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• Fog shader camera problem

  - by MaT

  I have some difficulties with my vertex-fragment fog shader in Unity. I have a good visual result but the problem is that the gradient is based on the camera's position, it moves as the camera moves. I don't know how to fix it. Here is the shader code. struct v2f { float4 pos : SV_POSITION; float4 grabUV : TEXCOORD0; float2 uv_depth : TEXCOORD1; float4 interpolatedRay : TEXCOORD2; float4 screenPos : TEXCOORD3; }; v2f vert(appdata_base v) { v2f o; o.pos = mul(UNITY_MATRIX_MVP, v.vertex); o.uv_depth = v.texcoord.xy; o.grabUV = ComputeGrabScreenPos(o.pos); half index = v.vertex.z; o.screenPos = ComputeScreenPos(o.pos); o.interpolatedRay = mul(UNITY_MATRIX_MV, v.vertex); return o; } sampler2D _GrabTexture; float4 frag(v2f IN) : COLOR { float3 uv = UNITY_PROJ_COORD(IN.grabUV); float dpth = UNITY_SAMPLE_DEPTH(tex2Dproj(_CameraDepthTexture, uv)); dpth = LinearEyeDepth(dpth); float4 wsPos = (IN.screenPos + dpth * IN.interpolatedRay); // Here is the problem but how to fix it float fogVert = max(0.0, (wsPos.y - _Depth) * (_DepthScale * 0.1f)); fogVert *= fogVert; fogVert = (exp (-fogVert)); return fogVert; } Thanks a lot !

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• OpenGL ES Basic Fragment Shader help with transparency

  - by Chris

  I have just spent my first half hour playing with the shader language. I have modified the basic program I have which renders the texture, to allow me to colour the texture. varying vec2 texCoord; uniform sampler2D texSampler; /* Given the texture coordinates, our pixel shader grabs the corresponding * color from the texture. */ void main() { //gl_FragColor = texture2D(texSampler, texCoord); gl_FragColor = vec4(0,1,0,1)*vec4(texture2D(texSampler,texCoord).xyz,1); } I have noticed how this affects my transparent textures, and I believe I am loosing the alpha channel which would explain why previously transparent area's appear totally black. If I use the following line instead, I am shown the transparent area's gl_FragColor = vec4(0,1,0,1)*vec4(texture2D(texSampler,texCoord).aaa,1); How can I retain the transparency after this modification to the colour? I have seen various things about a .w property, and also luminous, but my tweaks with those and the .aaa property are not working XD

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• Rendering large and high poly meshes

  - by Aurus

  Consider an huge terrain that has a lot polygons, to render this terrain I thought of following techniques: Using height-map instead of raw meshes: Yes, but I want to create a lot of caves and stuff that simply wont work with height-maps. Using voxels: Yes, but I think that this would be to much since I don't even want to support changing terrain.. Split into multiple chunks and do some sort of LOD with the mesh: Yes, but how would I do that? Tessellation usually creates more detail not less. Precompute the same mesh in lower poly version (like Mudbox does) and depending on the distance it renders one of these meshes: Graphic memory is limited and uploading only the chunks won't solve that problem since the traffic would be too high. IMO the last one sounds really good, but imagine the following process: Upload and render the chunks depending on the current player position. [No problem] Player will walk straight forward Now we maybe have to change on of the low poly chunk with the high poly one So, Remove the low poly chunk and load the high poly chunk [Already to much traffic here, I think] I am not very experienced in graphic programming and maybe the upper process is totally okay but somehow I think it is too much. And how about the disk space it would require.. I think 3 kind of levels would be fine but isn't that also too much? (I am using OpenGL but I don't think that this is important)

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• How to bind std::map to Lua with LuaBind

  - by MahanGM

  Is this possible in lua to achieve? player.scripts["movement"].properties["stat"] = "stand" print (player.scripts["movement"].properties["stat"]) I've done getter method in c++ with this approach: luabind::object FakeScript::getProp() { luabind::object obj = luabind::newtable(L); for(auto i = this->properties.begin(); i != this->properties.end(); i++) { obj[i->first] = i->second; } return obj; } But I'm stuck with setter. The first line in lua code which I'm trying to set value "stand" for key "stat" is not going to work and it keep redirecting me to the getter method. Setter method only works when I drop ["stat"] from properties. I can do something like this for setter in my script: player.scripts["movement"].properties = {stat = "stand"} But this isn't what I want because I have to go through my real keys in c++ to determine which key is placed in setter argument table value. This is my map in class: std::map<std::string, std::string> properties;

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• What are the benefits of designing a KeyBinding relay?

  - by Adam Naylor

  The input system of Quake3 is handled using a Keybinding relay, whereby each keypress is matched against a 'binding' which is then passed to the CLI along with a time stamp of when the keypress (or release) occurred. I just wanted to get an idea from developers what they considered to be the key benefits of designing your input system around this approach? One thing i don't particularly like is the appending of the timestamp to the bound command. This seems like a bit of a hack to bend the CLI into handling the games input? Also I feel that detecting the keypress only to add the command to a stream of text that gets parsed at a later date to be a slightly latent way of responding to input? (or is this unfounded?) The only real benefit i can see is that it allows you to bind 'complex' commands to keypresses; like 'switch weapon;+fire;' for example. Or maybe for journaling purposes? Thanks for any insights!

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• Is it important for reflection-based serialization maintain consistent field ordering?

  - by Matchlighter

  I just finished writing a packet builder that dynamically loads data into a data stream for eventual network transmission. Each builder operates by finding fields in a given class (and its superclasses) that are marked with a @data annotation. When I finishing my implementation, I remembered that getFields() does not return results in any specific order. Should reflection-based methods for serializing arbitrary data (like my packets) attempt to preserve a specific field ordering (such as alphabetical), and if so, how?

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• My vertex shader doesn't affect texture coords or diffuse info but works for position

  - by tina nyaa

  I am new to 3D and DirectX - in the past I have only used abstractions for 2D drawing. Over the past month I've been studying really hard and I'm trying to modify and adapt some of the shaders as part of my personal 'study project'. Below I have a shader, modified from one of the Microsoft samples. I set diffuse and tex0 vertex shader outputs to zero, but my model still shows the full texture and lighting as if I hadn't changed the values from the vertex buffer. Changing the position of the model works, but nothing else. Why is this? // // Skinned Mesh Effect file // Copyright (c) 2000-2002 Microsoft Corporation. All rights reserved. // float4 lhtDir = {0.0f, 0.0f, -1.0f, 1.0f}; //light Direction float4 lightDiffuse = {0.6f, 0.6f, 0.6f, 1.0f}; // Light Diffuse float4 MaterialAmbient : MATERIALAMBIENT = {0.1f, 0.1f, 0.1f, 1.0f}; float4 MaterialDiffuse : MATERIALDIFFUSE = {0.8f, 0.8f, 0.8f, 1.0f}; // Matrix Pallette static const int MAX_MATRICES = 100; float4x3 mWorldMatrixArray[MAX_MATRICES] : WORLDMATRIXARRAY; float4x4 mViewProj : VIEWPROJECTION; /////////////////////////////////////////////////////// struct VS_INPUT { float4 Pos : POSITION; float4 BlendWeights : BLENDWEIGHT; float4 BlendIndices : BLENDINDICES; float3 Normal : NORMAL; float3 Tex0 : TEXCOORD0; }; struct VS_OUTPUT { float4 Pos : POSITION; float4 Diffuse : COLOR; float2 Tex0 : TEXCOORD0; }; float3 Diffuse(float3 Normal) { float CosTheta; // N.L Clamped CosTheta = max(0.0f, dot(Normal, lhtDir.xyz)); // propogate scalar result to vector return (CosTheta); } VS_OUTPUT VShade(VS_INPUT i, uniform int NumBones) { VS_OUTPUT o; float3 Pos = 0.0f; float3 Normal = 0.0f; float LastWeight = 0.0f; // Compensate for lack of UBYTE4 on Geforce3 int4 IndexVector = D3DCOLORtoUBYTE4(i.BlendIndices); // cast the vectors to arrays for use in the for loop below float BlendWeightsArray[4] = (float[4])i.BlendWeights; int IndexArray[4] = (int[4])IndexVector; // calculate the pos/normal using the "normal" weights // and accumulate the weights to calculate the last weight for (int iBone = 0; iBone < NumBones-1; iBone++) { LastWeight = LastWeight + BlendWeightsArray[iBone]; Pos += mul(i.Pos, mWorldMatrixArray[IndexArray[iBone]]) * BlendWeightsArray[iBone]; Normal += mul(i.Normal, mWorldMatrixArray[IndexArray[iBone]]) * BlendWeightsArray[iBone]; } LastWeight = 1.0f - LastWeight; // Now that we have the calculated weight, add in the final influence Pos += (mul(i.Pos, mWorldMatrixArray[IndexArray[NumBones-1]]) * LastWeight); Normal += (mul(i.Normal, mWorldMatrixArray[IndexArray[NumBones-1]]) * LastWeight); // transform position from world space into view and then projection space //o.Pos = mul(float4(Pos.xyz, 1.0f), mViewProj); o.Pos = mul(float4(Pos.xyz, 1.0f), mViewProj); o.Diffuse.x = 0.0f; o.Diffuse.y = 0.0f; o.Diffuse.z = 0.0f; o.Diffuse.w = 0.0f; o.Tex0 = float2(0,0); return o; } technique t0 { pass p0 { VertexShader = compile vs_3_0 VShade(4); } } I am currently using the SlimDX .NET wrapper around DirectX, but the API is extremely similar: public void Draw() { var device = vertexBuffer.Device; device.Clear(ClearFlags.Target | ClearFlags.ZBuffer, Color.White, 1.0f, 0); device.SetRenderState(RenderState.Lighting, true); device.SetRenderState(RenderState.DitherEnable, true); device.SetRenderState(RenderState.ZEnable, true); device.SetRenderState(RenderState.CullMode, Cull.Counterclockwise); device.SetRenderState(RenderState.NormalizeNormals, true); device.SetSamplerState(0, SamplerState.MagFilter, TextureFilter.Anisotropic); device.SetSamplerState(0, SamplerState.MinFilter, TextureFilter.Anisotropic); device.SetTransform(TransformState.World, Matrix.Identity * Matrix.Translation(0, -50, 0)); device.SetTransform(TransformState.View, Matrix.LookAtLH(new Vector3(-200, 0, 0), Vector3.Zero, Vector3.UnitY)); device.SetTransform(TransformState.Projection, Matrix.PerspectiveFovLH((float)Math.PI / 4, (float)device.Viewport.Width / device.Viewport.Height, 10, 10000000)); var material = new Material(); material.Ambient = material.Diffuse = material.Emissive = material.Specular = new Color4(Color.White); material.Power = 1f; device.SetStreamSource(0, vertexBuffer, 0, vertexSize); device.VertexDeclaration = vertexDeclaration; device.Indices = indexBuffer; device.Material = material; device.SetTexture(0, texture); var param = effect.GetParameter(null, "mWorldMatrixArray"); var boneWorldTransforms = bones.OrderedBones.OrderBy(x => x.Id).Select(x => x.CombinedTransformation).ToArray(); effect.SetValue(param, boneWorldTransforms); effect.SetValue(effect.GetParameter(null, "mViewProj"), Matrix.Identity);// Matrix.PerspectiveFovLH((float)Math.PI / 4, (float)device.Viewport.Width / device.Viewport.Height, 10, 10000000)); effect.SetValue(effect.GetParameter(null, "MaterialDiffuse"), material.Diffuse); effect.SetValue(effect.GetParameter(null, "MaterialAmbient"), material.Ambient); effect.Technique = effect.GetTechnique(0); var passes = effect.Begin(FX.DoNotSaveState); for (var i = 0; i < passes; i++) { effect.BeginPass(i); device.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, skin.Vertices.Length, 0, skin.Indicies.Length / 3); effect.EndPass(); } effect.End(); } Again, I set diffuse and tex0 vertex shader outputs to zero, but my model still shows the full texture and lighting as if I hadn't changed the values from the vertex buffer. Changing the position of the model works, but nothing else. Why is this? Also, whatever I set in the bone transformation matrices doesn't seem to have an effect on my model. If I set every bone transformation to a zero matrix, the model still shows up as if nothing had happened, but changing the Pos field in shader output makes the model disappear. I don't understand why I'm getting this kind of behaviour. Thank you!

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• How are these bullets done?

  - by Mike

  I really want to know how the bullets in Radiangames Inferno are done. The bullets seem like they are just billboard particles but I am curious about how their tails are implemented. They can curve so this means they are not just a billboard. Also, they appear continuous which implies that the tails are not made of a bunch of smaller particles (I think). Can anyone shead some light on this for me?

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• Can't click on a button with startDrag() active on stage

  - by Pedro

  I need to know how can I enable mouse click on a button when I have a MouseEvent listener for the stage. I have a MClip associated with the mouse cursor: Mouse.hide(); scope.startDrag(true); And an MouseEnvet on the stage: stage.addEventListener(MouseEvent.CLICK, FunctionXYZ); When I try to click on any button they don't assume the function that I create for those buttons... for example, button for fullscreen, exit, help, etc... Thank you very much. BR, Pedro

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• Xna Equivalent of Viewport.Unproject in a draw call as a matrix transformation

  - by Nick Crowther

  I am making a 2D sidescroller and I would like to draw my sprite to world space instead of client space so I do not have to lock it to the center of the screen and when the camera stops the sprite will walk off screen instead of being stuck at the center. In order to do this I wanted to make a transformation matrix that goes in my draw call. I have seen something like this: http://stackoverflow.com/questions/3570192/xna-viewport-projection-and-spritebatch I have seen Matrix.CreateOrthographic() used to go from Worldspace to client space but, how would I go about using it to go from clientspace to worldspace? I was going to try putting my returns from the viewport.unproject method I have into a scale matrix such as: blah = Matrix.CreateScale(unproject.X,unproject.Y,0); however, that doesn't seem to work correctly. Here is what I'm calling in my draw method(where X is the coordinate my camera should follow): Vector3 test = screentoworld(X, graphics); var clienttoworld = Matrix.CreateScale(test.X,test.Y, 0); animationPlayer.Draw(theSpriteBatch, new Vector2(X.X,X.Y),false,false,0,Color.White,new Vector2(1,1),clienttoworld); Here is my code in my unproject method: Vector3 screentoworld(Vector2 some, GraphicsDevice graphics): Vector2 Position =(some.X,some.Y); var project = Matrix.CreateOrthographic(5*graphicsdevice.Viewport.Width, graphicsdevice.Viewport.Height, 0, 1); var viewMatrix = Matrix.CreateLookAt( new Vector3(0, 0, -4.3f), new Vector3(X.X,X.Y,0), Vector3.Up); //I have also tried substituting (cam.Position.X,cam.Position.Y,0) in for the (0,0,-4.3f) Vector3 nearSource = new Vector3(Position, 0f); Vector3 nearPoint = graphicsdevice.Viewport.Unproject(nearSource, project, viewMatrix, Matrix.Identity); return nearPoint;

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• What is the best Broadphase Interface for moving spheres?

  - by Molmasepic

  As of now I am working on optimizing the performance of the physics and collision, and as of now I am having some slowdowns on my other computers from my main. I have well over 3000 btSphereShape Rigidbodies and 2/3 of them do not move at all, but I am noticing(by the profile below) that collision is taking a bit of time to maneuver. Each sample counts as 0.01 seconds. % cumulative self self total time seconds seconds calls ms/call ms/call name 10.09 0.65 0.65 SphereTriangleDetector::collide(btVector3 const&, btVector3&, btVector3&, float&, float&, float) 7.61 1.14 0.49 btSphereTriangleCollisionAlgorithm::processCollision(btCollisionObject*, btCollisionObject*, btDispatcherInfo const&, btManifoldResult*) 5.59 1.50 0.36 btConvexTriangleCallback::processTriangle(btVector3*, int, int) 5.43 1.85 0.35 btQuantizedBvh::reportAabbOverlappingNodex(btNodeOverlapCallback*, btVector3 const&, btVector3 const&) const 4.97 2.17 0.32 btBvhTriangleMeshShape::processAllTriangles(btTriangleCallback*, btVector3 const&, btVector3 const&) const::MyNodeOverlapCallback::processNode(int, int) 4.19 2.44 0.27 btSequentialImpulseConstraintSolver::resolveSingleConstraintRowGeneric(btRigidBody&, btRigidBody&, btSolverConstraint const&) 4.04 2.70 0.26 btSequentialImpulseConstraintSolver::resolveSingleConstraintRowLowerLimit(btRigidBody&, btRigidBody&, btSolverConstraint const&) 3.73 2.94 0.24 Ogre::OctreeSceneManager::walkOctree(Ogre::OctreeCamera*, Ogre::RenderQueue*, Ogre::Octree*, Ogre::VisibleObjectsBoundsInfo*, bool, bool) 3.42 3.16 0.22 btTriangleShape::getVertex(int, btVector3&) const 2.48 3.32 0.16 Ogre::Frustum::isVisible(Ogre::AxisAlignedBox const&, Ogre::FrustumPlane*) const 2.33 3.47 0.15 1246357 0.00 0.00 Gorilla::Layer::setVisible(bool) 2.33 3.62 0.15 SphereTriangleDetector::getClosestPoints(btDiscreteCollisionDetectorInterface::ClosestPointInput const&, btDiscreteCollisionDetectorInterface::Result&, btIDebugDraw*, bool) 1.86 3.74 0.12 btCollisionDispatcher::findAlgorithm(btCollisionObject*, btCollisionObject*, btPersistentManifold*) 1.86 3.86 0.12 btSequentialImpulseConstraintSolver::setupContactConstraint(btSolverConstraint&, btCollisionObject*, btCollisionObject*, btManifoldPoint&, btContactSolverInfo const&, btVector3&, float&, float&, btVector3&, btVector3&) 1.71 3.97 0.11 btTriangleShape::getEdge(int, btVector3&, btVector3&) const 1.55 4.07 0.10 _Unwind_SjLj_Register 1.55 4.17 0.10 _Unwind_SjLj_Unregister 1.55 4.27 0.10 Ogre::D3D9HardwareVertexBuffer::updateBufferResources(char const*, Ogre::D3D9HardwareVertexBuffer::BufferResources*) 1.40 4.36 0.09 btManifoldResult::addContactPoint(btVector3 const&, btVector3 const&, float) 1.40 4.45 0.09 btSequentialImpulseConstraintSolver::setupFrictionConstraint(btSolverConstraint&, btVector3 const&, btRigidBody*, btRigidBody*, btManifoldPoint&, btVector3 const&, btVector3 const&, btCollisionObject*, btCollisionObject*, float, float, float) 1.24 4.53 0.08 btSequentialImpulseConstraintSolver::convertContact(btPersistentManifold*, btContactSolverInfo const&) 1.09 4.60 0.07 408760 0.00 0.00 Living::MapHide() 1.09 4.67 0.07 btSphereTriangleCollisionAlgorithm::~btSphereTriangleCollisionAlgorithm() 1.09 4.74 0.07 inflate_fast EDIT: Updated to show current Profile. I have only listed the functions using over 1% time from the many functions that are being used. Another thing is that each monster has a certain area that they stay in and are only active when a player is in said area. I was wondering if maybe there is a way to deactivate the non-active monsters from bullet(reactivating once in the area again) or maybe theres a different broadphase interface that I should use. The current BPI is btDbvtBroadphase. EDIT: Here is the Profile on the other computer(the top one is my main) Each sample counts as 0.01 seconds. % cumulative self self total time seconds seconds calls ms/call ms/call name 12.18 1.19 1.19 SphereTriangleDetector::collide(btVector3 const&, btVector3&, btVector3&, float&, float&, float) 6.76 1.85 0.66 btSphereTriangleCollisionAlgorithm::processCollision(btCollisionObject*, btCollisionObject*, btDispatcherInfo const&, btManifoldResult*) 5.83 2.42 0.57 btQuantizedBvh::reportAabbOverlappingNodex(btNodeOverlapCallback*, btVector3 const&, btVector3 const&) const 5.12 2.92 0.50 btConvexTriangleCallback::processTriangle(btVector3*, int, int) 4.61 3.37 0.45 btTriangleShape::getVertex(int, btVector3&) const 4.09 3.77 0.40 _Unwind_SjLj_Register 3.48 4.11 0.34 btBvhTriangleMeshShape::processAllTriangles(btTriangleCallback*, btVector3 const&, btVector3 const&) const::MyNodeOverlapCallback::processNode(int, int) 2.46 4.35 0.24 btSequentialImpulseConstraintSolver::resolveSingleConstraintRowLowerLimit(btRigidBody&, btRigidBody&, btSolverConstraint const&) 2.15 4.56 0.21 _Unwind_SjLj_Unregister 2.15 4.77 0.21 SphereTriangleDetector::getClosestPoints(btDiscreteCollisionDetectorInterface::ClosestPointInput const&, btDiscreteCollisionDetectorInterface::Result&, btIDebugDraw*, bool) 1.84 4.95 0.18 btTriangleShape::getEdge(int, btVector3&, btVector3&) const 1.64 5.11 0.16 btSequentialImpulseConstraintSolver::resolveSingleConstraintRowGeneric(btRigidBody&, btRigidBody&, btSolverConstraint const&) 1.54 5.26 0.15 btSequentialImpulseConstraintSolver::setupContactConstraint(btSolverConstraint&, btCollisionObject*, btCollisionObject*, btManifoldPoint&, btContactSolverInfo const&, btVector3&, float&, float&, btVector3&, btVector3&) 1.43 5.40 0.14 Ogre::D3D9HardwareVertexBuffer::updateBufferResources(char const*, Ogre::D3D9HardwareVertexBuffer::BufferResources*) 1.33 5.53 0.13 btManifoldResult::addContactPoint(btVector3 const&, btVector3 const&, float) 1.13 5.64 0.11 btRigidBody::predictIntegratedTransform(float, btTransform&) 1.13 5.75 0.11 btTriangleIndexVertexArray::getLockedReadOnlyVertexIndexBase(unsigned char const**, int&, PHY_ScalarType&, int&, unsigned char const**, int&, int&, PHY_ScalarType&, int) const 1.02 5.85 0.10 btSphereTriangleCollisionAlgorithm::CreateFunc::CreateCollisionAlgorithm(btCollisionAlgorithmConstructionInfo&, btCollisionObject*, btCollisionObject*) 1.02 5.95 0.10 btSphereTriangleCollisionAlgorithm::btSphereTriangleCollisionAlgorithm(btPersistentManifold*, btCollisionAlgorithmConstructionInfo const&, btCollisionObject*, btCollisionObject*, bool) Edited same as other Profile.

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• Custom Music in Skyrim's Creation Kit?

  - by CptSupermrkt

  Can you bring in external music such as mp3s? If so, how? I didn't see anything about this in the wiki Bethesda released. Also how does this work with regards to the Steam Workshop? Don't imagine they would appreciate uploading copyrighted content. I don't particularly care about making a public mod, I just want to screw around privately and create dungeons/towns using music from some of my favorite games. Thanks.

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• What exactly is UV and UVW Mapping?

  - by Michael Stum

  Trying to understand some basic 3D concepts, at the moment I'm trying to figure out how textures actually work. I know that UV and UVW mapping are techniques that map 2D Textures to 3D Objects - Wikipedia told me as much. I googled for explanations but only found tutorials that assumed that I already know what it is. From my understanding, each 3D Model is made out of Points, and several points create a face? Does each point or face have a secondary coordinate that maps to a x/y position in the 2D Texture? Or how does unwrapping manipulate the model? Also, what does the W in UVW really do, what does it offer over UV? As I understand it, W maps to the Z coordinate, but in what situation would I have different textures for the same X/Y and different Z, wouldn't the Z part be invisible? Or am I completely misunderstanding this?

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• What are the most common AI systems implemented in Tower Defense Games

  - by the_Dan

  I'm currently in the middle of researching on the various types of AI techniques used in tower defense type games. If someone could be help me in understanding the different types of techniques and their associated advantages. Using Google I already found several techniques. Random Map traversal Path finding e.g. Cost based Traversing Algorithms i.e. A* I have already found a great answer to this type of question with the below link, but I feel that this answer is tailored to FPS. If anyone could add to this and make it specific to tower defense games then I would be truly great-full. How is AI most commonly implemented in popular games? Example of such games would be: Radiant Defense Plant Vs Zombies - Not truly Intelligent, but there must be an AI system used right? Field Runners Edit: After further research I found an interesting book that may be useful: http://www.amazon.com/dp/0123747317/?tag=stackoverfl08-20

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• Quaternion dfference + time --> angular velocity (gyroscope in physics library)

  - by AndrewK

  I am using Bullet Physic library to program some function, where I have difference between orientation from gyroscope given in quaternion and orientation of my object, and time between each frame in milisecond. All I want is set the orientation from my gyroscope to orientation of my object in 3D space. But all I can do is set angular velocity to my object. I have orientation difference and time, and from that I calculate vector of angular velocity [Wx,Wy,Wz] from that formula: W(t) = 2 * dq(t)/dt * conj(q(t)) My code is: btQuaternion diffQuater = gyroQuater - boxQuater; btQuaternion conjBoxQuater = gyroQuater.inverse(); btQuaternion velQuater = ((diffQuater * 2.0f) / d_time) * conjBoxQuater; And everything works well, till I get: 1 rotating around Y axis, angle about 60 degrees, then I have these values in 2 critical frames: x: -0.013220 y: -0.038050 z: -0.021979 w: -0.074250 - diffQuater x: 0.120094 y: 0.818967 z: 0.156797 w: -0.538782 - gyroQuater x: 0.133313 y: 0.857016 z: 0.178776 w: -0.464531 - boxQuater x: 0.207781 y: 0.290452 z: 0.245594 - diffQuater -> euler angles x: 3.153619 y: -66.947929 z: 175.936615 - gyroQuater -> euler angles x: 4.290697 y: -57.553043 z: 173.320053 - boxQuater -> euler angles x: 0.138128 y: 2.823307 z: 1.025552 w: 0.131360 - velQuater d_time: 0.058000 x: 0.211020 y: 1.595124 z: 0.303650 w: -1.143846 - diffQuater x: 0.089518 y: 0.771939 z: 0.144527 w: -0.612543 - gyroQuater x: -0.121502 y: -0.823185 z: -0.159123 w: 0.531303 - boxQuater x: nan y: nan z: nan - diffQuater -> euler angles x: 2.985240 y: -76.304405 z: -170.555054 - gyroQuater -> euler angles x: 3.269681 y: -65.977966 z: 175.639420 - boxQuater -> euler angles x: -0.730262 y: -2.882153 z: -1.294721 w: 63.325996 - velQuater d_time: 0.063000 2 rotating around X axis, angle about 120 degrees, then I have these values in 2 critical frames: x: -0.013045 y: -0.004186 z: -0.005667 w: -0.022482 - diffQuater x: -0.848030 y: -0.187985 z: 0.114400 w: 0.482099 - gyroQuater x: -0.834985 y: -0.183799 z: 0.120067 w: 0.504580 - boxQuater x: 0.036336 y: 0.002312 z: 0.020859 - diffQuater -> euler angles x: -113.129463 y: 0.731925 z: 25.415056 - gyroQuater -> euler angles x: -110.232368 y: 0.860897 z: 25.350458 - boxQuater -> euler angles x: -0.865820 y: -0.456086 z: 0.034084 w: 0.013184 - velQuater d_time: 0.055000 x: -1.721662 y: -0.387898 z: 0.229844 w: 0.910235 - diffQuater x: -0.874310 y: -0.200132 z: 0.115142 w: 0.426933 - gyroQuater x: 0.847352 y: 0.187766 z: -0.114703 w: -0.483302 - boxQuater x: -144.402298 y: 4.891629 z: 71.309158 - diffQuater -> euler angles x: -119.515343 y: 1.745076 z: 26.646086 - gyroQuater -> euler angles x: -112.974533 y: 0.738675 z: 25.411509 - boxQuater -> euler angles x: 2.086195 y: 0.676526 z: -0.424351 w: 70.104248 - velQuater d_time: 0.057000 2 rotating around Z axis, angle about 120 degrees, then I have these values in 2 critical frames: x: -0.000736 y: 0.002812 z: -0.004692 w: -0.008181 - diffQuater x: -0.003829 y: 0.012045 z: -0.868035 w: 0.496343 - gyroQuater x: -0.003093 y: 0.009232 z: -0.863343 w: 0.504524 - boxQuater x: -0.000822 y: -0.003032 z: 0.004162 - diffQuater -> euler angles x: -1.415189 y: 0.304210 z: -120.481873 - gyroQuater -> euler angles x: -1.091881 y: 0.227784 z: -119.399445 - boxQuater -> euler angles x: 0.159042 y: 0.169228 z: -0.754599 w: 0.003900 - velQuater d_time: 0.025000 x: -0.007598 y: 0.024074 z: -1.749412 w: 0.968588 - diffQuater x: -0.003769 y: 0.012030 z: -0.881377 w: 0.472245 - gyroQuater x: 0.003829 y: -0.012045 z: 0.868035 w: -0.496343 - boxQuater x: -5.645197 y: 1.148993 z: -146.507187 - diffQuater -> euler angles x: -1.418294 y: 0.270319 z: -123.638245 - gyroQuater -> euler angles x: -1.415183 y: 0.304208 z: -120.481873 - boxQuater -> euler angles x: 0.017498 y: -0.013332 z: 2.040073 w: 148.120056 - velQuater d_time: 0.027000 The problem is the most visible in diffQuater - euler angles vector. Can someone tell me why it is like that? and how to solve that problem? All suggestions are welcome.

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• Corona SDK: Animation takes a long time to play after "prepare" step

  - by Michael Taufen

  First off, I'm using the current publicly available build, version 2011.704 I'm building a platformer, and have a character that runs along and jumps when the screen is tapped. While jumping, the animation code has him assume a svelte jumping pose, and upon the detection of a collision with the ground, he returns to running. All of this happens. The problem is that there is this strange gap of time, about 1/2 a second by the feel of it, where my character sits on the first frame of the run animation after landing, before it actually starts playing. This leads me to believe that the problem is somewhere between the "prepare" step of loading up a sprite set's animation sequence and the "play" step. Thanks in advance for any help :). My code for when my character lands is as follows: local function collisionHandler ( event ) if (event.object1.myName == "character") and (event.object2.type == "terrain") then inAir = false characterInstance:prepare( "run" ) -- TODO: time between prepare and play is curiously long... characterInstance:play() end end

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• LWJGL Determining whether or not a polygon is on-screen.

  - by Brandon oubiub

  Not sure whether this is an LWJGL or math question. I want to check whether a shape is on-screen, so that I don't have to render it if it isn't. First of all, is there any simple way to do this that I am overlooking? Like some method or something that I haven't found? I'm going to assume there isn't. I tried using my trigonometry skills, but it is hard to do this because of how glRotate also distorts the image a little for perspective and realism. Or, is there any way to easily determine if a ray starting from the camera, and going outward in a straight line intersects a shape? (I can probably do it with my math skillz, but is there an easier way?) By the way, I can easily determine the angle at which the camera is facing around the x and y axis. EDIT: Or, possibly, I could get the angles of a vector from the camera to the object, and compare those angles to my camera angles. But I have a feeling that the distorts from glRotate and glTranslate would be an issue. I'll try it though.

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• Effective way to check if an Entity/Player enters a region/trigger

  - by Chris

  I was wondering how multiplayer games detect if you enter a special region. Let's assume there is a huge map that is so big that simply checking it would become a huge performance issue. I've seen bukkit (a modding API for Minecraft servers) firing an Event on every single move. I don't think that larger games do the same because even if you have only a few coordinates you are interested in, you have to loop through a few trigger zone to see if the player is inside your region - for every player. This seems like an extremely CPU-intense operation to me even though I've never developed something like that. Is there a special algorithm that is used by larger games to accomplish this? The only thing I could imagine is to split up the world into multiple parts and to register the event not on the movement itself but on all the parts that are covered by your area and only check for areas that are registered in the current part. And another thing I would like to know: How could you detect when someone must have entered a trigger but you never saw him directly in it since his client only sent you an move packet shortly before entering and after leaving the trigger area. Drawing a line and calculate all colliding parts seems rather CPU intensive if you have to perform it every time.

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• Setting up collision using a tilemap and cocos2d

  - by James

  I'm building my first platformer using cocos2d and a tilemap. I'm having trouble coming up with a decent way of determining if the character is colliding with an object. More specifically, in which direction is the character colliding with an object. Following the tutorial here, I have made a separate "meta" layer of collidable tiles. The problem is that unless the character is in the tile, you can't detect the collision. Also, there's no way of telling WHERE the collision is occurring. The best solution would be one that could tell me if a character is up against a wall, or walking on top of a platform. However, I can't seem to figure out a good technique for this.

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• Pathfinding and BSP with Box2D

  - by Amplify91

  I'm looking into implementing AI in my 2D side-scrolling platformer, and I'm looking into using algorithms such as A*. For many kinds of pathfinding, we need some sort of grid or systems of nodes or polygon areas. My problem is that I am using Box2d for physics and I am not sure how best to create a structure that my AI can use besides placing individual nodes manually (something I really want to avoid) and using some sort of steering behavior. My level design is tile-based with each tile being about half of the height/width of my main character. The tiles are not all square (some are sloped). I'd like to have a system that can see what the terrain looks like for pathfinding and also keep track of the positions of other actors such as enemies. I'd like to avoid directly placing any nodes into my level design except for possible endpoints or goals. This question is related: How do you do AI path following within a 2d physics engine like farseer/box2d?, but it doesn't specify what kind of structure I could use instead of a list of nodes. I'm looking for some kind of grid or type of BSP that I can query for algorithms like A*.

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• First Person Camera strafing at angle

  - by Linkandzelda

  I have a simple camera class working in directx 11 allowing moving forward and rotating left and right. I'm trying to implement strafing into it but having some problems. The strafing works when there's no camera rotation, so when the camera starts at 0, 0, 0. But after rotating the camera in either direction it seems to strafe at an angle or inverted or just some odd stuff. Here is a video uploaded to Dropbox showing this behavior. https://dl.dropboxusercontent.com/u/2873587/IncorrectStrafing.mp4 And here is my camera class. I have a hunch that it's related to the calculation for camera position. I tried various different calculations in strafe and they all seem to follow the same pattern and same behavior. Also the m_camera_rotation represents the Y rotation, as pitching isn't implemented yet. #include "camera.h" camera::camera(float x, float y, float z, float initial_rotation) { m_x = x; m_y = y; m_z = z; m_camera_rotation = initial_rotation; updateDXZ(); } camera::~camera(void) { } void camera::updateDXZ() { m_dx = sin(m_camera_rotation * (XM_PI/180.0)); m_dz = cos(m_camera_rotation * (XM_PI/180.0)); } void camera::Rotate(float amount) { m_camera_rotation += amount; updateDXZ(); } void camera::Forward(float step) { m_x += step * m_dx; m_z += step * m_dz; } void camera::strafe(float amount) { float yaw = (XM_PI/180.0) * m_camera_rotation; m_x += cosf( yaw ) * amount; m_z += sinf( yaw ) * amount; } XMMATRIX camera::getViewMatrix() { updatePosition(); return XMMatrixLookAtLH(m_position, m_lookat, m_up); } void camera::updatePosition() { m_position = XMVectorSet(m_x, m_y, m_z, 0.0); m_lookat = XMVectorSet(m_x + m_dx, m_y, m_z + m_dz, 0.0); m_up = XMVectorSet(0.0, 1.0, 0.0, 0.0); }

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• How can I pass an array of floats to the fragment shader using textures?

  - by James

  I want to map out a 2D array of depth elements for the fragment shader to use to check depth against to create shadows. I want to be able to copy a float array into the GPU, but using large uniform arrays causes segfaults in openGL so that is not an option. I tried texturing but the best i got was to use GL_DEPTH_COMPONENT glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, 512, 512, 0, GL_DEPTH_COMPONENT, GL_FLOAT, smap); Which doesn't work because that stores depth components (0.0 - 1.0) which I don't want because I have no idea how to calculate them using the depth value produced by the light sources MVP matrix multiplied by the coordinate of each vertex. Is there any way to store and access large 2D arrays of floats in openGL?

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• Dynamic Environment Creation

  - by Jack

  I was wondering, I'm thinking on a more small-scale, abstracted level, but how does one create a dynamic environment a la Minecraft? In specific, I'm thinking of the world as a 3 dimensional array of block objects, how is it made so that large features such as oceans are created? The language isn't important, I'm thinking on a conceptual level, but if it helps, I use C# or C++. Thanks for any help!

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• obj-c classes and sub classes (Cocos2d) conversion

  - by Lewis

  Hi I'm using this version of cocos2d: https://github.com/krzysztofzablocki/CCNode-SFGestureRecognizers Which supports the UIGestureRecognizer within a CCLayer in a cocos2d scene like so: @interface HelloWorldLayer : CCLayer <UIGestureRecognizerDelegate> { } Now I want to make this custom gesture work within the scene, attaching it to a sprite in cocos2d: #import <Foundation/Foundation.h> #import <UIKit/UIGestureRecognizerSubclass.h> @protocol OneFingerRotationGestureRecognizerDelegate <NSObject> @optional - (void) rotation: (CGFloat) angle; - (void) finalAngle: (CGFloat) angle; @end @interface OneFingerRotationGestureRecognizer : UIGestureRecognizer { CGPoint midPoint; CGFloat innerRadius; CGFloat outerRadius; CGFloat cumulatedAngle; id <OneFingerRotationGestureRecognizerDelegate> target; } - (id) initWithMidPoint: (CGPoint) midPoint innerRadius: (CGFloat) innerRadius outerRadius: (CGFloat) outerRadius target: (id) target; - (void)reset; - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event; - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event; - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event; - (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event; @end #include <math.h> #import "OneFingerRotationGestureRecognizer.h" @implementation OneFingerRotationGestureRecognizer // private helper functions CGFloat distanceBetweenPoints(CGPoint point1, CGPoint point2); CGFloat angleBetweenLinesInDegrees(CGPoint beginLineA, CGPoint endLineA, CGPoint beginLineB, CGPoint endLineB); - (id) initWithMidPoint: (CGPoint) _midPoint innerRadius: (CGFloat) _innerRadius outerRadius: (CGFloat) _outerRadius target: (id <OneFingerRotationGestureRecognizerDelegate>) _target { if ((self = [super initWithTarget: _target action: nil])) { midPoint = _midPoint; innerRadius = _innerRadius; outerRadius = _outerRadius; target = _target; } return self; } /** Calculates the distance between point1 and point 2. */ CGFloat distanceBetweenPoints(CGPoint point1, CGPoint point2) { CGFloat dx = point1.x - point2.x; CGFloat dy = point1.y - point2.y; return sqrt(dx*dx + dy*dy); } CGFloat angleBetweenLinesInDegrees(CGPoint beginLineA, CGPoint endLineA, CGPoint beginLineB, CGPoint endLineB) { CGFloat a = endLineA.x - beginLineA.x; CGFloat b = endLineA.y - beginLineA.y; CGFloat c = endLineB.x - beginLineB.x; CGFloat d = endLineB.y - beginLineB.y; CGFloat atanA = atan2(a, b); CGFloat atanB = atan2(c, d); // convert radiants to degrees return (atanA - atanB) * 180 / M_PI; } #pragma mark - UIGestureRecognizer implementation - (void)reset { [super reset]; cumulatedAngle = 0; } - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { [super touchesBegan:touches withEvent:event]; if ([touches count] != 1) { self.state = UIGestureRecognizerStateFailed; return; } } - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { [super touchesMoved:touches withEvent:event]; if (self.state == UIGestureRecognizerStateFailed) return; CGPoint nowPoint = [[touches anyObject] locationInView: self.view]; CGPoint prevPoint = [[touches anyObject] previousLocationInView: self.view]; // make sure the new point is within the area CGFloat distance = distanceBetweenPoints(midPoint, nowPoint); if ( innerRadius <= distance && distance <= outerRadius) { // calculate rotation angle between two points CGFloat angle = angleBetweenLinesInDegrees(midPoint, prevPoint, midPoint, nowPoint); // fix value, if the 12 o'clock position is between prevPoint and nowPoint if (angle > 180) { angle -= 360; } else if (angle < -180) { angle += 360; } // sum up single steps cumulatedAngle += angle; // call delegate if ([target respondsToSelector: @selector(rotation:)]) { [target rotation:angle]; } } else { // finger moved outside the area self.state = UIGestureRecognizerStateFailed; } } - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event { [super touchesEnded:touches withEvent:event]; if (self.state == UIGestureRecognizerStatePossible) { self.state = UIGestureRecognizerStateRecognized; if ([target respondsToSelector: @selector(finalAngle:)]) { [target finalAngle:cumulatedAngle]; } } else { self.state = UIGestureRecognizerStateFailed; } cumulatedAngle = 0; } - (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event { [super touchesCancelled:touches withEvent:event]; self.state = UIGestureRecognizerStateFailed; cumulatedAngle = 0; } @end Header file for view controller: #import "OneFingerRotationGestureRecognizer.h" @interface OneFingerRotationGestureViewController : UIViewController <OneFingerRotationGestureRecognizerDelegate> @property (nonatomic, strong) IBOutlet UIImageView *image; @property (nonatomic, strong) IBOutlet UITextField *textDisplay; @end then this is in the .m file: gestureRecognizer = [[OneFingerRotationGestureRecognizer alloc] initWithMidPoint: midPoint innerRadius: outRadius / 3 outerRadius: outRadius target: self]; [self.view addGestureRecognizer: gestureRecognizer]; Now my question is, is it possible to add this custom gesture into the cocos2d project found on that github, and if so, what do I need to change in the OneFingerRotationGestureRecognizerDelegate to get it to work within cocos2d. Because at the minute it is setup in a standard iOS project and not a cocos2d project and I do not know enough about UIViews and classing/ sub classing in obj-c to get this to work. Also it seems to inherit from a UIView where cocos2d uses CCLayer. Kind regards, Lewis. I also realise I may have not included enough code from the custom gesture project for readers to interpret it fully, so the full project can be found here: https://github.com/melle/OneFingerRotationGestureDemo

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• Why aren't tangent space normal maps completely blue?

  - by seahorse

  Why aren't normal maps just blue? I would think that normal maps should be predominantly blue in color because the Z component of the normal is represented by blue. Normals point out of the surface in the Z direction so we should see blue as the predominant colour since the Z component is dominant. By definition tangent space is perpendicular to the surface. At any point we should have the normal always pointing in the Z (blue direction) with no X (red direction) or Y (green direction). Thus the normal map (since it is a "normal map") should have the colour of the normals which is just blue (R = x = 0, G = y = 0, B = z = 1) with no shades in between. But normal maps are not so, and they have gradients of shades in them. Why is this so?

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