• Advertisement

Education I wrote a Physics Engine and Articles for Beginners

Recommended Posts

I wrote a 3D Physics Engine in C++ that uses GJK, EPA, and a Sequential Constraint Solver. I wrote it with two goals in mind:

  1. Stacking blocks - it's stable at around 200, and a lot of fun to watch when they all fall down
  2. Education - I wanted to create a Physics Engine I could write about to help other people learn.

Point #2 is why I'm sharing today. I've written 11 posts that aim to teach the Physics Engine. I start from the beginning, Points and Vectors in 3D, and move up to the GJK algorithm for collision detection. There's a lot more I could cover, but I thought I'd share what I have so far to see if anyone is interested. 

The engine itself is on github: https://github.com/SaintDubious/DubiousEngine
And the articles are on my website: http://dubiousoft.com/2017/01/23/dubious-engine-table-of-contents/

If anyone is interested in learning how to make a Physics Engine, I hope you'll find this useful. I'd greatly appreciate feedback, discussion, questions, corrections, etc.


Share this post

Link to post
Share on other sites

Cloned the repo, had trouble building in 64bit, couldn't find your Utils.h include. Tried 32 bit and couldn't find SDL. Maybe you could try including the SDL headers into your project so people can just download and build without tinkering?

Share this post

Link to post
Share on other sites

Thank you for this. I'm not in need of one now (I'm working on 2D games atm and, coincidentally, using ^^^ that guy's ^^^ 2D collision library), but I've bookmarked it for when I move to 3D in the future.

I had a glance through some of the articles you wrote, and they seemed very clear and straightforward.

Share this post

Link to post
Share on other sites
On 10/6/2017 at 12:35 AM, Randy Gaul said:

Cloned the repo, had trouble building in 64bit, couldn't find your Utils.h include. Tried 32 bit and couldn't find SDL. Maybe you could try including the SDL headers into your project so people can just download and build without tinkering?

Thanks for the feedback, I really appreciate every extra set of eyes. You're right, the build is a mess, I haven't looked at it in ages. I've created an issue for myself to clean it up. I'm not sure if I'm allowed to include SDL within my own github repo, but I can certainly provide some clear build instructions so no one else has to flail.

Edit: I've finished with the cleanup. Now the 64 bit stuff seems to work as well. I hope everything has been sanitized. Unfortunately it's still a bit tough to figure out how to get OpenCL for your graphics card, I'm not sure how I can clean that bit up, but the SDL stuff it simpler.

Thank you.

Edited by alwekyerp

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Advertisement
  • Advertisement
  • Popular Tags

  • Advertisement
  • Popular Now

  • Similar Content

    • By MHG OstryTM
      Hello guys,
      I've released my game for the first time. I'm very excited about it and I hope you'll enjoy the game - Beer Ranger. It's a retro-like puzzle-platfromer which makes you think a lot or die trying. You have a squad of skilled dwarfs with special powers and your goal is tasty beer. There is a lot of traps as well as many solutions how to endure them - it is up to your choice how to complete the level! 
      Link to the project: Project site
      Link to the Steam site with video: Beer Ranger
      Have fun and please write feedback if you feel up to.
      Some screens: 

    • By francoisdiy
      So I wrote a programming language called C-Lesh to program games for my game maker Platformisis. It is a scripting language which tiles into the JavaScript game engine via a memory mapper using memory mapped I/O. Currently, I am porting the language as a standalone interpreter to be able to run on the PC and possibly other devices excluding the phone. The interpreter is being written in C++ so for those of you who are C++ fans you can see the different components implemented. Some background of the language and how to program in C-Lesh can be found here:

      As I program this thing I will post code from different components and explain.
    • By isu diss
      I'm trying to duplicate vertices using std::map to be used in a vertex buffer. I don't get the correct index buffer(myInds) or vertex buffer(myVerts). I can get the index array from FBX but it differs from what I get in the following std::map code. Any help is much appreciated.
      struct FBXVTX { XMFLOAT3 Position; XMFLOAT2 TextureCoord; XMFLOAT3 Normal; }; std::map< FBXVTX, int > myVertsMap; std::vector<FBXVTX> myVerts; std::vector<int> myInds; HRESULT FBXLoader::Open(HWND hWnd, char* Filename, bool UsePositionOnly) { HRESULT hr = S_OK; if (FBXM) { FBXIOS = FbxIOSettings::Create(FBXM, IOSROOT); FBXM->SetIOSettings(FBXIOS); FBXI = FbxImporter::Create(FBXM, ""); if (!(FBXI->Initialize(Filename, -1, FBXIOS))) { hr = E_FAIL; MessageBox(hWnd, (wchar_t*)FBXI->GetStatus().GetErrorString(), TEXT("ALM"), MB_OK); } FBXS = FbxScene::Create(FBXM, "REALMS"); if (!FBXS) { hr = E_FAIL; MessageBox(hWnd, TEXT("Failed to create the scene"), TEXT("ALM"), MB_OK); } if (!(FBXI->Import(FBXS))) { hr = E_FAIL; MessageBox(hWnd, TEXT("Failed to import fbx file content into the scene"), TEXT("ALM"), MB_OK); } FbxAxisSystem OurAxisSystem = FbxAxisSystem::DirectX; FbxAxisSystem SceneAxisSystem = FBXS->GetGlobalSettings().GetAxisSystem(); if(SceneAxisSystem != OurAxisSystem) { FbxAxisSystem::DirectX.ConvertScene(FBXS); } FbxSystemUnit SceneSystemUnit = FBXS->GetGlobalSettings().GetSystemUnit(); if( SceneSystemUnit.GetScaleFactor() != 1.0 ) { FbxSystemUnit::cm.ConvertScene( FBXS ); } if (FBXI) FBXI->Destroy(); FbxNode* MainNode = FBXS->GetRootNode(); int NumKids = MainNode->GetChildCount(); FbxNode* ChildNode = NULL; for (int i=0; i<NumKids; i++) { ChildNode = MainNode->GetChild(i); FbxNodeAttribute* NodeAttribute = ChildNode->GetNodeAttribute(); if (NodeAttribute->GetAttributeType() == FbxNodeAttribute::eMesh) { FbxMesh* Mesh = ChildNode->GetMesh(); if (UsePositionOnly) { NumVertices = Mesh->GetControlPointsCount();//number of vertices MyV = new XMFLOAT3[NumVertices]; for (DWORD j = 0; j < NumVertices; j++) { FbxVector4 Vertex = Mesh->GetControlPointAt(j);//Gets the control point at the specified index. MyV[j] = XMFLOAT3((float)Vertex.mData[0], (float)Vertex.mData[1], (float)Vertex.mData[2]); } NumIndices = Mesh->GetPolygonVertexCount();//number of indices MyI = (DWORD*)Mesh->GetPolygonVertices();//index array } else { FbxLayerElementArrayTemplate<FbxVector2>* uvVertices = NULL; Mesh->GetTextureUV(&uvVertices); int idx = 0; for (int i = 0; i < Mesh->GetPolygonCount(); i++)//polygon(=mostly triangle) count { for (int j = 0; j < Mesh->GetPolygonSize(i); j++)//retrieves number of vertices in a polygon { FBXVTX myVert; int p_index = 3*i+j; int t_index = Mesh->GetTextureUVIndex(i, j); FbxVector4 Vertex = Mesh->GetControlPointAt(p_index);//Gets the control point at the specified index. myVert.Position = XMFLOAT3((float)Vertex.mData[0], (float)Vertex.mData[1], (float)Vertex.mData[2]); FbxVector4 Normal; Mesh->GetPolygonVertexNormal(i, j, Normal); myVert.Normal = XMFLOAT3((float)Normal.mData[0], (float)Normal.mData[1], (float)Normal.mData[2]); FbxVector2 uv = uvVertices->GetAt(t_index); myVert.TextureCoord = XMFLOAT2((float)uv.mData[0], (float)uv.mData[1]); if ( myVertsMap.find( myVert ) != myVertsMap.end() ) myInds.push_back( myVertsMap[ myVert ]); else { myVertsMap.insert( std::pair<FBXVTX, int> (myVert, idx ) ); myVerts.push_back(myVert); myInds.push_back(idx); idx++; } } } } } } } else { hr = E_FAIL; MessageBox(hWnd, TEXT("Failed to create the FBX Manager"), TEXT("ALM"), MB_OK); } return hr; } bool operator < ( const FBXVTX &lValue, const FBXVTX &rValue) { if (lValue.Position.x != rValue.Position.x) return(lValue.Position.x < rValue.Position.x); if (lValue.Position.y != rValue.Position.y) return(lValue.Position.y < rValue.Position.y); if (lValue.Position.z != rValue.Position.z) return(lValue.Position.z < rValue.Position.z); if (lValue.TextureCoord.x != rValue.TextureCoord.x) return(lValue.TextureCoord.x < rValue.TextureCoord.x); if (lValue.TextureCoord.y != rValue.TextureCoord.y) return(lValue.TextureCoord.y < rValue.TextureCoord.y); if (lValue.Normal.x != rValue.Normal.x) return(lValue.Normal.x < rValue.Normal.x); if (lValue.Normal.y != rValue.Normal.y) return(lValue.Normal.y < rValue.Normal.y); return(lValue.Normal.z < rValue.Normal.z); }  
    • By Karol Plewa
      I am working on a project where I'm trying to use Forward Plus Rendering on point lights. I have a simple reflective scene with many point lights moving around it. I am using effects file (.fx) to keep my shaders in one place. I am having a problem with Compute Shader code. I cannot get it to work properly and calculate the tiles and lighting properly. 
      Is there anyone that is wishing to help me set up my compute shader?
      Thank you in advance for any replies and interest!
    • By fishyperil
      I'm looking for some references that could help me learn how to program some really basic 2D enemy behaviours.
      I wasn't sure whether to post this here or in the AI section but I think it might be more suitable to be posted here since it has more to do with basic maths than any AI related algorithms.
      Could anyone help recommend some resources (books, posts, videos) that could help me understand how to properly implement the basics of enemy movement in 2d games ? So far I've only managed to get them to chase the player character and to stop moving on collision, but the movement is pretty unrealistic and once the collision occurs the enemies all "pile up" on the player character. I'm doing this in C++ so no guides that explain how to script this using an engine api please.
  • Advertisement