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Amnesie
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Joined: 30/06/2020
Location: Germany
Posts: 396

Posted: 04:53pm 25 Mar 2023

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Hello,

I am trying to understand the framebuffer and simply don't get it. All I want to do is this example Peter showed on YouTube (https://www.youtube.com/watch?v=dLk7JgB3YCY), where he has a background image and a moving sine wave on the top layer.

The manual is good, but does not help how to begin with.

I think first of all I have to load my desired image

load image "grid"

Then create a framebuffer with

framebuffer create

now (in my mind) I've created a framebuffer with my background image "grid"

Then I want to put my moving sine function on top of that with

framebuffer layer

Because the manual says: "Allocates 38400 bytes of variable memory to a second display layer. This
layer sits on top of the main display." So exactly what I want. now I am drawing my moving sine wave on top, but nothing works the screen goes black.

This is always my problem with complex commands, I read the manual, but I don't know how to start at all. Is there anywhere Peters YouTube example of it? I've looked at Martins framebuffer examples with sprites but they are all too complex to begin with.

My final application is my ECG, which works good but needs some grid in the background and I thought it would be much better with framebuffer than drawing horzontal and vertical lines.

This is my ECG, which works good so far, but a background grid would be much nicer.

SetTick 10, ekg_interrupt 'Abtastrate 100Hz
SetPin GP28, AIN
SetPin GP25, DOUT
Font 2,1
CLS c
RTC gettime

'Tiefpass
a0t = 0.1565712872
a1t = 0.2651425745
a2t = 0.1565712872
b1t = -0.5695259524
b2t = 0.1958111014

'Notch
a0n = 0.7857841106
a1n = -8.4007020142E-16
a2n = 0.7857841106
b1n = -8.4007020142E-16
b2n = 1.1915682213

Do
If x>MM.HRes Then
x=-1
'Save image "bild.bmp"
EndIf
Loop

ekg_interrupt:
'Show Time
Text 120,210,Time$
'Increment
x=x+1
ekg = Pin(GP28)
'Filter 1
sn_2 = s_n1
s_n1 = s_n
s_n = ekg
g_n2 = g_n1
g_n1 = g_n
g_n = s_n*a0t+s_n1*a1t+s_n2*a2t+g_n1*b1t+g_n2*b2t
ekg = g_n
'Filter 2
sn_2 = s_n1
s_n1 = s_n
s_n = ekg
g_n2 = g_n1
g_n1 = g_n
g_n = s_n*a0n+s_n1*a1n+s_n2*a2n+g_n1*b1n+g_n2*b2n
ekg = g_n
'Drawing
Line x,0,x+1,MM.HRes,1,BF
Line x-1,ekg_alt*140,x,ekg*140,1
ekg_alt = ekg
IReturn

Greetings
Daniel
Edited 2023-03-26 03:08 by Amnesie

matherp
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Joined: 11/12/2012
Location: United Kingdom
Posts: 9139

Posted: 05:19pm 25 Mar 2023

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MODE 2
FRAMEBUFFER create
FRAMEBUFFER layer
For x=1 To MM.HRes-1 Step 16
Line x,0,x,MM.VRes-1
Next
For y=1 To MM.VRes-1 Step 16
Line 0,y,MM.HRes-1,y
Next
i=0
Do
FRAMEBUFFER write f
CLS
For j=i To MM.HRes-1+i
l=k
k=Sin(j/MM.HRes*2*Pi)
If j<>i Then Line j-i-1,l*100+MM.VRes/2,j-i,k*100+MM.VRes/2,,RGB(red)
Next
Inc i
FRAMEBUFFER copy f,l,b
Loop

Edited 2023-03-26 03:27 by matherp

Amnesie
Guru

Joined: 30/06/2020
Location: Germany
Posts: 396

Posted: 07:02pm 25 Mar 2023

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Thank you a lot, this helped me to understand how it works!

Greetings
Daniel

Martin H.

Guru

Joined: 04/06/2022
Location: Germany
Posts: 1115

Posted: 07:30pm 25 Mar 2023

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Hi Daniel,

Framebuffer N is the actual screen

Framebuffer F is the Buffer which is never visible but you can hiddenly draw on it and copy it to Framebuffer N or L

Framebuffer L is a Layer, Everything that is written or drawn here is placed over the Screen like a foil without changing the content of screen(n)
(Like a 100% opaque Layer in Photoshop).An exception here are black pixels, these are transparent in the layer, so the content of the screen(n) "shines through" all black pixels on Framebuffer L

I hope that was somewhat understandable

for example look at my "on the road again" demo, here the screen is drawn hidden on Framebuffer F and copied to N when ready,
the Car is shown on Framebuffer L so that it doesn't affect the background

Cheers
Mart!n
Edited 2023-03-26 05:55 by Martin H.

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