├── .gitignore
├── LICENSE.txt
├── README.md
├── RainGenerator.xcodeproj
    ├── project.pbxproj
    └── project.xcworkspace
    │   └── contents.xcworkspacedata
└── RainGenerator
    ├── Assets.xcassets
        ├── AccentColor.colorset
        │   └── Contents.json
        ├── AppIcon.appiconset
        │   └── Contents.json
        └── Contents.json
    ├── AudioEngine.swift
    ├── ContentView.swift
    ├── Preview Content
        └── Preview Assets.xcassets
        │   └── Contents.json
    ├── RainGenerator.entitlements
    └── RainGeneratorApp.swift


/.gitignore:
--------------------------------------------------------------------------------
 1 | .DS_Store
 2 | project.xcworkspace/
 3 | *.xcscmblueprint
 4 | xcuserdata/
 5 | .build
 6 | Package.pins
 7 | Package.resolved
 8 | Packages/
 9 | .swiftpm
10 | buildServer.json


--------------------------------------------------------------------------------
/LICENSE.txt:
--------------------------------------------------------------------------------
 1 | ISC License
 2 | 
 3 | Copyright © 2024 Matt Gallagher ( https://cocoawithlove.com ). All rights reserved.
 4 | 
 5 | Permission to use, copy, modify, and/or distribute this software for any
 6 | purpose with or without fee is hereby granted, provided that the above
 7 | copyright notice and this permission notice appear in all copies.
 8 | 
 9 | THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 | WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 | MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
12 | SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 | WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 | ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR
15 | IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.


--------------------------------------------------------------------------------
/README.md:
--------------------------------------------------------------------------------
1 | # RainGenerator
2 | 
3 | A basic raindrop and noise synthesizer, written in Swift using AVAudioGenerator and SwiftUI.
4 | 
5 | Read the associated article on Cocoa with Love: [Using Copilot to write a raindrop audio synthesizer using AVAudioEngine](https://www.cocoawithlove.com/blog/copilot-raindrop-generator.html)
6 | 
7 | This project was inspired by https://github.com/747745124/Raindrop-Generator
8 | 


--------------------------------------------------------------------------------
/RainGenerator.xcodeproj/project.pbxproj:
--------------------------------------------------------------------------------
  1 | // !$*UTF8*$!
  2 | {
  3 | 	archiveVersion = 1;
  4 | 	classes = {
  5 | 	};
  6 | 	objectVersion = 77;
  7 | 	objects = {
  8 | 
  9 | /* Begin PBXFileReference section */
 10 | 		C90227232CFC3E2400E5BD04 /* RainGenerator.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = RainGenerator.app; sourceTree = BUILT_PRODUCTS_DIR; };
 11 | /* End PBXFileReference section */
 12 | 
 13 | /* Begin PBXFileSystemSynchronizedRootGroup section */
 14 | 		C90227252CFC3E2400E5BD04 /* RainGenerator */ = {
 15 | 			isa = PBXFileSystemSynchronizedRootGroup;
 16 | 			path = RainGenerator;
 17 | 			sourceTree = "<group>";
 18 | 		};
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 26 | 			);
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 33 | 			isa = PBXGroup;
 34 | 			children = (
 35 | 				C90227252CFC3E2400E5BD04 /* RainGenerator */,
 36 | 				C90227242CFC3E2400E5BD04 /* Products */,
 37 | 			);
 38 | 			sourceTree = "<group>";
 39 | 		};
 40 | 		C90227242CFC3E2400E5BD04 /* Products */ = {
 41 | 			isa = PBXGroup;
 42 | 			children = (
 43 | 				C90227232CFC3E2400E5BD04 /* RainGenerator.app */,
 44 | 			);
 45 | 			name = Products;
 46 | 			sourceTree = "<group>";
 47 | 		};
 48 | /* End PBXGroup section */
 49 | 
 50 | /* Begin PBXNativeTarget section */
 51 | 		C90227222CFC3E2400E5BD04 /* RainGenerator */ = {
 52 | 			isa = PBXNativeTarget;
 53 | 			buildConfigurationList = C90227322CFC3E2500E5BD04 /* Build configuration list for PBXNativeTarget "RainGenerator" */;
 54 | 			buildPhases = (
 55 | 				C902271F2CFC3E2400E5BD04 /* Sources */,
 56 | 				C90227202CFC3E2400E5BD04 /* Frameworks */,
 57 | 				C90227212CFC3E2400E5BD04 /* Resources */,
 58 | 			);
 59 | 			buildRules = (
 60 | 			);
 61 | 			dependencies = (
 62 | 			);
 63 | 			fileSystemSynchronizedGroups = (
 64 | 				C90227252CFC3E2400E5BD04 /* RainGenerator */,
 65 | 			);
 66 | 			name = RainGenerator;
 67 | 			packageProductDependencies = (
 68 | 			);
 69 | 			productName = RainGenerator;
 70 | 			productReference = C90227232CFC3E2400E5BD04 /* RainGenerator.app */;
 71 | 			productType = "com.apple.product-type.application";
 72 | 		};
 73 | /* End PBXNativeTarget section */
 74 | 
 75 | /* Begin PBXProject section */
 76 | 		C902271B2CFC3E2300E5BD04 /* Project object */ = {
 77 | 			isa = PBXProject;
 78 | 			attributes = {
 79 | 				BuildIndependentTargetsInParallel = 1;
 80 | 				LastSwiftUpdateCheck = 1610;
 81 | 				LastUpgradeCheck = 1610;
 82 | 				TargetAttributes = {
 83 | 					C90227222CFC3E2400E5BD04 = {
 84 | 						CreatedOnToolsVersion = 16.1;
 85 | 					};
 86 | 				};
 87 | 			};
 88 | 			buildConfigurationList = C902271E2CFC3E2300E5BD04 /* Build configuration list for PBXProject "RainGenerator" */;
 89 | 			developmentRegion = en;
 90 | 			hasScannedForEncodings = 0;
 91 | 			knownRegions = (
 92 | 				en,
 93 | 				Base,
 94 | 			);
 95 | 			mainGroup = C902271A2CFC3E2300E5BD04;
 96 | 			minimizedProjectReferenceProxies = 1;
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 98 | 			productRefGroup = C90227242CFC3E2400E5BD04 /* Products */;
 99 | 			projectDirPath = "";
100 | 			projectRoot = "";
101 | 			targets = (
102 | 				C90227222CFC3E2400E5BD04 /* RainGenerator */,
103 | 			);
104 | 		};
105 | /* End PBXProject section */
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107 | /* Begin PBXResourcesBuildPhase section */
108 | 		C90227212CFC3E2400E5BD04 /* Resources */ = {
109 | 			isa = PBXResourcesBuildPhase;
110 | 			buildActionMask = 2147483647;
111 | 			files = (
112 | 			);
113 | 			runOnlyForDeploymentPostprocessing = 0;
114 | 		};
115 | /* End PBXResourcesBuildPhase section */
116 | 
117 | /* Begin PBXSourcesBuildPhase section */
118 | 		C902271F2CFC3E2400E5BD04 /* Sources */ = {
119 | 			isa = PBXSourcesBuildPhase;
120 | 			buildActionMask = 2147483647;
121 | 			files = (
122 | 			);
123 | 			runOnlyForDeploymentPostprocessing = 0;
124 | 		};
125 | /* End PBXSourcesBuildPhase section */
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127 | /* Begin XCBuildConfiguration section */
128 | 		C90227302CFC3E2500E5BD04 /* Debug */ = {
129 | 			isa = XCBuildConfiguration;
130 | 			buildSettings = {
131 | 				ALWAYS_SEARCH_USER_PATHS = NO;
132 | 				ASSETCATALOG_COMPILER_GENERATE_SWIFT_ASSET_SYMBOL_EXTENSIONS = YES;
133 | 				CLANG_ANALYZER_NONNULL = YES;
134 | 				CLANG_ANALYZER_NUMBER_OBJECT_CONVERSION = YES_AGGRESSIVE;
135 | 				CLANG_CXX_LANGUAGE_STANDARD = "gnu++20";
136 | 				CLANG_ENABLE_MODULES = YES;
137 | 				CLANG_ENABLE_OBJC_ARC = YES;
138 | 				CLANG_ENABLE_OBJC_WEAK = YES;
139 | 				CLANG_WARN_BLOCK_CAPTURE_AUTORELEASING = YES;
140 | 				CLANG_WARN_BOOL_CONVERSION = YES;
141 | 				CLANG_WARN_COMMA = YES;
142 | 				CLANG_WARN_CONSTANT_CONVERSION = YES;
143 | 				CLANG_WARN_DEPRECATED_OBJC_IMPLEMENTATIONS = YES;
144 | 				CLANG_WARN_DIRECT_OBJC_ISA_USAGE = YES_ERROR;
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149 | 				CLANG_WARN_INT_CONVERSION = YES;
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151 | 				CLANG_WARN_OBJC_IMPLICIT_RETAIN_SELF = YES;
152 | 				CLANG_WARN_OBJC_LITERAL_CONVERSION = YES;
153 | 				CLANG_WARN_OBJC_ROOT_CLASS = YES_ERROR;
154 | 				CLANG_WARN_QUOTED_INCLUDE_IN_FRAMEWORK_HEADER = YES;
155 | 				CLANG_WARN_RANGE_LOOP_ANALYSIS = YES;
156 | 				CLANG_WARN_STRICT_PROTOTYPES = YES;
157 | 				CLANG_WARN_SUSPICIOUS_MOVE = YES;
158 | 				CLANG_WARN_UNGUARDED_AVAILABILITY = YES_AGGRESSIVE;
159 | 				CLANG_WARN_UNREACHABLE_CODE = YES;
160 | 				CLANG_WARN__DUPLICATE_METHOD_MATCH = YES;
161 | 				COPY_PHASE_STRIP = NO;
162 | 				DEBUG_INFORMATION_FORMAT = dwarf;
163 | 				ENABLE_STRICT_OBJC_MSGSEND = YES;
164 | 				ENABLE_TESTABILITY = YES;
165 | 				ENABLE_USER_SCRIPT_SANDBOXING = YES;
166 | 				GCC_C_LANGUAGE_STANDARD = gnu17;
167 | 				GCC_DYNAMIC_NO_PIC = NO;
168 | 				GCC_NO_COMMON_BLOCKS = YES;
169 | 				GCC_OPTIMIZATION_LEVEL = 0;
170 | 				GCC_PREPROCESSOR_DEFINITIONS = (
171 | 					"DEBUG=1",
172 | 					"$(inherited)",
173 | 				);
174 | 				GCC_WARN_64_TO_32_BIT_CONVERSION = YES;
175 | 				GCC_WARN_ABOUT_RETURN_TYPE = YES_ERROR;
176 | 				GCC_WARN_UNDECLARED_SELECTOR = YES;
177 | 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
178 | 				GCC_WARN_UNUSED_FUNCTION = YES;
179 | 				GCC_WARN_UNUSED_VARIABLE = YES;
180 | 				LOCALIZATION_PREFERS_STRING_CATALOGS = YES;
181 | 				MACOSX_DEPLOYMENT_TARGET = 15.1;
182 | 				MTL_ENABLE_DEBUG_INFO = INCLUDE_SOURCE;
183 | 				MTL_FAST_MATH = YES;
184 | 				ONLY_ACTIVE_ARCH = YES;
185 | 				SDKROOT = macosx;
186 | 				SWIFT_ACTIVE_COMPILATION_CONDITIONS = "DEBUG $(inherited)";
187 | 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
188 | 			};
189 | 			name = Debug;
190 | 		};
191 | 		C90227312CFC3E2500E5BD04 /* Release */ = {
192 | 			isa = XCBuildConfiguration;
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197 | 				CLANG_ANALYZER_NUMBER_OBJECT_CONVERSION = YES_AGGRESSIVE;
198 | 				CLANG_CXX_LANGUAGE_STANDARD = "gnu++20";
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205 | 				CLANG_WARN_CONSTANT_CONVERSION = YES;
206 | 				CLANG_WARN_DEPRECATED_OBJC_IMPLEMENTATIONS = YES;
207 | 				CLANG_WARN_DIRECT_OBJC_ISA_USAGE = YES_ERROR;
208 | 				CLANG_WARN_DOCUMENTATION_COMMENTS = YES;
209 | 				CLANG_WARN_EMPTY_BODY = YES;
210 | 				CLANG_WARN_ENUM_CONVERSION = YES;
211 | 				CLANG_WARN_INFINITE_RECURSION = YES;
212 | 				CLANG_WARN_INT_CONVERSION = YES;
213 | 				CLANG_WARN_NON_LITERAL_NULL_CONVERSION = YES;
214 | 				CLANG_WARN_OBJC_IMPLICIT_RETAIN_SELF = YES;
215 | 				CLANG_WARN_OBJC_LITERAL_CONVERSION = YES;
216 | 				CLANG_WARN_OBJC_ROOT_CLASS = YES_ERROR;
217 | 				CLANG_WARN_QUOTED_INCLUDE_IN_FRAMEWORK_HEADER = YES;
218 | 				CLANG_WARN_RANGE_LOOP_ANALYSIS = YES;
219 | 				CLANG_WARN_STRICT_PROTOTYPES = YES;
220 | 				CLANG_WARN_SUSPICIOUS_MOVE = YES;
221 | 				CLANG_WARN_UNGUARDED_AVAILABILITY = YES_AGGRESSIVE;
222 | 				CLANG_WARN_UNREACHABLE_CODE = YES;
223 | 				CLANG_WARN__DUPLICATE_METHOD_MATCH = YES;
224 | 				COPY_PHASE_STRIP = NO;
225 | 				DEBUG_INFORMATION_FORMAT = "dwarf-with-dsym";
226 | 				ENABLE_NS_ASSERTIONS = NO;
227 | 				ENABLE_STRICT_OBJC_MSGSEND = YES;
228 | 				ENABLE_USER_SCRIPT_SANDBOXING = YES;
229 | 				GCC_C_LANGUAGE_STANDARD = gnu17;
230 | 				GCC_NO_COMMON_BLOCKS = YES;
231 | 				GCC_WARN_64_TO_32_BIT_CONVERSION = YES;
232 | 				GCC_WARN_ABOUT_RETURN_TYPE = YES_ERROR;
233 | 				GCC_WARN_UNDECLARED_SELECTOR = YES;
234 | 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
235 | 				GCC_WARN_UNUSED_FUNCTION = YES;
236 | 				GCC_WARN_UNUSED_VARIABLE = YES;
237 | 				LOCALIZATION_PREFERS_STRING_CATALOGS = YES;
238 | 				MACOSX_DEPLOYMENT_TARGET = 15.1;
239 | 				MTL_ENABLE_DEBUG_INFO = NO;
240 | 				MTL_FAST_MATH = YES;
241 | 				SDKROOT = macosx;
242 | 				SWIFT_COMPILATION_MODE = wholemodule;
243 | 			};
244 | 			name = Release;
245 | 		};
246 | 		C90227332CFC3E2500E5BD04 /* Debug */ = {
247 | 			isa = XCBuildConfiguration;
248 | 			buildSettings = {
249 | 				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
250 | 				ASSETCATALOG_COMPILER_GLOBAL_ACCENT_COLOR_NAME = AccentColor;
251 | 				CODE_SIGN_ENTITLEMENTS = RainGenerator/RainGenerator.entitlements;
252 | 				CODE_SIGN_STYLE = Automatic;
253 | 				COMBINE_HIDPI_IMAGES = YES;
254 | 				CURRENT_PROJECT_VERSION = 1;
255 | 				DEVELOPMENT_ASSET_PATHS = "\"RainGenerator/Preview Content\"";
256 | 				DEVELOPMENT_TEAM = S7YQ892G6G;
257 | 				ENABLE_HARDENED_RUNTIME = YES;
258 | 				ENABLE_PREVIEWS = YES;
259 | 				GENERATE_INFOPLIST_FILE = YES;
260 | 				INFOPLIST_KEY_NSHumanReadableCopyright = "";
261 | 				LD_RUNPATH_SEARCH_PATHS = (
262 | 					"$(inherited)",
263 | 					"@executable_path/../Frameworks",
264 | 				);
265 | 				MARKETING_VERSION = 1.0;
266 | 				PRODUCT_BUNDLE_IDENTIFIER = com.mattgallagher.RainGenerator;
267 | 				PRODUCT_NAME = "$(TARGET_NAME)";
268 | 				SWIFT_EMIT_LOC_STRINGS = YES;
269 | 				SWIFT_VERSION = 6.0;
270 | 			};
271 | 			name = Debug;
272 | 		};
273 | 		C90227342CFC3E2500E5BD04 /* Release */ = {
274 | 			isa = XCBuildConfiguration;
275 | 			buildSettings = {
276 | 				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
277 | 				ASSETCATALOG_COMPILER_GLOBAL_ACCENT_COLOR_NAME = AccentColor;
278 | 				CODE_SIGN_ENTITLEMENTS = RainGenerator/RainGenerator.entitlements;
279 | 				CODE_SIGN_STYLE = Automatic;
280 | 				COMBINE_HIDPI_IMAGES = YES;
281 | 				CURRENT_PROJECT_VERSION = 1;
282 | 				DEVELOPMENT_ASSET_PATHS = "\"RainGenerator/Preview Content\"";
283 | 				DEVELOPMENT_TEAM = S7YQ892G6G;
284 | 				ENABLE_HARDENED_RUNTIME = YES;
285 | 				ENABLE_PREVIEWS = YES;
286 | 				GENERATE_INFOPLIST_FILE = YES;
287 | 				INFOPLIST_KEY_NSHumanReadableCopyright = "";
288 | 				LD_RUNPATH_SEARCH_PATHS = (
289 | 					"$(inherited)",
290 | 					"@executable_path/../Frameworks",
291 | 				);
292 | 				MARKETING_VERSION = 1.0;
293 | 				PRODUCT_BUNDLE_IDENTIFIER = com.mattgallagher.RainGenerator;
294 | 				PRODUCT_NAME = "$(TARGET_NAME)";
295 | 				SWIFT_EMIT_LOC_STRINGS = YES;
296 | 				SWIFT_VERSION = 6.0;
297 | 			};
298 | 			name = Release;
299 | 		};
300 | /* End XCBuildConfiguration section */
301 | 
302 | /* Begin XCConfigurationList section */
303 | 		C902271E2CFC3E2300E5BD04 /* Build configuration list for PBXProject "RainGenerator" */ = {
304 | 			isa = XCConfigurationList;
305 | 			buildConfigurations = (
306 | 				C90227302CFC3E2500E5BD04 /* Debug */,
307 | 				C90227312CFC3E2500E5BD04 /* Release */,
308 | 			);
309 | 			defaultConfigurationIsVisible = 0;
310 | 			defaultConfigurationName = Release;
311 | 		};
312 | 		C90227322CFC3E2500E5BD04 /* Build configuration list for PBXNativeTarget "RainGenerator" */ = {
313 | 			isa = XCConfigurationList;
314 | 			buildConfigurations = (
315 | 				C90227332CFC3E2500E5BD04 /* Debug */,
316 | 				C90227342CFC3E2500E5BD04 /* Release */,
317 | 			);
318 | 			defaultConfigurationIsVisible = 0;
319 | 			defaultConfigurationName = Release;
320 | 		};
321 | /* End XCConfigurationList section */
322 | 	};
323 | 	rootObject = C902271B2CFC3E2300E5BD04 /* Project object */;
324 | }
325 | 


--------------------------------------------------------------------------------
/RainGenerator.xcodeproj/project.xcworkspace/contents.xcworkspacedata:
--------------------------------------------------------------------------------
1 | <?xml version="1.0" encoding="UTF-8"?>
2 | <Workspace
3 |    version = "1.0">
4 |    <FileRef
5 |       location = "self:">
6 |    </FileRef>
7 | </Workspace>
8 | 


--------------------------------------------------------------------------------
/RainGenerator/Assets.xcassets/AccentColor.colorset/Contents.json:
--------------------------------------------------------------------------------
 1 | {
 2 |   "colors" : [
 3 |     {
 4 |       "idiom" : "universal"
 5 |     }
 6 |   ],
 7 |   "info" : {
 8 |     "author" : "xcode",
 9 |     "version" : 1
10 |   }
11 | }
12 | 


--------------------------------------------------------------------------------
/RainGenerator/Assets.xcassets/AppIcon.appiconset/Contents.json:
--------------------------------------------------------------------------------
 1 | {
 2 |   "images" : [
 3 |     {
 4 |       "idiom" : "mac",
 5 |       "scale" : "1x",
 6 |       "size" : "16x16"
 7 |     },
 8 |     {
 9 |       "idiom" : "mac",
10 |       "scale" : "2x",
11 |       "size" : "16x16"
12 |     },
13 |     {
14 |       "idiom" : "mac",
15 |       "scale" : "1x",
16 |       "size" : "32x32"
17 |     },
18 |     {
19 |       "idiom" : "mac",
20 |       "scale" : "2x",
21 |       "size" : "32x32"
22 |     },
23 |     {
24 |       "idiom" : "mac",
25 |       "scale" : "1x",
26 |       "size" : "128x128"
27 |     },
28 |     {
29 |       "idiom" : "mac",
30 |       "scale" : "2x",
31 |       "size" : "128x128"
32 |     },
33 |     {
34 |       "idiom" : "mac",
35 |       "scale" : "1x",
36 |       "size" : "256x256"
37 |     },
38 |     {
39 |       "idiom" : "mac",
40 |       "scale" : "2x",
41 |       "size" : "256x256"
42 |     },
43 |     {
44 |       "idiom" : "mac",
45 |       "scale" : "1x",
46 |       "size" : "512x512"
47 |     },
48 |     {
49 |       "idiom" : "mac",
50 |       "scale" : "2x",
51 |       "size" : "512x512"
52 |     }
53 |   ],
54 |   "info" : {
55 |     "author" : "xcode",
56 |     "version" : 1
57 |   }
58 | }
59 | 


--------------------------------------------------------------------------------
/RainGenerator/Assets.xcassets/Contents.json:
--------------------------------------------------------------------------------
1 | {
2 |   "info" : {
3 |     "author" : "xcode",
4 |     "version" : 1
5 |   }
6 | }
7 | 


--------------------------------------------------------------------------------
/RainGenerator/AudioEngine.swift:
--------------------------------------------------------------------------------
  1 | import AVFoundation
  2 | import Foundation
  3 | import Synchronization
  4 | 
  5 | @MainActor
  6 | @Observable
  7 | class AudioEngine {
  8 |     struct Raindrop: Equatable {
  9 |         fileprivate var currentSample: Int = 0
 10 |         var sampleRate: Float = 44100
 11 |         var tInit: Float = 0.001
 12 |         var deltaT1: Float = 0.0075
 13 |         var deltaT2: Float = 0.015
 14 |         var deltaT3: Float = 0.030
 15 |         var a1: Float = 0.4
 16 |         var a2: Float = 0.7
 17 |         var frequency: Float = 400.0
 18 |         
 19 |         var time: Float {
 20 |             Float(currentSample) / sampleRate
 21 |         }
 22 |         
 23 |         mutating func generateSample() -> Float {
 24 |             let time = self.time
 25 |             currentSample += 1
 26 |             if time < tInit {
 27 |                 return 0.0
 28 |             } else if time < deltaT1 {
 29 |                 let t = .pi * (time - tInit) / (deltaT1 - tInit) - 0.5 * .pi
 30 |                 return a1 * cos(t)
 31 |             } else if time < deltaT2 {
 32 |                 return 0.0
 33 |             } else if time < deltaT3 {
 34 |                 let bubbleTime = time - deltaT2
 35 |                 let decay = exp(-6 * bubbleTime / (deltaT3 - deltaT2))
 36 |                 let expand = exp(0.5 * bubbleTime / (deltaT3 - deltaT2))
 37 |                 return decay * a2 * sin(2.0 * .pi * frequency * bubbleTime * expand)
 38 |             } else if time < deltaT3 + tInit {
 39 |                 return 0.0
 40 |             }
 41 |             return 0.0
 42 |         }
 43 |     }
 44 |     
 45 |     struct Parameters: Equatable {
 46 |         var raindrop = Raindrop()
 47 |         
 48 |         var volume: Float = 0.5
 49 |         var dropsPerMinute: Float = 300
 50 |         var dropRandomness: Float = 1.0
 51 |         var frequencyRandomness: Float = 0.75
 52 |         var pinkNoise: Float = 0.025
 53 |         var brownNoise: Float = 0.05
 54 |         var whiteNoise: Float = 0.0
 55 |         
 56 |         func createNewRaindrop(fixedValue: Bool) -> Raindrop {
 57 |             var newDrop = raindrop
 58 |             
 59 |             // Amplitude parameters
 60 |             newDrop.a1 = Float.randomnessAroundMidpoint(randomness: fixedValue ? 0 : dropRandomness, midpoint: newDrop.a1)
 61 |             newDrop.a2 = Float.randomnessAroundMidpoint(randomness: fixedValue ? 0 : dropRandomness, midpoint: newDrop.a2)
 62 |             
 63 |             // Timing parameters
 64 |             newDrop.deltaT1 = newDrop.tInit + Float.randomnessAroundMidpoint(randomness: fixedValue ? 0 : dropRandomness, midpoint: newDrop.deltaT1)
 65 |             newDrop.deltaT2 = newDrop.deltaT1 + Float.randomnessAroundMidpoint(randomness: fixedValue ? 0 : dropRandomness, midpoint: newDrop.deltaT2)
 66 |             newDrop.deltaT3 = newDrop.deltaT2 + Float.randomnessAroundMidpoint(randomness: fixedValue ? 0 : dropRandomness, midpoint: newDrop.deltaT3)
 67 |             
 68 |             // Sound parameters
 69 |             newDrop.frequency = Float.randomnessAroundMidpoint(randomness: fixedValue ? 0 : dropRandomness, midpoint: newDrop.frequency)
 70 |             
 71 |             return newDrop
 72 |         }
 73 |     }
 74 |     
 75 |     struct GeneratorState {
 76 |         var currentTime: Float = 0.0
 77 |         var raindrops: [Raindrop] = []
 78 |         var nextDropTime: Float = 0
 79 |         var pinkNoiseState: [Float] = Array(repeating: 0.0, count: 7)
 80 |         var brownNoiseState: Float = 0.0
 81 |         var parameters = Parameters()
 82 |         
 83 |         mutating func generatePinkNoise() -> Float {
 84 |             let white = Float.random(in: -1.0...1.0)
 85 |             pinkNoiseState[0] = 0.99886 * pinkNoiseState[0] + white * 0.0555179
 86 |             pinkNoiseState[1] = 0.99332 * pinkNoiseState[1] + white * 0.0750759
 87 |             pinkNoiseState[2] = 0.96900 * pinkNoiseState[2] + white * 0.1538520
 88 |             pinkNoiseState[3] = 0.86650 * pinkNoiseState[3] + white * 0.3104856
 89 |             pinkNoiseState[4] = 0.55000 * pinkNoiseState[4] + white * 0.5329522
 90 |             pinkNoiseState[5] = -0.7616 * pinkNoiseState[5] - white * 0.0168980
 91 |             let pink = pinkNoiseState[0] + pinkNoiseState[1] + pinkNoiseState[2] + pinkNoiseState[3] + pinkNoiseState[4] + pinkNoiseState[5] + pinkNoiseState[6] + white * 0.5362
 92 |             pinkNoiseState[6] = white * 0.115926
 93 |             return pink
 94 |         }
 95 |         
 96 |         func generateWhiteNoise() -> Float {
 97 |             return Float.random(in: -1.0...1.0)
 98 |         }
 99 |         
100 |         mutating func generateBrownNoise() -> Float {
101 |             let white = Float.random(in: -1.0...1.0)
102 |             brownNoiseState = (brownNoiseState + white).clamped(to: -1.0...1.0)
103 |             return brownNoiseState
104 |         }
105 |     }
106 |     
107 |     private var engine: AVAudioEngine
108 |     private var mainMixer: AVAudioMixerNode
109 |     private var player: AVAudioSourceNode?
110 |     
111 |     var parameters = Parameters() {
112 |         didSet {
113 |             generatorState.withLock { state in
114 |                 state.parameters = parameters
115 |             }
116 |         }
117 |     }
118 |     
119 |     private let generatorState = Mutex(GeneratorState())
120 |     
121 |     private(set) var isRunning: Bool = false
122 |     
123 |     init() {
124 |         let engine = AVAudioEngine()
125 |         self.engine = engine
126 |         mainMixer = engine.mainMixerNode
127 |         let outputFormat = engine.outputNode.outputFormat(forBus: 0)
128 |         let playerFormat = AVAudioFormat(standardFormatWithSampleRate: outputFormat.sampleRate, channels: 1)!
129 |         parameters.raindrop.sampleRate = Float(playerFormat.sampleRate)
130 |         
131 |         let player = AVAudioSourceNode { @Sendable [weak self] _, _, frameCount, audioBufferList in
132 |             guard let self = self else { return noErr }
133 |             return self.generateAudio(audioBufferList: audioBufferList, frameCount: frameCount)
134 |         }
135 |         self.player = player
136 |         
137 |         engine.attach(player)
138 |         engine.connect(player, to: mainMixer, format: playerFormat)
139 |         engine.connect(mainMixer, to: engine.outputNode, format: playerFormat)
140 |         mainMixer.outputVolume = 1.0
141 |     }
142 |     
143 |     func raindropSampleCount() -> Int {
144 |         let newDrop = parameters.createNewRaindrop(fixedValue: true)
145 |         return Int((newDrop.deltaT3 + newDrop.tInit) * newDrop.sampleRate)
146 |     }
147 |     
148 |     func generateWaveform(samples: Int) -> [Float] {
149 |         var waveform: [Float] = []
150 |         var raindrop = parameters.createNewRaindrop(fixedValue: true)
151 |         
152 |         for _ in 0..<samples {
153 |             let sample = raindrop.generateSample()
154 |             waveform.append(sample)
155 |         }
156 |         return waveform
157 |     }
158 |     
159 |     private nonisolated func generateAudio(
160 |         audioBufferList: UnsafeMutablePointer<AudioBufferList>,
161 |         frameCount: AVAudioFrameCount
162 |     ) -> OSStatus {
163 |         let ablPointer = UnsafeMutableAudioBufferListPointer(audioBufferList)
164 |         let frameLength = Int(frameCount)
165 |         
166 |         var generatorState = self.generatorState.withLock { state in
167 |             state
168 |         }
169 |         let parameters = generatorState.parameters
170 |         
171 |         let dropInterval = 60.0 / parameters.dropsPerMinute
172 |         for frame in 0..<frameLength {
173 |             // Check if it's time to add a new raindrop
174 |             if generatorState.currentTime >= generatorState.nextDropTime {
175 |                 generatorState.raindrops.append(parameters.createNewRaindrop(fixedValue: false))
176 |                 generatorState.nextDropTime = generatorState.currentTime + Float.randomnessAroundMidpoint(randomness: 0.95 * parameters.frequencyRandomness, midpoint: dropInterval)
177 |             }
178 |             
179 |             // Sum the samples from all active raindrops
180 |             var sample: Float = 0.0
181 |             generatorState.raindrops = generatorState.raindrops.filter { drop in
182 |                 return drop.time < (drop.deltaT3 + drop.tInit)  // Keep drop if it hasn't finished playing
183 |             }
184 |             
185 |             for i in 0..<generatorState.raindrops.count {
186 |                 sample += generatorState.raindrops[i].generateSample()
187 |                 generatorState.raindrops[i].currentSample += 1
188 |             }
189 |             
190 |             // Add pink noise to the sample
191 |             sample += generatorState.generateWhiteNoise() * parameters.whiteNoise + parameters.brownNoise * generatorState.generateBrownNoise() + generatorState.generatePinkNoise() * parameters.pinkNoise
192 |             
193 |             // Write the sample to all channels
194 |             for buffer in ablPointer {
195 |                 let buf: UnsafeMutableBufferPointer<Float> = UnsafeMutableBufferPointer(buffer)
196 |                 buf[frame] = sample * parameters.volume
197 |             }
198 |             
199 |             generatorState.currentTime += 1.0 / parameters.raindrop.sampleRate
200 |         }
201 |         
202 |         self.generatorState.withLock { state in
203 |             state = generatorState
204 |         }
205 |         
206 |         return noErr
207 |     }
208 |     
209 |     func start() throws {
210 |         try engine.start()
211 |         isRunning = true
212 |     }
213 |     
214 |     func stop() {
215 |         engine.pause()
216 |         isRunning = false
217 |     }
218 | }
219 | 
220 | extension Float {
221 |     func clamped(to: ClosedRange<Float>) -> Float {
222 |         if self < to.lowerBound {
223 |             return to.lowerBound
224 |         } else if self > to.upperBound {
225 |             return to.upperBound
226 |         } else {
227 |             return self
228 |         }
229 |     }
230 |     
231 |     static func randomnessAroundMidpoint(randomness: Float, midpoint: Float) -> Float {
232 |         if randomness != 0 {
233 |             let scale = randomness > 1 ? randomness : 1
234 |             let scaledRandomness = randomness > 1 ? 1 : randomness
235 |             return Float.random(in: (scale * midpoint * (1 - scaledRandomness))...(scale * midpoint * (1 + scaledRandomness)))
236 |         } else {
237 |             return midpoint
238 |         }
239 |     }
240 | }
241 | 


--------------------------------------------------------------------------------
/RainGenerator/ContentView.swift:
--------------------------------------------------------------------------------
  1 | //
  2 | //  ContentView.swift
  3 | //  RainGenerator
  4 | //
  5 | //  Created by Matthew Gallagher on 1/12/2024.
  6 | //
  7 | 
  8 | import SwiftUI
  9 | import Charts
 10 | 
 11 | struct ContentView: View {
 12 |     @State private var audioEngine = AudioEngine()
 13 |     @State private var waveform: [Float] = []
 14 | 
 15 |     var body: some View {
 16 |         VStack(spacing: 20) {
 17 |             HStack(alignment: .top, spacing: 20) {
 18 |                 VStack(alignment: .leading) {
 19 |                     Text("Impact duration: \(audioEngine.parameters.raindrop.deltaT1 * 1000) milliseconds")
 20 |                     Slider(value: $audioEngine.parameters.raindrop.deltaT1, in: 0.0002...0.1)
 21 |                     
 22 |                     Text("Impact amplitude: \(audioEngine.parameters.raindrop.a1) amplitude")
 23 |                     Slider(value: $audioEngine.parameters.raindrop.a1, in: 0...1.5)
 24 |                     
 25 |                     Text("Pause duration: \(audioEngine.parameters.raindrop.deltaT2 * 1000) milliseconds")
 26 |                     Slider(value: $audioEngine.parameters.raindrop.deltaT2, in: 0.0002...0.08)
 27 |                     
 28 |                     Text("Bubble duration: \(audioEngine.parameters.raindrop.deltaT3 * 1000) milliseconds")
 29 |                     Slider(value: $audioEngine.parameters.raindrop.deltaT3, in: 0.001...0.4)
 30 |                     
 31 |                     Text("Bubble amplitude: \(audioEngine.parameters.raindrop.a2) amplitude")
 32 |                     Slider(value: $audioEngine.parameters.raindrop.a2, in: 0...1.5)
 33 | 
 34 |                     Text("Bubble frequency: \(audioEngine.parameters.raindrop.frequency) Hz")
 35 |                     Slider(value: $audioEngine.parameters.raindrop.frequency, in: 2...2000)
 36 |                 }
 37 |                 VStack(alignment: .leading) {
 38 |                     Text("Drop randomness: \(Int(audioEngine.parameters.dropRandomness * 100))%")
 39 |                     Slider(value: $audioEngine.parameters.dropRandomness, in: 0...2)
 40 |                     
 41 |                     Text("Drop rate: \(Int(audioEngine.parameters.dropsPerMinute)) per minute")
 42 |                     Slider(value: $audioEngine.parameters.dropsPerMinute, in: 20...4000)
 43 |                     
 44 |                     Text("Rate randomness: \(Int(audioEngine.parameters.frequencyRandomness * 100))%")
 45 |                     Slider(value: $audioEngine.parameters.frequencyRandomness, in: 0...1)
 46 |                     
 47 |                     Text("White noise: \(audioEngine.parameters.whiteNoise * 200)%")
 48 |                     Slider(value: $audioEngine.parameters.whiteNoise, in: 0...0.5)
 49 |                     
 50 |                     Text("Brown noise: \(audioEngine.parameters.brownNoise * 200)%")
 51 |                     Slider(value: $audioEngine.parameters.brownNoise, in: 0...0.5)
 52 |                     
 53 |                     Text("Pink noise: \(audioEngine.parameters.pinkNoise * 200)%")
 54 |                     Slider(value: $audioEngine.parameters.pinkNoise, in: 0...0.5)
 55 |                 }
 56 |             }
 57 |             .padding(.horizontal)
 58 |             
 59 |             Chart {
 60 |                 ForEach(Array(waveform.enumerated()), id: \.offset) { index, value in
 61 |                     LineMark(
 62 |                         x: .value("Time", Float(index) / audioEngine.parameters.raindrop.sampleRate),
 63 |                         y: .value("Amplitude", value)
 64 |                     )
 65 |                     .foregroundStyle(by: .value("Segment", color(index: index)))
 66 |                 }
 67 |             }
 68 |             .chartXAxisLabel("Seconds", position: .bottomLeading)
 69 |             .chartYScale(domain: -1.0...1.0)
 70 |             .chartLegend(position: .overlay)
 71 |             
 72 |             Text("Volume: \(Int(audioEngine.parameters.volume * 100))%")
 73 |             Slider(value: $audioEngine.parameters.volume, in: 0...1)
 74 |             
 75 |             Button {
 76 |                 if audioEngine.isRunning {
 77 |                     audioEngine.stop()
 78 |                 } else {
 79 |                     try? audioEngine.start()
 80 |                 }
 81 |             } label: {
 82 |                 Text(audioEngine.isRunning ? "Stop" : "Start").frame(maxWidth: .infinity)
 83 |             }
 84 |         }
 85 |         .padding()
 86 |         .onChange(of: audioEngine.parameters, initial: true) { _, _ in
 87 |             updateWaveform()
 88 |         }
 89 |     }
 90 |     
 91 |     private func color(index: Int) -> String {
 92 |         audioEngine.parameters.raindrop.color(index: index)
 93 |     }
 94 |     
 95 |     private func updateWaveform() {
 96 |         waveform = audioEngine.generateWaveform(samples: audioEngine.raindropSampleCount())
 97 |     }
 98 | }
 99 | 
100 | private extension AudioEngine.Raindrop {
101 |     func color(index: Int) -> String {
102 |         switch Float(index) / sampleRate {
103 |         case 0..<tInit: return "Padding (Initial)"
104 |         case (tInit)..<(tInit + deltaT1): return "Impact"
105 |         case (tInit + deltaT1)..<(tInit + deltaT1 + deltaT2): return "Pause"
106 |         case (tInit + deltaT1 + deltaT2)..<(tInit + deltaT1 + deltaT2 + deltaT3): return "Bubble"
107 |         default: return "Padding (Trailing)"
108 |         }
109 |     }
110 | }
111 | 
112 | #Preview(
113 |     "Content",
114 |     traits: .fixedLayout(width: 700, height: 800)
115 | ) {
116 |     ContentView()
117 | }
118 | 


--------------------------------------------------------------------------------
/RainGenerator/Preview Content/Preview Assets.xcassets/Contents.json:
--------------------------------------------------------------------------------
1 | {
2 |   "info" : {
3 |     "author" : "xcode",
4 |     "version" : 1
5 |   }
6 | }
7 | 


--------------------------------------------------------------------------------
/RainGenerator/RainGenerator.entitlements:
--------------------------------------------------------------------------------
 1 | <?xml version="1.0" encoding="UTF-8"?>
 2 | <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
 3 | <plist version="1.0">
 4 | <dict>
 5 | 	<key>com.apple.security.app-sandbox</key>
 6 | 	<true/>
 7 | 	<key>com.apple.security.files.user-selected.read-only</key>
 8 | 	<true/>
 9 | </dict>
10 | </plist>
11 | 


--------------------------------------------------------------------------------
/RainGenerator/RainGeneratorApp.swift:
--------------------------------------------------------------------------------
 1 | //
 2 | //  RainGeneratorApp.swift
 3 | //  RainGenerator
 4 | //
 5 | //  Created by Matthew Gallagher on 1/12/2024.
 6 | //
 7 | 
 8 | import SwiftUI
 9 | 
10 | @main
11 | struct RainGeneratorApp: App {
12 |     var body: some Scene {
13 |         WindowGroup {
14 |             ContentView()
15 |         }
16 |         .defaultSize(width: 800, height: 800)
17 |     }
18 | }
19 | 


--------------------------------------------------------------------------------