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very rough start to affine sprites

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Matthew Berry 2021-01-16 12:30:14 -08:00
parent 99ac277ca0
commit 480f4b181b
1 changed files with 25 additions and 10 deletions
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35
src/crab/ppu.cr
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@ -167,23 +167,38 @@ class PPU
end
def render_sprites(scanline : Slice(UInt16), row : Int, priority : Int) : Nil
# todo: need to touch all of this up at some point for affine sprites
base = 0x10000_u32
Slice(Sprite).new(@oam.to_unsafe.as(Sprite*), 128).each do |sprite|
sprites = Slice(Sprite).new(@oam.to_unsafe.as(Sprite*), 128)
sprites.each do |sprite|
next unless sprite.priority == priority
next if sprite.obj_shape == 3 # prohibited
# Treating these as signed integers to support wrapping. Note: Won't necessarily work for affine sprites. Thanks, Tonc.
x_coord, y_coord = (sprite.x_coord << 7).to_i16! >> 7, sprite.y_coord.to_i8!.to_i16!
width, height = SIZES[sprite.obj_shape][sprite.obj_size]
if sprite.affine
oam_affine_entry = sprite.attr1_bits_9_13
# signed 8.8 fixed-point numbers, need to shr 8
pa = sprites[oam_affine_entry * 4].aff_param.to_i32
pb = sprites[oam_affine_entry * 4 + 1].aff_param.to_i32
pc = sprites[oam_affine_entry * 4 + 2].aff_param.to_i32
pd = sprites[oam_affine_entry * 4 + 3].aff_param.to_i32
if sprite.attr0_bit_9 # double-size (rotated sprites won't clip unless scaled)
x_coord += width >> 1
y_coord += height >> 1
width <<= 1
height <<= 1
end
else # identity matrix if sprite isn't affine (shifted left 8 to match the 8.8 fixed-point)
pa, pb, pc, pd = 0x100, 0, 0, 0x100
end
if y_coord <= row < y_coord + height
sprite_y = row - y_coord
sprite_y = height - sprite_y - 1 if bit?(sprite.attr1, 13)
sprite_y = height - sprite_y - 1 if bit?(sprite.attr1, 13) && !sprite.affine
y = sprite_y & 7
x_min, x_max = x_coord, Math.min(240, x_coord + width)
(x_min...x_max).each_with_index do |col, sprite_x|
next if col < 0
(x_coord...x_coord + width).each_with_index do |col, sprite_x|
next unless 0 <= col < 240
next if scanline[col] > 0
sprite_x = width - sprite_x - 1 if bit?(sprite.attr1, 12)
# puts "#{sprite_x},#{sprite_y} #{pa},#{pb},#{pc},#{pd} #{row},#{col} #{sprite.affine}"
sprite_x = width - sprite_x - 1 if bit?(sprite.attr1, 12) && !sprite.affine
x = sprite_x & 7
tile_id = sprite.character_name
if sprite.color_mode # 8bpp
@ -353,7 +368,7 @@ SIZES = [
],
]
record Sprite, attr0 : UInt16, attr1 : UInt16, attr2 : UInt16, unused_space : UInt16 do
record Sprite, attr0 : UInt16, attr1 : UInt16, attr2 : UInt16, aff_param : Int16 do
# OBJ Attribute 0
def obj_shape
@ -376,7 +391,7 @@ record Sprite, attr0 : UInt16, attr1 : UInt16, attr2 : UInt16, unused_space : UI
bit?(attr0, 9)
end
def scaling_flag
def affine
bit?(attr0, 8)
end