Sprites, default transparency colors

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Darth Randal

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Posted: 7th Mar 2005 08:24

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i recently started workin 2d games, and i've hit something of a rut. See i was working on putting some bmps and title screens together, and at this one point where I have a bmp and a sprite onscreen, everything i have colored black on the sprite shows as transparent. is there some way to redirect this effect to another color? heres the problem code if anyone cares to check it out.

+ Code Snippet

ink 0,1
color backdrop rgb(0,0,1)
hide mouse
load bitmap "splash.bmp"
wait 3000
cls


load bitmap "Tank.bmp",2
get image 2,0,0,60,60
sprite 1,100,100,2
delete bitmap 2
load bitmap "grass.bmp"

wait 5000
end

Thanks

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pizzaman

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Posted: 7th Mar 2005 09:09

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turn the last parameter of the set sprite command to 0.
For example

set sprite SpriteNum, Backsave, 0

or before you load the image for the sprite use set image color key to some other colour than black (this command is only for DBP)

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Darth Randal

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Posted: 8th Mar 2005 03:29

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is there any way to set the transparency color in dbc?

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pizzaman

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Posted: 9th Mar 2005 22:51 Edited at: 9th Mar 2005 23:02

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No unfortunately, however in a painting package you can set transparency to your image if you save to a png file. Then you should have transparency in your image in DB in the right places - i think, I haven't used DB in ages (I've got DBP).

The other thing I can think of is if you the expansion pack (or versions greater than 1.2 - i think it is), load your image into a memblock (note your screen resolution has to be in 32 bit mode), and scan the values for a certain colour value, and if you find that value then set the transparency for that value to 255. Then make the memblock to an image and you should have your home made set color key command.

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Robot

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Posted: 15th Mar 2005 03:04 Edited at: 15th Mar 2005 03:06

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wow pizzaman do you have an example of how to do that mamblock one?

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pizzaman

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Posted: 15th Mar 2005 10:55

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Hi Robot

Just made this for you, only took a minute. Below is the function:

+ Code Snippet

`note: you must be in 32 bit colour mode.
function ChangeColourKey(InputNum,OutputImage,Colour)

   make memblock from image 256,InputNum

   for index = 12 to get memblock size(256) - 1 step 4
      if memblock dword(256,index) = Colour then write memblock byte 256,index + 3,0
   next index

   make image from memblock OutputImage,256
   delete memblock 256

endfunction

and this is a sample program using it

+ Code Snippet

cls rgb(255,255,255)
ink rgb(255,0,0),0

box 20,20,108,108
get image 1,0,0,128,128

ChangeColourKey(1,2,rgb(255,0,0))

cls rgb(0,255,0)
paste image 1,0,0,1
paste image 2,300,0,1

sync
wait key

delete image 1
delete image 2

end


`note: you must be in 32 bit colour mode.
function ChangeColourKey(InputNum,OutputImage,Colour)

   make memblock from image 256,InputNum

   for index = 12 to get memblock size(256) - 1 step 4
      if memblock dword(256,index) = Colour then write memblock byte 256,index + 3,0
   next index

   make image from memblock OutputImage,256
   delete memblock 256

endfunction

There is one problem using this, any black parts (rgb(0,0,0)) are still counted as transparent in DBC, unfortunately. The only way around that is to use a colour close to black such as rgb(1,0,0), etc for the black parts.

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Pincho Paxton

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Posted: 15th Mar 2005 17:14

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The best way is to use the magic wand on the background, then invert the selection, then adjust the brightness of the image by a very small amount to make the black move from 000 to 111, or 222, or 333. It is hard to tell the difference.

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Robot

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Posted: 17th Mar 2005 02:59 Edited at: 17th Mar 2005 03:15

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Thank you so much pizza man that is a great example

would you be able to change black by adding this in the function?

+ Code Snippet

if memblock dword(256,index) = rgb(0,0,0) then write memblock byte 256,index + 3,1

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pizzaman

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Posted: 17th Mar 2005 11:13 Edited at: 17th Mar 2005 11:18

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Hi Robot

I had tried to make the black opaque once before using a code snippet nearly identicle to yours, however it did not work. Just seeing that code snippet you posted got me thinking why it didn't work. I investigated it and now have a colour key command for all DBC users - Horay. In other words you can now have perfect black, rgb(0,0,0) displayed on screen while making another colour transparent.

These are the new altered functions

`note: you must be in 32 bit colour mode to use these functions.
function ChangeColourKey(InputImage,OutputImage,Colour,ChangeBlack)
   make memblock from image 256,InputImage

if ChangeBlack = 0

for index = 12 to get memblock size(256) - 1 step 4
         if memblock dword(256,index) = Colour then write memblock byte 256,index + 3,0
      next index

else

for index = 12 to get memblock size(256) - 1 step 4
         if memblock dword(256,index) = 0      then write memblock byte 256,index + 3,255
         if memblock dword(256,index) = Colour then write memblock byte 256,index + 3,0
      next index

endif

make image from memblock OutputImage,256
   delete memblock 256
endfunction

function OpaqueBlack(InputImage,OutputImage)
   make memblock from image 256,InputImage

for index = 12 to get memblock size(256) - 1 step 4
      if memblock dword(256,index) = 0 then write memblock byte 256,index + 3,255
   next index

make image from memblock OutputImage,256
   delete memblock 256
endfunction

+ Code Snippet

`note: you must be in 32 bit colour mode to use these functions.
function ChangeColourKey(InputImage,OutputImage,Colour,ChangeBlack)
   make memblock from image 256,InputImage

   if ChangeBlack = 0

      for index = 12 to get memblock size(256) - 1 step 4
         if memblock dword(256,index) = Colour then write memblock byte 256,index + 3,0
      next index

   else

      for index = 12 to get memblock size(256) - 1 step 4
         if memblock dword(256,index) = 0      then write memblock byte 256,index + 3,255
         if memblock dword(256,index) = Colour then write memblock byte 256,index + 3,0
      next index

   endif

   make image from memblock OutputImage,256
   delete memblock 256
endfunction

function OpaqueBlack(InputImage,OutputImage)
   make memblock from image 256,InputImage

   for index = 12 to get memblock size(256) - 1 step 4
      if memblock dword(256,index) = 0 then write memblock byte 256,index + 3,255
   next index

   make image from memblock OutputImage,256
   delete memblock 256
endfunction

Set the ChangeBlack to anything other than 0 to make black not transparent. I also included a function to just set black opaque.

Here is the example program updated

`make a box that has a white border, then an inner black border
`then a red box in the middle
cls rgb(255,255,255)
ink rgb(0,0,0),rgb(0,0,0)
box 20,20,108,108
ink rgb(255,0,0),rgb(0,0,0)
box 40,40,88,88
get image 1,0,0,128,128,1
ink rgb(255,255,255),rgb(0,0,0)

cls rgb(0,0,255)
paste image 1,0,0,1

OpaqueBlack(1,1)
ChangeColourKey(1,2,rgb(255,0,0),1)

paste image 1,0,150,1
paste image 2,0,300,1

text 150,0,"This is what happens to a normal image with black in"
text 150,20,"it with transparency on."
text 150,150,"This image has true black even though transparency"
text 150,170,"is on. This how the image looked when it was created."
text 150,300,"This image has true black while the red part is transparent."
text 150,450,"Press any key to exit."
sync
wait key

delete image 1
delete image 2

end

`note: you must be in 32 bit colour mode to use these functions.
function ChangeColourKey(InputImage,OutputImage,Colour,ChangeBlack)
   make memblock from image 256,InputImage

if ChangeBlack = 0

for index = 12 to get memblock size(256) - 1 step 4
         if memblock dword(256,index) = Colour then write memblock byte 256,index + 3,0
      next index

else

for index = 12 to get memblock size(256) - 1 step 4
         if memblock dword(256,index) = 0      then write memblock byte 256,index + 3,255
         if memblock dword(256,index) = Colour then write memblock byte 256,index + 3,0
      next index

endif

make image from memblock OutputImage,256
   delete memblock 256
endfunction

function OpaqueBlack(InputImage,OutputImage)
   make memblock from image 256,InputImage

for index = 12 to get memblock size(256) - 1 step 4
      if memblock dword(256,index) = 0 then write memblock byte 256,index + 3,255
   next index

make image from memblock OutputImage,256
   delete memblock 256
endfunction

+ Code Snippet

`make a box that has a white border, then an inner black border
`then a red box in the middle
cls rgb(255,255,255)
ink rgb(0,0,0),rgb(0,0,0)
box 20,20,108,108
ink rgb(255,0,0),rgb(0,0,0)
box 40,40,88,88
get image 1,0,0,128,128,1
ink rgb(255,255,255),rgb(0,0,0)

cls rgb(0,0,255)
paste image 1,0,0,1

OpaqueBlack(1,1)
ChangeColourKey(1,2,rgb(255,0,0),1)

paste image 1,0,150,1
paste image 2,0,300,1

text 150,0,"This is what happens to a normal image with black in"
text 150,20,"it with transparency on."
text 150,150,"This image has true black even though transparency"
text 150,170,"is on. This how the image looked when it was created."
text 150,300,"This image has true black while the red part is transparent."
text 150,450,"Press any key to exit."
sync
wait key

delete image 1
delete image 2

end


`note: you must be in 32 bit colour mode to use these functions.
function ChangeColourKey(InputImage,OutputImage,Colour,ChangeBlack)
   make memblock from image 256,InputImage

   if ChangeBlack = 0

      for index = 12 to get memblock size(256) - 1 step 4
         if memblock dword(256,index) = Colour then write memblock byte 256,index + 3,0
      next index

   else

      for index = 12 to get memblock size(256) - 1 step 4
         if memblock dword(256,index) = 0      then write memblock byte 256,index + 3,255
         if memblock dword(256,index) = Colour then write memblock byte 256,index + 3,0
      next index

   endif

   make image from memblock OutputImage,256
   delete memblock 256
endfunction



function OpaqueBlack(InputImage,OutputImage)
   make memblock from image 256,InputImage

   for index = 12 to get memblock size(256) - 1 step 4
      if memblock dword(256,index) = 0 then write memblock byte 256,index + 3,255
   next index

   make image from memblock OutputImage,256
   delete memblock 256
endfunction

Note that I've only tested this in DBP so could you tell me if it works (I think it should). Anyway hope it helps you.

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Robot

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Posted: 17th Mar 2005 15:09

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I edited your origional code a bit by having to change write byte to dword otherwise it did not change the picture and added in the opaque black thing
also changed memblock number as it only goes up to 255 in dbc

+ Code Snippet

set display mode 640,480,32
cls rgb(255,255,255)
ink rgb(255,0,0),0

box 20,20,108,108
ink rgb(0,0,0),0
box 30,30,98,98
get image 1,0,0,128,128

ChangeColourKey(1,2,rgb(255,0,0))

cls rgb(0,255,0)

sprite 1,0,0,1
sprite 2,300,0,2

sync
wait key

delete image 1
delete image 2

end


`note: you must be in 32 bit colour mode.
function ChangeColourKey(InputNum,OutputImage,Colour)

   make memblock from image 1,InputNum

   for index = 12 to get memblock size(1) - 1 step 4
      if memblock dword(1,index) = rgb(0,0,0) then write memblock dword 1,index,rgb(1,1,1)
      if memblock dword(1,index) = Colour then write memblock dword 1,index,0
   next index

   make image from memblock OutputImage,1
   delete memblock 1

endfunction

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2D All the way! / Sprites, default transparency colors