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Move page script moved page Using OnUpdate correctly to WoW:Using OnUpdate correctly without leaving a redirect
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This page is a guide on '''using OnUpdate correctly'''. | |||
== How Often Is It Called == | == How Often Is It Called == | ||
The game engine will call your OnUpdate function once each frame. This is (in most cases) extremely excessive. | The game engine will call your OnUpdate function once each frame. This is (in most cases) extremely excessive. | ||
*'''Ctrl + R''' to see the FPS on screen. | |||
<!--- | |||
added: *'''Ctrl + R''' to see the FPS on screen. | |||
- Crixi 2008-08-23 | |||
---> | |||
== When Is It Called == | == When Is It Called == | ||
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... | ... | ||
<Scripts> | <Scripts> | ||
<OnLoad> | <OnLoad>self.TimeSinceLastUpdate = 0 </OnLoad> | ||
<OnUpdate | <OnUpdate function="MyAddon_OnUpdate" /> | ||
</Scripts> | </Scripts> | ||
</Frame> | </Frame> | ||
</Ui> | </Ui> | ||
The important part for us is the "arg1 | The important part for us is the local "elapsed" (Global is arg1) parameter that we're passing to our function. This is a variable that's being inherited from the WoW system telling us how long it's been since the last update call cycle. | ||
; your_lua_file.lua | ; your_lua_file.lua | ||
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-- Functions Section | -- Functions Section | ||
function MyAddon_OnUpdate(elapsed) | function MyAddon_OnUpdate(self, elapsed) | ||
self.TimeSinceLastUpdate = self.TimeSinceLastUpdate + elapsed; | |||
if ( | if (self.TimeSinceLastUpdate > MyAddon_UpdateInterval) then | ||
-- | -- | ||
-- Insert your OnUpdate code here | -- Insert your OnUpdate code here | ||
-- | -- | ||
self.TimeSinceLastUpdate = 0; | |||
end | end | ||
end | end | ||
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If you're doing things that require high accuracy in the frequency of the OnUpdate calls, the above code won't be accurate since every time it is called, you will lose milliseconds as the ''TimeSinceLastUpdate'' variable is reset to 0 (If it was 1.05 seconds since last update, it would take 0.05 more seconds until the next update than it should, assuming that one hits 1.0, otherwise it would be delayed by another 0.05, etc). The below code accounts for this, and has a ''while'' structure to make sure that if the players framerate is very low, it'll still do the updates as many times as is needed. | If you're doing things that require high accuracy in the frequency of the OnUpdate calls, the above code won't be accurate since every time it is called, you will lose milliseconds as the ''TimeSinceLastUpdate'' variable is reset to 0 (If it was 1.05 seconds since last update, it would take 0.05 more seconds until the next update than it should, assuming that one hits 1.0, otherwise it would be delayed by another 0.05, etc). The below code accounts for this, and has a ''while'' structure to make sure that if the players framerate is very low, it'll still do the updates as many times as is needed. | ||
function MyAddon_OnUpdate(elapsed) | function MyAddon_OnUpdate(self, elapsed) | ||
self.TimeSinceLastUpdate = self.TimeSinceLastUpdate + elapsed; | |||
while ( | while (self.TimeSinceLastUpdate > MyAddon_UpdateInterval) do | ||
-- | -- | ||
-- Insert your OnUpdate code here | -- Insert your OnUpdate code here | ||
-- | -- | ||
self.TimeSinceLastUpdate = self.TimeSinceLastUpdate - MyAddon_UpdateInterval; | |||
end | end | ||
end | end | ||
[[Category:HOWTOs|Use OnUpdate Correctly]] | [[Category:HOWTOs|Use OnUpdate Correctly]] | ||