Announcement - PropGFX Lite Binary Released

Oldbitcollector (Jeff)

Here's my latest refinement to the GUI Slider Control.

The control may be positioned anywhere on the screen. Multiple controls may also be used.

Code is attached!

OBC

Dr_Acula

I've been doing some experiments with the standard propeller colors as I have noticed that yellows in particular come out very dark on the display.

There is a demo palette and reds, greens, blues and purple all are fairly correct. However, the brightest yellow is a dark gold color and comparing it with a standard palette, a Luminance of 0.86 is displaying on the screen at a value of about 0.5.

If we limit the palette to the closest colors to the true propeller palette and then run an image through the Floyd Steinberg transform, then these colors will end up corrected. For instance, if nothing brighter than a dark gold is available, the F-S transform will end up dithering this color with white or a light gray. When displayed on the propeller screen this will have the effect of lightening the color.

Looking at the pictures, there are two palettes. One of these has values along the top with variable maximum luminance values. These have been tweaked so that that the yellows are darker to more closely match the real palette.

There is a splash screen and some photos of the two versions. Colors don't come out as bright on a photo compared to a real screen (see the white background), but on the text, the color of the yellow is lighter on one than the other.

Finally there is a picture of Mario and this looks much closer to the real thing.

Some vb.net code to create the palette as close as possible to a real propeller palette.

Private Sub CreateTVPalette(ByVal Palette(,) As Integer)
        ' create the TV palette (minus the super saturated colors)
        Dim i As Integer
        Dim n, S, L, Lmax As Double
        Dim Mycolor As Color
        i = 0 ' counter
        S = 1.0 ' approx value , previously using 0.7 but make it 1.0
        ' see the palette tab for experiments with a better palette with darker yellows
        For x = 0 To 15
            n = (15 - x) - 3.5 ' calculate hue
            If n < 0 Then n += 16 ' rotate around the color wheel
            Select n
                Case 11.5 : Lmax = 1 ' yellows are much darker than blues looking at the prop palette program
                Case 10.5 : Lmax = 0.95
                Case 9.5 : Lmax = 0.9
                Case 8.5 : Lmax = 0.8
                Case 7.5 : Lmax = 0.7
                Case 6.5 : Lmax = 0.6
                Case 5.5 : Lmax = 0.6
                Case 4.5 : Lmax = 0.55
                Case 3.5 : Lmax = 0.5
                Case 2.5 : Lmax = 0.5
                Case 1.5 : Lmax = 0.6
                Case 0.5 : Lmax = 0.8
                Case 15.5 : Lmax = 0.9
                Case 14.5 : Lmax = 0.9
                Case 13.5 : Lmax = 1
                Case 12.5 : Lmax = 1
            End Select
            'H = n / 16 ' hue
            For y = 5 To 1 Step -1
                L = Lmax * y / 6 ' luminance 
                Mycolor = HSL_to_RGB((n / 16), S, L)
                Palette(i, 0) = Mycolor.R ' red value
                Palette(i, 1) = Mycolor.G ' green value
                Palette(i, 2) = Mycolor.B ' blue value
                Palette(i, 3) = x * 16 + 9 + y ' calculate the propeller byte value
                i += 1
            Next
        Next
        ' now do the grays
        i = 0
        For x = 80 To 85
            For y = 0 To 2
                Palette(x, y) = i * 51 ' scale of grays 0 to 255 step 51
            Next
            Palette(x, 3) = i + 2 ' propeller byte value
            i += 1 ' increment counter
        Next
    End Sub

Daviduk

Very impressive work indeed. Is PropGFX Or PropGFX Lite available in any form still?

yeti

Maybe you have some luck with archive.org: https://web.archive.org/web/20111018074206/http://www.propgfx.co.uk/?page_id=14

Publison

Also tried Way Back Machine. Mostly dead ends. Started in 2012 working forward.

Ariba

Daviduk wrote: »

Very impressive work indeed. Is PropGFX Or PropGFX Lite available in any form still?

You can build that with any Propeller board with a 64kB EEPROM (Quickstart, FLiP). Add the 3 resistors for TV output, and load the binaries into the EEPROM with the Spin files from this post:
https://forums.parallax.com/discussion/comment/1016014/#Comment_1016014

The documentation PDF is here:
https://forums.parallax.com/discussion/comment/993447/#Comment_993447

Andy

Daviduk

Thank you

Daviduk

This is just a general enquiry - but could hypothetically PropGFX be used as to process graphics, accessed from a physical area of memory, running as purely a graphics processor alongside another CPU?

I'm thinking of a situation with a machine similar in structure either a ZX81 or Spectrum, where a specific area of memory is accessed to change the image, rather than accessing by commands.

I'm not a hardware person myself, but am bouncing ideas for a few things with others.

Thanks in advance!

yeti

Propeller as VGA output for the ZX81: http://zx81vga.ws-nbg.de/main.php

I think the Propeller is memory mapped in there.

Daviduk

That is fascinating Yeti, thank you. Have been looking for examples of this.

It does look like he's using the Propeller as a supplement to the internal Z80, which is similar to what I was looking into.

I'll have to see if he's done a write-up anywhere.

Daviduk

Werner's site is very fascinating - but it looks like he uses his own graphics code rather than PropGFX

However it has given a few ideas, so was definately worth checking out.

yeti

I pointed to his stuff only because he uses a Propeller attached to the bus of a different processor.
This was not an answer related to PropGFX.
May this thread forgive me for this...