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reworded sprites modes. thanks marshal!

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sejo 2021-09-28 14:53:56 -05:00
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src/uxn_tutorial_day_2.gmo
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@ -541,12 +541,20 @@ nice, isn't it?
we'll see now how to leverage the built-in support for "sprites" in the uxn screen device, in order to draw many pixels at once!
# drawing sprites
the varvara screen device allows us to use and draw tiles of 8x8 pixels, also called sprites.
there are two posible modes: 1bpp (1 bit per pixel), and 2bpp (2 bits per pixel).
1bpp tiles use two colors, and they are encoded using 8 bytes; using one bit per pixel means that we can only encode if that pixel is using one color, or the other.
2bpp tiles use four colors and they are encoded using 16 bytes; using two bits per pixel we can encode one color out of four.
we will be storing and accessing these tiles from the main memory.
# drawing 1bpp sprites
the varvara screen device allows us to use and draw tiles of 8x8 pixels (sprites), stored in the main memory.
these tiles can be either in a 1bpp (1 bit per pixel) format, 8 bytes in size, or in a 2bpp (2 bits per pixel) format, with a size of 16 bytes.
a 1bpp tile consists in a set of 8 bytes that encode the state of its 8x8 pixels.
each byte corresponds to a row of the tile, and each bit in a row corresponds to the state of a pixel from left to right: it can be either "on" (1) or "off" (0).
@ -815,7 +823,9 @@ i invite you to try using these sprites instead to explore how to draw them flip
# drawing 2bpp sprites
in 2bpp sprites, each pixel can have one of four possible states.
in 2bpp sprites each pixel can have one of four possible colors.
we can think that, in order to assign these colors, we will encode one out of four states in each of the pixels of the sprite.
each one of these states can be encoded with a combination of two bits. these states can be assigned different combination of the four system colors, by using appropriate values in the screen color byte.