/icon.Blend() problem

ID:142351
 
Jun 18 2008, 4:04 pm
Code:
map_to_icon
    proc
        GenerateState(x, y, z)
            var/list/pixels[1024]

            var
                pixel_x = x
                pixel_y = y
            
            for(var/a = 1, a <= 1024, a ++)
                pixels[a] = GenerateTurfColor(pixel_x, pixel_y, z)

                pixel_x += x_ratio
                if(pixel_x > (32 * x_ratio))
                    pixel_x = x

                    pixel_y += y_ratio

            var
                x_shift = 0
                y_shift = 0
    
                icon/state = new('Templates.dmi', "blank")

            for(var/a in pixels)
                var/icon/pixel = GeneratePixel(x_shift, y_shift, a)
                state.Blend(pixel, ICON_ADD)

                world << "\t\icon[pixel]"
                world << "\t\icon[state]\n"

                x_shift ++
                if(x_shift >= 32)
                    x_shift = 0

                    y_shift ++

            AddState(state)
            total_states ++

        GeneratePixel(x, y, rgb)
            var/icon/i = new('Templates.dmi', "pixel")

            i.Shift(EAST, x)
            i.Shift(NORTH, y)
            i.Blend(rgb, ICON_ADD)

            return i


Problem description:
Alright, the pixel is generated (I've made a 16x16 square, actually, to test), and its getting shifted and modified with the right color. Problem is, when I try to blend the icon with state, nothing happens. The modified pixel icon is output, but the state icon isn't.
Jun 18 2008, 4:28 pm
The problem here might be the fact that you're using the ICON_ADD function. ICON_ADD will compare (much like binary OR) the two pixels of each icon, and if the pixel in either icon is transparent, the result will be transparent.

I believe if you use the ICON_OR (which, contrary to the name, is like binary AND) function, you'll get the desired results.
Jun 18 2008, 4:30 pm
In response to Volte
Actually, that made me look back on my previous version of this. Turns out ICON_OVERLAY is what I used.
Jun 18 2008, 4:36 pm
I sense two problems with your code. Both are subtle.

Popisfizzy wrote:
Code:
>               if(pixel_x > (32 * x_ratio))
>                   pixel_x = x
> 
>                   pixel_y += y_ratio


In this snippet, you're checking if(pixel_x > (32 * x_ratio)). This would be fine if pixel_x started at 1, but it actually starts at x, so I believe you want to check if(pixel_x >= (x + 32*x_ratio)), if my math is correct.


>           for(var/a in pixels)
>               var/icon/pixel = GeneratePixel(x_shift, y_shift, a)
>               state.Blend(pixel, ICON_ADD)


The problem here is a simple misuse of the second argument to icon.Blend(). You want to use ICON_OVERLAY; instead, you're using ICON_ADD, which means that the transparent regions of the icons are ORed together, and if either is transparent on a given pixel (presumably, state will be, considering it comes from a blank state), the resulting pixel is transparent.

Edit: Rats, I started this post before Volte posted his, and he covered one of my two points before I managed to get it in. Cheater!