It's not directly possible. Two approaches to fake it that I can see:
1) have multiple SFX for one sound, each representing a different "loudness", and then pick depending on distance
2) (hacky and more advanced, but more powerful) use direct memory accesses to rewrite SFX on the fly - see https://www.lexaloffle.com/bbs/?tid=2341
Thank you @krajzeg.
Yeah, #1 was what I assumed I'd have to do.
I will study up on #2 though.
Thanks again!
Lazzoak, I'm working on it. Halfway there. Should be done by tomorrow evening.
print("volume="..volume)
if (btn(0)) volume-=1
if (btn(1)) volume+=1
volume=mid(-8,volume,8)
reload(12800,12800,affectfx*68)
for i=0,affectfx-1 do
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If you can do it before me though, that's fine. :)
Complete !
Anything higher than 0 increases volume on all the other stuff.
Pretty sure the start of this code can lead to all kinds of interesting things like change pitch, have percussion only, and change tempo. And of course it could be optimized tons. :)
HOPE THIS HELPS !
Wow, thank you @dw817
I'm studying this as we speak. I'm still somewhat new to pico 8 so working directly with memory is unfamiliar territory. But seems time I learn, so this gives me something to dissect.
@dw817 seriously?
bit={}
for i=7,0,-1 do
if n>=2^i then
bit[i]=1
n-=2^i
else
bit[i]=0
end
end
a=bit[1]+bit[2]*2+bit[3]*4
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if you are not confortable with bit math, don't offer "helper" functions to beginners.
@lazzoak as per @krajzeg link, use bit masking to read/write sound volume.
-- chart sfx volume cls() fillp(0x0f0f) rectfill(0,64,32,64-8,0x1) fillp() -- change to chart another sfx bank local sfx_id=0 -- starting address local mem=0x3200+68*sfx_id for i=0,31 do -- read note local s=peek2(mem) -- bits 9-11 rebased to [0,7] range local vol=shr(band(0x0e00,s),9) -- print curve pset(i,64-vol,5+vol) mem+=2 end |
I just wanted to get it done since no-one had ever provided working P8 source-code to date to change volume - and it works. And 3-stars. Woo hoo ! Someone must've liked it !
Wow, @freds72. What an attitude you have. :D
Haven't your parents ever told you if you don't have anything nice to say, don't say anything at all ? Have I ever said something like what you did to you or anyone else ? Ever ? Don't think so.
Despite your dour attitude, you provided optimization which is the correct SHR. And I thank you for that. I knew it was SHL or SHR, I just have trouble with those. I'll sit down with that later and make a bit-function to help me (mostly) and perhaps others in the future.
As for you lazzoak, glad to help ! Writing that code was a learning experience for me too.
Do you understand the SHR command ? It's more complex than simpler exponent. Here is some information on it:
Ah ! Just wrote up a new bit library and quashed (is that a word ?) the massive code for early bit-handling.
New functions are: + bitget() .. get number w string chars 0-7 + bitmod() .. modify number w string chars 0-7 + bitset() .. set bits in number from chars 0-7 + bitclr() .. clear bits in number from chars 0-7 + bittest().. returns true or false on bit set |
Which leaves only this to read and write volume now:
n=peek(12800+i*68+j) p=bitget(n,"123",1) p+=volume p=mid(0,p,7) n=bitmod(n,p,"123",1) poke(12800+i*68+j,n) |
Here is new cart:
@dw817
Hi, I wonder how to change volume of BGM and found this entry. Your code works well. Thank you!
I referred your code and found some APIs(band, bor, shr, and shl) are deprecated now. I rewrote as the following:
-- return masked bits -- _val target value -- _mask contains 0-7 bit mask -- _shr for shift right function bitget(_val,_mask,_shr) local result=0 for i=1,#_mask do _bit_pos=sub(_mask,i,i) result+=(_val&(1<<_bit_pos))>>_shr end return result end -- modify masked bits -- _val target value -- _mod modify value to be set -- _mask conrains 0-7 bit mask -- _shl for shift left function bitmod(_val,_mod,_mask,_shl) return bitclr(_val,_mask)|(_mod<<_shl) end -- clear masked bits -- _val target value -- _mask contains 0-7 bit mask function bitclr(_val,_mask) local result=_val for i=1,#_mask do _bit_pos=sub(_mask,i,i) result-=result&(1<<_bit_pos) end return result end |
FWIW using @freds72 code as a base I have the following. They can all be reduced to save tokens, but I thought I'd keep operations separate here, for clarity.
-- sets the volume of a single note in the given sfx
function set_volume(sfxid, note, value)
-- find the address to peek
local address=0x3200+68*sfxid+value*2
-- get the bytes
local bytes=%address
-- clear the the volume bits from the bytes
bytes=bytes&0xf1ff
-- shift the new volume bits
value=mid(0,value,7)<<9
-- use them as a bitmask
bytes=bytes|value
-- save the bytes
poke2(address,bytes)
end
-- sets the volume for a range of notes in the given sfx
function set_volumes(sfxid, start, values)
-- find the address to peek
local address=0x3200+68*sfxid+start*2
-- loop through the values
for _,value in ipairs(values) do
-- get the bytes
local bytes=%address
-- clear the the volume bits from the bytes
bytes=bytes&0xf1ff
-- shift the new volume bits
value=mid(0,value,7)<<9
-- use them as a bitmask
bytes=bytes|value
-- save the bytes
poke2(address,bytes)
-- move to the next note
address+=2
end
end
-- returns the volume of a note in the given sfx
function get_volume(sfxid, note)
-- find the address to peek
local address=0x3200+68*sfxid+note*2
-- get the bytes
local bytes=%address
-- extract the volume bits
local value=0x0e00&bytes
-- return the shifted volume bits
return value>>9
end |
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