58 lines
2.5 KiB
Swift
58 lines
2.5 KiB
Swift
/**
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* Copyright (c) 2019 Razeware LLC
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* Notwithstanding the foregoing, you may not use, copy, modify, merge, publish,
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* distribute, sublicense, create a derivative work, and/or sell copies of the
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* Software in any work that is designed, intended, or marketed for pedagogical or
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* instructional purposes related to programming, coding, application development,
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* or information technology. Permission for such use, copying, modification,
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* merger, publication, distribution, sublicensing, creation of derivative works,
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* or sale is expressly withheld.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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import MetalKit
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struct Particle {
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var position: float2
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}
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struct Emitter {
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var particleBuffer: MTLBuffer!
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init(particleCount: Int, size: CGSize, device: MTLDevice) {
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let bufferSize = MemoryLayout<Particle>.stride * particleCount
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particleBuffer = device.makeBuffer(length: bufferSize)
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var pointer = particleBuffer.contents().bindMemory(to: Particle.self,
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capacity: particleCount)
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for _ in 0..<particleCount {
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let width = random(Int(size.width) / 2) + Float(size.width) / Float(4)
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let height = random(Int(size.height) / 2) + Float(size.height) / Float(4)
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let position = float2(width, height)
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pointer.pointee.position = position
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pointer = pointer.advanced(by: 1)
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}
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}
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func random(_ max: Int) -> Float {
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return Float.random(in: 0..<Float(max))
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}
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}
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