6502/PLASMA
1
0
Fork 0
mirror of https://github.com/dschmenk/PLASMA.git synced 2025-01-02 12:33:07 +00:00
Code Issues Projects Releases Wiki Activity

Calc true NTSC color wheel values for RGB

Browse Source
This commit is contained in:
David Schmenk 2024-12-13 13:32:44 -08:00
parent 480b98e817
commit 331c5c2dea
1 changed files with 10 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
src/dhgr.tk/utils/dhgrrgb.pla
View File

@ -73,12 +73,20 @@ def luv2rgb(l, u, v)#3 // l = fix 1.7, u, v = fix s.15; return fix 0.8 * 3
end
def calcChroma(angle)#0
var r, g, b
var l, r, g, b
byte i
l = 256 - contrast
for i = 0 to 3
// Calculate and NTSC RGB for this DHGR pixel
r, g, b = luv2rgb(256 - contrast, cos(angle), sin(angle))
// According to what I could find out about the NTSC color wheel:
// Red maxes at 103.5 degrees
// Green maxes at 240.7 degrees
// Blue maxes at 347.1 degrees
r = max(0, l + (cos(angle - 104) >> 7))
g = max(0, l + (cos(angle - 241) >> 7))
b = max(0, l + (cos(angle - 347) >> 7))
//r, g, b = luv2rgb(256 - contrast, cos(angle), sin(angle))
ntscChroma[i*3 + RED] = (r + 2) >> 2
ntscChroma[i*3 + GRN] = (g + 2) >> 2
ntscChroma[i*3 + BLU] = (b + 2) >> 2