28 lines
1.4 KiB
GDScript3
28 lines
1.4 KiB
GDScript3
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extends ColorRect
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# Feeds the starfield shader the camera's position split into a CELL INDEX
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# plus a fraction within that cell, rather than a raw world position.
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#
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# Why: the fleet routinely reaches world coordinates in the tens of
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# thousands. Handing those straight to the shader forces every downstream
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# calculation (the division by cell_size, floor/fract, and especially the
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# hash's internal multiplies) to work at large magnitudes, where a mobile
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# GPU's float precision starts to break down - and no precision qualifier
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# can fix that, since `highp` widens the type but the magnitudes stay huge.
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# GDScript computes in double precision, so doing the split here and passing
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# only small numbers (cell indices in the hundreds, fractions in [0,1])
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# keeps the shader's arithmetic in a range it can represent exactly.
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@onready var camera: Camera2D = get_node("../../Camera2D")
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func _process(_delta: float) -> void:
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var viewport_size: Vector2 = get_viewport_rect().size
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var cell_size: float = material.get_shader_parameter("cell_size")
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var p: Vector2 = camera.global_position / cell_size
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var cell: Vector2 = Vector2(floor(p.x), floor(p.y))
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material.set_shader_parameter("camera_cell", cell)
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material.set_shader_parameter("camera_frac", p - cell)
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material.set_shader_parameter("camera_zoom", 1.0 / camera.zoom.x)
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material.set_shader_parameter("viewport_size", viewport_size)
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