's relatively easy to do the coding to keep track of the connections. But as you get pole-ward, it gets more and more extreme. Projecting the surface of the world onto the surface of a cube is tempting. But I figured there must be more elegant solutions already in use. If I did the cube thing (not dissecting it further through geodesy) Are there any pros and cons related to placing the pole at the center of a face or at the vertex of three sides?

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