Solar Sailor is done!

I've submitted a "completed" version of Solar Sailor to the Ludum Dare website.

Play the finished game

It's been an intense 48 hours but really satisfying now that I'm at the end of it. There's loads more I would have done if I had time, but there some things I was pretty happy with too. I'll post a more complete post-mortem here in a couple of days... once I've had some sleep.

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Assert no lock required

This is a technique I learnt about from Jason Gregory's excellent book, Game Engine Architecture (3rd Edition) . If you have a shared resource accessed by multiple threads, where you're fairly certain that it's only ever accessed by one thread at a time, you can use an assert() to check for this at debug time without having to pay the runtime cost of locking a mutex. The implementation is fairly straightforward: class UnnecessaryMutex { public: void lock() { assert(!_locked); _locked = true; } void unlock() { assert(_locked); _locked = false; } private: volatile bool _locked = false; }; #ifdef ENABLE_LOCK_ASSERTS #define BEGIN_ASSERT_LOCK_NOT_REQUIRED(mutex) (mutex).lock() #define END_ASSERT_LOCK_NOT_REQUIRED(mutex) (mutex).unlock() #else #define BEGIN_ASSERT_LOCK_NOT_REQUIRED(mutex) #define END_ASSERT_LOCK_NOT_REQUIRED(mutex) #endif Usage is equally straightforward: UnnecessaryMutex gMutex; void PossiblyOverlappingFunction...

Triangle bounding boxes in a single byte

Just thought of a way to store the bounding box for a single triangle in only one byte. It's not really practical or something you'd ever really want to use, but what the hell. Assume we have some kind of indexed mesh structure with a list of vertex positions and a list of triangle indices: struct Mesh { std::vector<vec3> verts; std::vector<uvec3> triangles; }; We can find the bounding box of a triangle by taking the min and max of all three vertices: vec3 Mesh::lowerBound(uint32_t tri) const { vec3 v0 = verts[triangles[tri].x]; vec3 v1 = verts[triangles[tri].y]; vec3 v2 = verts[triangles[tri].z]; return min(min(v0, v1), v2); } vec3 Mesh::upperBound(uint32_t tri) const { vec3 v0 = verts[triangles[tri].x]; vec3 v1 = verts[triangles[tri].y]; vec3 v2 = verts[triangles[tri].z]; return ...

LD_DEBUG

Posting this mainly as a reminder to myself... If you ever find yourself needing to figure out a dynamic library loading problem on Linux, LD_DEBUG can be a massive help. This is an environment variable you can set to make the dynamic linker print out a ton of useful diagnostic info. There are a number of different values which control the amount and type of diagnostics printed. One of the values is help; if you set LD_DEBUG to this and run executable it will print out a list of all the available options along with brief descriptions. For example, on my Linux workstation at the office: > LD_DEBUG=help cat Valid options for the LD_DEBUG environment variable are: libs display library search paths reloc display relocation processing files display progress for input file symbols display symbol table processing bindings display information about symbol binding versions display version dependencies all all previous options combi...

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