SUBSIM Radio Room Forums - View Single Post - Realism- and gameplay-related hardcode fixes for SH3.EXE

Stiebler · 01-09-11, 03:13 PM

@H.sie:
You identified earlier a diving tank and another variable, tentatively thought to be possibly a depth rudder ( = hydroplane). (Seen at code SH3Sim.act + 0x7527, and indexed through register ecx.)

I have now checked out this code, and there appear to be five variables involved, all indexed by ecx. Since there is no way of identifying these by constant memory addresses, I shall identify them by the last three digits of their addresses (these last three digits are probably the same for you too). The values were checked for a simple dive (‘D’-key) from surface, and a crash-dive (‘C’-key) from surface, at TC = 1. I’m using a IXC boat.

xxxxx170: involved in dive + crash-dive. Value reaches a maximum of about +0.5235 in mid-dive, averages zero when at requested depth.
xxxxx05c: value remains steady at 0.0 throughout (dive + crash-dive). However, the calling code leads to:
xxxxx18C: involved in dive +crash-dive. This value rises rapidly from 0.0000 to 1.0000, and presumably represents the memory location of the diving tank.
xxxxx144: involved in dive + crash-dive. Value is frequently the negative value of xxxxx170, but the values differ slightly during the dive. Value averages zero when at requested depth.
xxxxx1A0: involved in crash-dive only. Value rises very fast from 0.0000 to 1.0000, faster than xxxxx18C. It appears to represent (correctly) a quick-diving tank for crash-dives. After the U-boat reaches the crash-dive depth, the value falls very fast to 0.5000.

Comments:
We know already that a crash-dive in SH3 reaches its depth (80 metres here) faster than a high-speed dive to 80 metres. This is obviously modelled correctly with SH3 - well done, devs.
The ‘crash-dive blues’ occurs when a crash-dive is interrupted by changing the depth before the crash-dive has completed. When this happens, the U-boat does not level out correctly, but has a downwards angle. The bug affects all the super-mods, but is particularly noticeable with NYGM.

When a crash-dive is interrupted, the value of xxxxx1A0 does not return to 0.5000, but remains at 1.0000. This is the only difference I have detected (yet) between a completed crash-dive, an interrupted crash-dive, and a simple dive. When the NYGM U-boat is set to slow ahead, after an interrupted crash-dive, it sinks. When the speed is set to half-ahead, the U-boat returns to the depth set by the player when he interrupted the crash-dive. There is *no difference* between the values of the five variables shown above in either circumstance.

This is hard to interpret. Is it possible that that xxxx170 and xxxxx144 can be hydroplanes/depth-rudders, and the difference in water flow over them at different submerged speeds causes a gain or loss of depth? That is how hydroplanes are intended to function. But in that case, why is there not a severe angle on the hydroplanes at slow underwater speeds, when the boat is sinking, but wishes to rise?

Stiebler.

01-09-11, 03:13 PM	#864
Stiebler Fuel Supplier Join Date: Oct 2005 Location: London, UK Posts: 1,237 Downloads: 29 Uploads: 4	Diving tank again @H.sie: You identified earlier a diving tank and another variable, tentatively thought to be possibly a depth rudder ( = hydroplane). (Seen at code SH3Sim.act + 0x7527, and indexed through register ecx.) I have now checked out this code, and there appear to be five variables involved, all indexed by ecx. Since there is no way of identifying these by constant memory addresses, I shall identify them by the last three digits of their addresses (these last three digits are probably the same for you too). The values were checked for a simple dive (‘D’-key) from surface, and a crash-dive (‘C’-key) from surface, at TC = 1. I’m using a IXC boat. xxxxx170: involved in dive + crash-dive. Value reaches a maximum of about +0.5235 in mid-dive, averages zero when at requested depth. xxxxx05c: value remains steady at 0.0 throughout (dive + crash-dive). However, the calling code leads to: xxxxx18C: involved in dive +crash-dive. This value rises rapidly from 0.0000 to 1.0000, and presumably represents the memory location of the diving tank. xxxxx144: involved in dive + crash-dive. Value is frequently the negative value of xxxxx170, but the values differ slightly during the dive. Value averages zero when at requested depth. xxxxx1A0: involved in crash-dive only. Value rises very fast from 0.0000 to 1.0000, faster than xxxxx18C. It appears to represent (correctly) a quick-diving tank for crash-dives. After the U-boat reaches the crash-dive depth, the value falls very fast to 0.5000. Comments: We know already that a crash-dive in SH3 reaches its depth (80 metres here) faster than a high-speed dive to 80 metres. This is obviously modelled correctly with SH3 - well done, devs. The ‘crash-dive blues’ occurs when a crash-dive is interrupted by changing the depth before the crash-dive has completed. When this happens, the U-boat does not level out correctly, but has a downwards angle. The bug affects all the super-mods, but is particularly noticeable with NYGM. When a crash-dive is interrupted, the value of xxxxx1A0 does not return to 0.5000, but remains at 1.0000. This is the only difference I have detected (yet) between a completed crash-dive, an interrupted crash-dive, and a simple dive. When the NYGM U-boat is set to slow ahead, after an interrupted crash-dive, it sinks. When the speed is set to half-ahead, the U-boat returns to the depth set by the player when he interrupted the crash-dive. There is no difference between the values of the five variables shown above in either circumstance. This is hard to interpret. Is it possible that that xxxx170 and xxxxx144 can be hydroplanes/depth-rudders, and the difference in water flow over them at different submerged speeds causes a gain or loss of depth? That is how hydroplanes are intended to function. But in that case, why is there not a severe angle on the hydroplanes at slow underwater speeds, when the boat is sinking, but wishes to rise? Stiebler. __________________ NYGM Tonnage War Mod - More than a mod: it's an experience!