73 lines
2.4 KiB
Nim
73 lines
2.4 KiB
Nim
# ponytail: grid accumulator replaces ring buffer; add temporal features when needed (step 3)
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import std/math
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const
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VPERP_BINS* = 17 # -8 to +8 inclusive (integer speed units)
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DIST_BINS* = 8 # distance bands
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DIST_BAND* = 125.0 # pixels per band
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type
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GridCell = object
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sumSin: float
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sumCos: float
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count: float
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LeadGrid* = object
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cells: array[VPERP_BINS * DIST_BINS, GridCell] # 17 × 8 = 136 cells
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const BULLET_SPEED = 14.0 # power 2 bullet speed in pixels/tick
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proc initLeadGrid*(): LeadGrid =
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for vBin in 0..<VPERP_BINS:
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for dBin in 0..<DIST_BINS:
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let vPerp = float(vBin) - 8.0
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let sinVal = clamp(vPerp / BULLET_SPEED, -1.0, 1.0)
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let offsetRad = arcsin(sinVal)
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let idx = vBin * DIST_BINS + dBin
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result.cells[idx].sumSin = 0.1 * sin(offsetRad)
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result.cells[idx].sumCos = 0.1 * cos(offsetRad)
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result.cells[idx].count = 0.1
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proc cellIndex(vPerp: float, distance: float): int {.inline.} =
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let vBin = clamp(int(vPerp + 8.5), 0, VPERP_BINS - 1)
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let dBin = clamp(int(distance / DIST_BAND), 0, DIST_BINS - 1)
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result = vBin * DIST_BINS + dBin
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proc forward*(grid: var LeadGrid, vPerp, distance: float): float =
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## Returns circular mean offset in degrees, or -999.0 when no data.
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let idx = cellIndex(vPerp, distance)
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let vBin = clamp(int(vPerp + 8.5), 0, VPERP_BINS - 1)
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let dBin = clamp(int(distance / DIST_BAND), 0, DIST_BINS - 1)
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# Accumulate weighted contributions: direct cell (w=1), cardinal neighbors (w=0.5), diagonals (w=0.25)
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var sinSum = 0.0
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var cosSum = 0.0
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var totalW = 0.0
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for dv in -1 .. 1:
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for dd in -1 .. 1:
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let vb = vBin + dv
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let db = dBin + dd
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if vb < 0 or vb >= VPERP_BINS or db < 0 or db >= DIST_BINS: continue
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let c = grid.cells[vb * DIST_BINS + db]
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if c.count < 0.001: continue
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let w = if dv == 0 and dd == 0: 1.0
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elif dv == 0 or dd == 0: 0.5
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else: 0.25
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sinSum += w * c.sumSin / c.count
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cosSum += w * c.sumCos / c.count
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totalW += w
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if totalW == 0.0:
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return -999.0
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result = radToDeg(arctan2(sinSum, cosSum))
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proc learn*(grid: var LeadGrid, vPerp, distance, correctOffset: float) =
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let idx = cellIndex(vPerp, distance)
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grid.cells[idx].sumSin += sin(degToRad(correctOffset))
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grid.cells[idx].sumCos += cos(degToRad(correctOffset))
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grid.cells[idx].count += 1.0
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proc totalCount*(grid: LeadGrid): float =
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for c in grid.cells:
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result += c.count
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