51 lines
1.7 KiB
Python
51 lines
1.7 KiB
Python
"""Camera module - manages zoom and pan for a 2D viewport."""
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import pygame as pg
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class Camera:
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"""2D camera with zoom and world/screen coordinate conversion.
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Attributes:
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zoom (float): Current zoom multiplier, clamped to [0.5, 4.0].
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offset (pg.math.Vector2): Top-left world position currently in view.
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"""
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def __init__(self):
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self.zoom = 2
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self.offset = pg.math.Vector2(0, 0)
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def world_to_screen(self, pos):
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"""Convert a world-space position to screen pixels."""
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return (
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int((pos[0] - self.offset.x) * self.zoom),
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int((pos[1] - self.offset.y) * self.zoom),
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)
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def screen_to_world(self, pos):
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"""Convert a screen pixel position to world-space coordinates."""
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return (
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pos[0] / self.zoom + self.offset.x,
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pos[1] / self.zoom + self.offset.y,
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)
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def move(self, dx, dy):
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"""Pan the camera by (dx, dy) in world-space units."""
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self.offset.x += dx
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self.offset.y += dy
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def change_zoom(self, amount):
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"""Adjust zoom by amount, clamped to [0.5, 4.0]."""
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self.zoom += amount
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self.zoom = max(0.5, min(self.zoom, 4.0))
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def zoom_offset(self, screen_pos, zoom_factor):
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"""Zoom toward screen_pos, keeping the world point under it stationary."""
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world_before = self.screen_to_world(screen_pos)
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self.change_zoom(zoom_factor)
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world_after = self.screen_to_world(screen_pos)
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# Compensate offset so the point under the cursor doesn't shift
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self.offset.x += world_before[0] - world_after[0]
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self.offset.y += world_before[1] - world_after[1]
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