Here’s a quick peek into some of the test and debug strategae I’m using…<\/p>\n
One of the great hazards of C++ is object leaks. To mitigate this, I have a base object that everyone descends from, called MeObjectBase. My descendant object constructors all look like<\/p>\n
\nMeRenderWorld::MeRenderWorld(int width, int height) : MeObjectBase(\"MeRenderWorld\")\n{ ... }\n<\/pre>\nThen we can print a tally of current objects by type name. But all that text-dictionary lookup can be expensive! So there’s a global boolean to enable or disable count-by-name. Even when disabled, the total number of objects is tracked.<\/p>\n
Malloc<\/h3>\n
Like object leaks, memory leaks are alway looming. The main code never calls malloc or free directly. Instead, some wrappers are used which keep a tally of how much memory has been allocated and freed, and how many pointers have been allocated and freed. A few bytes at the beginning of the block hold the size. These static methods on MeObjectBase.<\/p>\n
\nclass MeObjectBase\n{\npublic:\n ... \n static void *malloc(size_t bytes);\n static void reallocAt(void **ptr, size_t bytes);\n static void freeAt(void **ptr);\n};\n<\/pre>\nUnit Testing<\/h3>\n
I’ve been coding since I was 12. That’s forty years now, but who’s counting. The only significant thing I’ve learned in the last twenty or so is the joy and beauty of organized unit tests. I used to do unit tests, without realizing it: I’d write some code at the top of main() to call the new function, print out the result, and quit. Then I’d delete the test and continue development. <\/p>\n
I’ve also often written little test apps alongside my “real app” to exercise libraries.<\/p>\n
Anyway, yeah, unit testing. For Metareal, I’m just running a small command line app that tallies up trues and falses and prints the result at the end.<\/p>\n
Why not use an existing C++ unit testing framework? No great reasons, but among them: Tends to run slower as files are scanned or preprocessed for tests, adds code I don’t know that well. On the other hand, testing frameworks typically let you run single tests if needed. And I have to explicitly add every test function to main(). Oh well, is a tradeoff.<\/p>\n
Here’s what some tests look like:<\/p>\n
\n\/\/ A typical \"main method\" for a test file\nvoid allMatrixTests()\n{\n castingFloatToVec4();\n vec4ToVec3Tests();\n matrixRowColumnExtracts();\n matrixTests();\n matrixTestWTranslate();\n matrixTestLTranslate();\n vectorCallTest();\n basicMatrixMathFun();\n}\n\n\/\/ A typical assertion\n float m03 = m4(0,3);\n ASSERT_EQUALS_FLOAT(\"col\/row\", 3, m03);\n\n\/\/ Implementation of one of the assertions\n#define ASSERT_EQUALS_INT(_message,_want,_got) assertEqualsInt(1,__LINE__,_message,#_want,#_got,(long long)_want,(long long)_got)\nvoid assertEqualsInt(int sayIt,int line,cc message,cc wantS,cc gotS,long long want,long long got)\n{\n g.assertions++;\n if(got == want)\n {\n g.passes++;\n }\n else\n {\n g.fails++;\n assertLogFail(\"%6d. FAIL %4d %s %s(%lld) != %s(%d)\\n\",g.fails,line,message,wantS,want,gotS,got);\n }\n}\n<\/pre>\nThe last assertion I make is that all the memory and objects have been freed. Here’s a happy output.<\/p>\n
\n\n currentCount: 0\nconstructorCount:3801\n copyCount: 0\n everCount:3801\n mallocCount:6249\n freeCount:6249\n unfreedCount: 0\n mallocBytes:2363449281\n freedBytes:2363449281\n unfreedBytes: 0\n BitmapThing: 0 2 3\n Ham1: 0 1 1\n IfThing: 0 2 6\n IxMover2: 0 2 8\n MeCollisionVolume: 0 10 134\n MeGaud: 0 3 34\n MeGeometry: 0 1001 1541\n MeHam: 0 1 1\n MeITexture: 0 4 81\n MeLru: 0 2 3\n MePart: 0 1000 1190\n MeRenderParts: 0 3 59\n MeRenderWorld: 0 1 19\n MeTextureAtlas: 0 2 23\n MeTextureFloat4: 0 3 22\n MeThingKind: 0 1 8\n MeThingManager: 0 1 4\n MeVolume: 0 128 493\n MeVolumeWorld: 0 1 25\n MockFrameBuffer: 0 2 10\n MockMaterial: 0 3 67\n MockRenderer: 0 3 28\n a: 0 3 3\n b: 0 1 1\n unknown: 0 3 37\n 0. ok undisposed objects 0(0) == MeObjectBase::currentCount(0)\n 0. ok undisposed mallocs 0(0) == MeObjectBase::mallocCount - MeObjectBase::freeCount(0)\ntest results: 7551 pass \/ 7551 assertions (0.686 seconds)\n---------------------\n aok\n---------------------\nProgram ended with exit code: 0\n<\/pre>\nThing to notice: the total runtime for these tests is about a second. It covers the math, part and triangle-list management, many, many collision and volume intersection cases. It does not cover actual, live OpenGL code.<\/p>\n
Debug Logging<\/h3>\n
Little to say here, I have a couple of log methods, which take arguments like printf. Listeners can be added.<\/p>\n
Debug Global Booleans<\/h3>\n
Aaah, yes, debugging realtime code can be tricky. To help, when running the realtime app I map control-0 through control-9 directly to ten globally accessible booleans. Sometimes I’ll add some code to a deep, inner function which does something special based on those booleans. Then I can trigger it at will while running. Works nicely with breakpoints.<\/p>\n
Well, Ok<\/h3>\n
That’s just some of the goodies in play.<\/p>\n","protected":false},"excerpt":{"rendered":"
Here’s a quick peek into some of the test and debug strategae I’m using… Base Object One of the great hazards of C++ is object leaks. To mitigate this, I have a base object that everyone descends from, called MeObjectBase. My descendant object constructors all look like MeRenderWorld::MeRenderWorld(int width, int height) : MeObjectBase(“MeRenderWorld”) { … […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[],"class_list":["post-74","post","type-post","status-publish","format-standard","hentry","category-3"],"jetpack_featured_media_url":"","_links":{"self":[{"href":"http:\/\/metareal.net\/blog\/index.php?rest_route=\/wp\/v2\/posts\/74","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/metareal.net\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/metareal.net\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/metareal.net\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/metareal.net\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=74"}],"version-history":[{"count":1,"href":"http:\/\/metareal.net\/blog\/index.php?rest_route=\/wp\/v2\/posts\/74\/revisions"}],"predecessor-version":[{"id":75,"href":"http:\/\/metareal.net\/blog\/index.php?rest_route=\/wp\/v2\/posts\/74\/revisions\/75"}],"wp:attachment":[{"href":"http:\/\/metareal.net\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=74"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/metareal.net\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=74"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/metareal.net\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=74"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}