Devcorner: Macros Are Evil

The joys of programming - hours spent scratching one's head whilst trying to figure out why the seemingly correct code does not produce correct results.

Hi, Charlie here. I used to post often.

Where was I? Ah, yes, this nugget of brain fudgery from the VDrift forums posted by NaN:
So I've spent some time today try to figure out why cars are still flying off in random directions when hitting curbs sometimes.

It turns out it is a bug in Bullet, to be more specific in the SIMD_DEGS_PER_RAD macro.

Code:

#define SIMD_PI           btScalar(3.1415926535897932384626433832795029)
#define SIMD_2_PI         btScalar(2.0) * SIMD_PI
#define SIMD_HALF_PI      (SIMD_PI * btScalar(0.5))
#define SIMD_RADS_PER_DEG (SIMD_2_PI / btScalar(360.0))
#define SIMD_DEGS_PER_RAD  (btScalar(360.0) / SIMD_2_PI)

The first one to spot it gets a virtual cookie.

For the answer visit the thread, I won't spoil it here. Instead, I'll post a screenshot, also sourced from said forums and taken by Stunt Rally author CrystalH.

 


For those who don't know, Stunt Rally is a friendly fork of VDrift.

Nhận xét

Đăng nhận xét

Bài đăng phổ biến từ blog này

The Battle of Four Square Junction

Hình ảnh
Well, I wanted a good game and I got one! Not having a definite idea I decided to roll dice to pick and layout terrain items such as hills, woods, buildings and road entry points and to deploy all my ready Origawn Rebellion forces. Somewhere in the Origawn Territory, Advance Guards clash. I had been having some fun experimenting with using a 3" grid for measuring only and with playing around with 2 grid units but in the end, based on the current size of the incomplete armies, I decided to just go with the 6" grid with a unit per grid square except in cases of massed battalions where 2 units could be in a square and artillery which takes two adjacent squares, one for the gun and one for the limbers, caissons and so forth. The armies deploy directly from the march. Both armies were composed of one cavalry and three infantry brigades supported by two batteries. The cavalry brigades were only two squadrons while the infantry brigades were composed of four 'companies' of i...
Đọc thêm

They're Back! Doug Miller 40mm Landsknechts are back!

Hình ảnh
Bless the internet, and, I suspect, the blogosphere. About 15 years ago, I bought three Doug Miller Landsknecht figures ( yes the author of the old Osprey Landsknect book ),  through the Michigan Toy Soldier Company if memory serves. I then found Doug's old website on line but by the time I had spare funds, it was gone. This spring I was surprised to receive an email from Doug saying that he had heard that I was looking for more of his figures. I didn't ask him how he knew but a  BIG  thank you to whoever tipped him off and gave him my email. 1525 (Doug Miller ) and Elastolin recruits. Anyway, when I got home from visiting family yesterday, the package was waiting on the kitchen table ( Of course).   I still don't have ample funds and don't realllly  need  more 16thC figures but do have a box full of Elastolin kits that I got cheap, BUT they are mostly duplicates of a few very active poses rather than the nice, useful, standing or advancing figures. Th...
Đọc thêm

Real Warfare 1242 Game

Hình ảnh
Real Warfare 1242 Game  Play Overview: Russia during the XIII century was a huge state, much larger than any other European country. Split by internal conflicts, and yet standing strong against numerous outer threats, it was attacked by the infamous Mongol Horde. They came suddenly and pierced through the country like a blazing arrow. The native people fought valiantly, led by a fierce warrior and prince, Prince Alexander Nevsky. Real Warfare: 1242, is a realistic real-time strategy game based on authentic historic events. It invites you to experience the glorious times of princes, knights and vast battles. The player's goal is to direct Alexander Nevsky through meticulously recreated historic battlegrounds and achieve the greatest of victories by repelling the attacks of Teutonic and Swedish knights, bringing Lithuania to peace and eliminating every single invader in 1242.                       The engine incorporates state-of...
Đọc thêm