Decode boxes, rearrange some code

This commit is contained in:
Jeremy Penner 2023-12-22 16:54:40 -05:00
parent 352fb0ddd0
commit 7e3d096d47

221
index.js
View file

@ -1,3 +1,5 @@
const LE = true // little-endian
const readBinary = async (url) => {
const response = await fetch(url)
if (!response.ok) {
@ -7,92 +9,6 @@ const readBinary = async (url) => {
return new DataView(await response.arrayBuffer())
}
const decodeHowHeld = (byte) => {
const heldVal = byte & 0xc0
if (heldVal == 0) {
return "swing"
} else if (heldVal == 0x40) {
return "out"
} else if (heldVal == 0x80) {
return "both"
} else {
return "at_side"
}
}
const LE = true // little-endian
const decodeCelType = (byte) => {
const typeVal = byte & 0xc0
if (typeVal == 0x00) {
if ((byte & 0x20) == 0) {
return "bitmap"
} else {
return "text"
}
} else if (typeVal == 0x40) {
return "trap"
} else if (typeVal == 0x80) {
return "box"
} else {
return "circle"
}
}
const emptyBitmap = (w, h) => {
const bitmap = []
for (let y = 0; y < h; y ++) {
const scanline = []
for (let x = 0; x < w; x ++) {
scanline.push(0)
scanline.push(0)
scanline.push(0)
scanline.push(0)
}
bitmap.push(scanline)
}
return bitmap
}
const celDecoder = {}
celDecoder.bitmap = (data, cel) => {
const bitmap = emptyBitmap(cel.width, cel.height)
let ibmp = 0
const end = cel.width * cel.height
const putByte = (byte) => {
const x = Math.floor(ibmp / cel.height) * 4
const y = (cel.height - (ibmp % cel.height)) - 1
bitmap[y][x] = (byte & 0xc0) >> 6
bitmap[y][x + 1] = (byte & 0x3c) >> 4
bitmap[y][x + 2] = (byte & 0x0c) >> 2
bitmap[y][x + 3] = (byte & 0x03)
ibmp ++
}
let i = 6
while (ibmp < end) {
const byte = data.getUint8(i)
i ++
if (byte == 0) {
const count = data.getUint8(i)
i ++
if ((count & 0x80) == 0) {
const val = data.getUint8(i)
i ++
for (let repeat = 0; repeat < count; repeat ++) {
putByte(val)
}
} else {
// transparent run
for (let repeat = 0; repeat < (count & 0x7f); repeat ++) {
putByte(0)
}
}
} else {
putByte(byte)
}
}
cel.bitmap = bitmap
}
const makeCanvas = (w, h) => {
const canvas = document.createElement("canvas")
canvas.width = w
@ -100,7 +16,7 @@ const makeCanvas = (w, h) => {
return canvas
}
const drawBitmap = (bitmap) => {
const canvasFromBitmap = (bitmap) => {
const h = bitmap.length
const w = bitmap[0].length * 2
const canvas = makeCanvas(w, h)
@ -141,6 +57,128 @@ const drawBitmap = (bitmap) => {
return canvas
}
// JS bitmap format: array of scanlines, each scanline being an array of numbers from 0-3
const emptyBitmap = (w, h, color = 0) => {
const bitmap = []
for (let y = 0; y < h; y ++) {
const scanline = []
for (let x = 0; x < w; x ++) {
scanline.push(color)
scanline.push(color)
scanline.push(color)
scanline.push(color)
}
bitmap.push(scanline)
}
return bitmap
}
const drawByte = (bitmap, x, y, byte) => {
bitmap[y][x] = (byte & 0xc0) >> 6
bitmap[y][x + 1] = (byte & 0x3c) >> 4
bitmap[y][x + 2] = (byte & 0x0c) >> 2
bitmap[y][x + 3] = (byte & 0x03)
}
// Prop decoding functions
const decodeHowHeld = (byte) => {
const heldVal = byte & 0xc0
if (heldVal == 0) {
return "swing"
} else if (heldVal == 0x40) {
return "out"
} else if (heldVal == 0x80) {
return "both"
} else {
return "at_side"
}
}
const decodeCelType = (byte) => {
const typeVal = byte & 0xc0
if (typeVal == 0x00) {
if ((byte & 0x20) == 0) {
return "bitmap"
} else {
return "text"
}
} else if (typeVal == 0x40) {
return "trap"
} else if (typeVal == 0x80) {
return "box"
} else {
return "circle"
}
}
const celDecoder = {}
celDecoder.bitmap = (data, cel) => {
// bitmap cells are RLE-encoded vertical strips of bytes. Decoding starts from the bottom-left
// and proceeds upwards until the top of the bitmap is hit; then then next vertical strip is decoded.
// Each byte describes four 2-bit pixels.
const bitmap = emptyBitmap(cel.width, cel.height)
let ibmp = 0
const end = cel.width * cel.height
const putByte = (byte) => {
const x = Math.floor(ibmp / cel.height) * 4
const y = (cel.height - (ibmp % cel.height)) - 1
drawByte(bitmap, x, y, byte)
ibmp ++
}
let i = 6
while (ibmp < end) {
const byte = data.getUint8(i)
i ++
if (byte == 0) {
// A zero byte denotes the start of a run of identical bytes. The second
// byte denotes the number of repetitions.
const count = data.getUint8(i)
i ++
if ((count & 0x80) == 0) {
// if the high bit of the count is not set, we read a third byte to
// determine the byte to repeat.
const val = data.getUint8(i)
i ++
for (let repeat = 0; repeat < count; repeat ++) {
putByte(val)
}
} else {
// if the high bit of the count is set, the lower 7 bits are used as
// the count, and a fully transparent byte is repeated.
for (let repeat = 0; repeat < (count & 0x7f); repeat ++) {
putByte(0)
}
}
} else {
// non-zero bytes are raw bitmap data
putByte(byte)
}
}
cel.bitmap = bitmap
}
celDecoder.box = (data, cel) => {
const bitmap = emptyBitmap(cel.width, cel.height)
cel.borderLR = (data.getUint8(0) & 0x20) != 0
cel.borderTB = (data.getUint8(0) & 0x10) != 0
cel.pattern = data.getUint8(6)
for (let y = 0; y < cel.height; y ++) {
for (let x = 0; x < cel.width; x ++) {
if (cel.borderTB && (y == 0 || y == (cel.height - 1))) {
drawByte(bitmap, x * 4, y, 0xaa)
} else {
drawByte(bitmap, x * 4, y, cel.pattern)
}
}
if (cel.borderLR) {
const line = bitmap[y]
line[0] = 2
line[line.length - 1] = 2
}
}
cel.bitmap = bitmap
}
const decodeCel = (data, changesColorRam) => {
const cel = {
data: data,
@ -158,7 +196,7 @@ const decodeCel = (data, changesColorRam) => {
celDecoder[cel.type](data, cel)
}
if (cel.bitmap) {
cel.image = drawBitmap(cel.bitmap).toDataURL()
cel.canvas = canvasFromBitmap(cel.bitmap)
}
return cel
}
@ -232,6 +270,8 @@ const decodeProp = (data) => {
// We could also potentially assume that this structure always follows the header (or the
// "container" XY array, if one exists), as that seems to be consistently be the case with all
// the props in the Habitat source tree.
// It's possible for there to be no frames, which is represented by an offset of 0 (no_animation)
if (graphicStateOff != 0) {
for (let frameOff = graphicStateOff; ; frameOff ++) {
const frame = decodeFrame(data.getUint8(frameOff), stateCount)
if (!frame) {
@ -239,6 +279,7 @@ const decodeProp = (data) => {
}
prop.frames.push(frame)
}
}
for (let celOffsetOff = celOffsetsOff; allCelsMask != 0; celOffsetOff += 2) {
const icel = prop.cels.length
const celbit = 0x80 >> icel
@ -251,9 +292,9 @@ const decodeProp = (data) => {
const showCels = (prop) => {
const container = document.getElementById("cels")
for (const cel of prop.cels) {
if (cel.image) {
if (cel.canvas) {
const img = document.createElement("img")
img.src = cel.image
img.src = cel.canvas.toDataURL()
img.width = cel.width * 4 * 2 * 3
img.height = cel.height * 3
img.style.imageRendering = "pixelated"