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lizby
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Joined: 17/05/2016
Location: United States
Posts: 3378

Posted: 01:27am 17 May 2021

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On my F4 (IPS display, if it matters), I see the following:

> ?hex$(rgb(yellow))
FFFF00
> pixel 700,110,rgb(yellow)
> ?hex$(pixel(700,110))
F8FC00

Why aren't they the same? The same thing happens with CIRCLE and LINE. The problem that I have is that PIXEL(x,y) doesn't give me what appears to have been written with PIXEL x,y,somecolor (and I'm testing for a color match).

This is with "ARMmite MMBasic Version 5.07.00b12"

The same occurs on "ARMmite MMBasic Version 5.07.00b8" with an ili9341_16 LCD.

PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed

disco4now

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Joined: 18/12/2014
Location: Australia
Posts: 1003

Posted: 01:52am 17 May 2021

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All F4 display drivers use RGB565. So do an AND with F8FCF8 to see what your color really is.

Latest F4 Latest H7 FotS

phil99

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Joined: 11/02/2018
Location: Australia
Posts: 2642

Posted: 02:09am 17 May 2021

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Ditto with "ARMmite MMBasic Version 5.07.00b12" and standard "OPTION LCDPANEL ILI9341_16, RLANDSCAPE"

> cls &hFFFF00
> ? hex$(pixel(100,100))
F8FC00
>
> cls &H00FFFF
> ? hex$(pixel(100,100))
FCF8
> cls &HFF00FF
> ? hex$(pixel(100,100))
F800F8
> cls &HFFFFFF
> ? hex$(pixel(100,100))
F8FCF8
>
Because it's RGB565 not RGB888

From the manual:-

16-bit interface to SSD1963, ILI9341 and OTM8009A Based LCD Displays
The Armmite F4 drives the SSD1963 and some other 16-bit parallel bus LCD displays. For for extra speed the
SSD1963 controllers run with a reduced colour range (65 thousand colours RGB565) compared to 16 million
colours with the normal 8-bit interface. SPI touch is supported. The ILI9341 16 bit LCD that is purchased with
the STM32F407VET6 development board, while only 320*240 pixels, plugs directly into the board via the 32
pin FSMC connector. All other LCD panels will require an adaptor board.

lizby
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Joined: 17/05/2016
Location: United States
Posts: 3378

Posted: 12:54pm 17 May 2021

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Thanks, that explains it. In vegipete's CMM2 Renewed Defense of the Green Hills the bounding color of a circle is used to detect collision of an incoming missile with an explosion. On the F4, there was no match.

I fixed it by beginning by writing a pixel of the desired color, reading it back and, and then doing the collision detection using that saved RGB565 version of the color.

Yes, ANDing the color with &HF8FCF8 gives the right color on the F4.

~
Edited 2021-05-17 22:56 by lizby

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