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// Project: Make Greyscale 
// Created: 2020-12-31

// show all errors
SetErrorMode(2)

// set window properties
SetWindowTitle( "Make Greyscale" )
SetWindowSize( 1024, 768, 0 )
SetWindowAllowResize( 1 ) // allow the user to resize the window

// set display properties
SetVirtualResolution( 1024, 768 ) // doesn't have to match the window
SetOrientationAllowed( 1, 1, 1, 1 ) // allow both portrait and landscape on mobile devices
SetSyncRate( 30, 0 ) // 30fps instead of 60 to save battery
SetScissor( 0,0,0,0 ) // use the maximum available screen space, no black borders
UseNewDefaultFonts( 1 ) // since version 2.0.22 we can use nicer default fonts


img1 = LoadImage("1_IDLE_004.png")
img2 = LoadImage("1_IDLE_004.png")

spr1 = CreateSprite(img1)
SetSpritePosition(spr1, 0, 200)

spr2 = CreateSprite(img2)
SetSpritePosition(spr2, GetSpriteWidth(spr1), 200)


do
    Print("Press <1> to convert to greyscale based on RED channel")
    Print("Press <2> to convert to greyscale based on GREEN channel")
    Print("Press <3> to convert to greyscale based on BLUE channel")
    Print("Press <4> to convert to greyscale based on ALPHA channel")
    Print("Press <5> to convert to greyscale based on average colour")
    Print("Press <SPACE> to reset colour")
    for k = 1 to 5
		if GetRawKeyPressed(k+48)
			MakeGreyscale(spr2, k)
		endif
	next k
	if GetRawKeyPressed(32)
		SetSpriteImage(spr2, LoadImage("1_IDLE_004.png"))
	endif
    Sync()
loop



function MakeGreyscale(spr, mode)
	img = GetSpriteImageID(spr)
	mb = CreateMemblockFromImage(img)
	size = GetMemblockSize(mb)
	for k = 12 to size-4 step 4
		b = GetMemblockByte(mb, k)
		g = GetMemblockByte(mb, k+1)
		r = GetMemblockByte(mb, k+2)
		a = GetMemblockByte(mb, k+3)
		select mode
			case 1
				SetMemblockByte(mb, k, r)
				SetMemblockByte(mb, k+1, r)
				SetMemblockByte(mb, k+2, r)
			endcase
			case 2
				SetMemblockByte(mb, k, g)
				SetMemblockByte(mb, k+1, g)
				SetMemblockByte(mb, k+2, g)
			endcase
			case 3
				SetMemblockByte(mb, k, b)
				SetMemblockByte(mb, k+1, b)
				SetMemblockByte(mb, k+2, b)
			endcase
			case 4
				SetMemblockByte(mb, k, a)
				SetMemblockByte(mb, k+1, a)
				SetMemblockByte(mb, k+2, a)
			endcase
			case 5
				avg = (r+g+b)/3
				SetMemblockByte(mb, k, avg)
				SetMemblockByte(mb, k+1, avg)
				SetMemblockByte(mb, k+2, avg)
			endcase
		endselect
	next k
	CreateImageFromMemblock(img, mb)
	DeleteMemblock(mb)
endfunction

SetWindowSize( 1024, 768, 0 )
SetVirtualResolution( 1024, 768 )
LoadImage(1,"yourspriteimge.png")

createShader()
CreateSprite(1, 1)
SetSpriteTransparency(1,1)
LoadSpriteShader(1, "bw.ps")
SetSpriteShader(1, 1)

//the next line is only there to show transparency with a background
bg=createsprite(LoadImage("anybackgroundimage.png")):SetSpriteDepth(bg,100)

SetSpritePosition(2, 100.0, 100.0)

resetTimer()
SetShaderConstantByName(1, "factor", 0, 0, 0, 0) //factor red blue green alpha

do

SetShaderConstantByName(1, "factor", 1, 1, 1, 1) //red green blue alpha set rgn to 1 like this for gray
//SetShaderConstantByName(1, "factor", 0.5, 0.6, 1.0, 1) //red green blue alpha
sync()

loop


function createShader()
file = OpenToWrite("bw.ps")
WriteLine(file,"uniform sampler2D texture0;")
//WriteLine(file,"uniform float agk_time;")
WriteLine(file,"varying mediump vec2 uvVarying;")
WriteLine(file,"uniform vec3 factor;")
WriteLine(file,"void main()")
WriteLine(file,"{")
WriteLine(file,"vec4 color = texture2D(texture0, uvVarying).rgba;")
WriteLine(file,"float grey = 0.21 * color.r + 0.71 * color.g + 0.07 * color.b;")
WriteLine(file,"vec4 color2 = vec4(color.rgb * (1.0 - factor) + (grey * factor), 1.0);")
WriteLine(file,"gl_FragColor = vec4(color2.r,color2.g,color2.b,color.a);")

WriteLine(file,"}")
CloseFile(file)
endfunction

SetWindowSize( 1024, 768, 0 )
SetVirtualResolution( 1024, 768 )
 LoadImage(1,"youimage.png") 

createShader()
CreateSprite(1,1)
MakeGreyscale(1)
do
    sync()  
loop

function MakeGreyscale(spr)
//Gray = 0.2126×Red + 0.7152×Green + 0.0722×Blue
    img = GetSpriteImageID(spr)
    mb = CreateMemblockFromImage(img)
    size = GetMemblockSize(mb)
    for k = 12 to size-4 step 4
        r = GetMemblockByte(mb, k)
        g = GetMemblockByte(mb, k+1)
        b = GetMemblockByte(mb, k+2)
        Gray = 0.2126*r + 0.7152*g + 0.0722*b
        SetMemblockByte(mb, k, Gray)
        SetMemblockByte(mb, k+1, Gray)
        SetMemblockByte(mb, k+2, Gray)
    next k
    CreateImageFromMemblock(img, mb)
    DeleteMemblock(mb)
endfunction

CreateSprite(2,2)
SetSpriteDepth(2,11)

SetWindowSize( 1024, 768, 0 )
SetVirtualResolution( 1024, 768 )


#Constant shr >>
#Constant shl <<
#Constant _AND_ &&
#Constant _OR_ ||

//Gray = 0.2126×Red + 0.7152×Green + 0.0722×Blue
#Constant kR 13932
#Constant kG 46872
#Constant kB 4731
#Constant _BYTE_MASK_ 0x000000FF
#Constant _ALPHA_MASK_ 0xFF000000

LoadImage(1,"youimage.png") 
 

CreateSprite(1,1)
MakeGreyscale(1)






do
    sync()  
loop
 
function MakeGreyscale(spr)

    img = GetSpriteImageID(spr)
    mb = CreateMemblockFromImage(img)
    size = GetMemblockSize(mb)
    



    for k = 12 to size-4 step 4
        C = GetMemblockInt(mb, k)
        Gray = C _AND_ _ALPHA_MASK_
        r = (C _AND_ _BYTE_MASK_) * kB
        C = C Shr 8
        g = (C _AND_ _BYTE_MASK_) * kG
        C = C Shr 8
        b = (C _AND_ _BYTE_MASK_) * kR
        C = (r + g + b) Shr 16
        Gray = Gray _OR_ C
        Gray = Gray _OR_ (C Shl 8)
        Gray = Gray _OR_ (C Shl 16)
        SetMemblockInt(mb, k, Gray)
    next k
    CreateImageFromMemblock(img, mb)
    DeleteMemblock(mb)
endfunction