/
ChromaKeyMaterial.swift
93 lines (68 loc) · 2.75 KB
/
ChromaKeyMaterial.swift
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
//
// ChromaKeyMaterial.swift
// SceneKitTransparentVideo
//
// Created by Turkowski on 21/09/2017.
// Copyright © 2017 Turkowski. All rights reserved.
//
import SceneKit
public class ChromaKeyMaterial: SCNMaterial {
// MARK: - Public properties
public var backgroundColor: UIColor {
didSet { didSetBackgroundColor() }
}
public var thresholdSensitivity: Float {
didSet { didSetThresholdSensitivity() }
}
public var smoothing: Float {
didSet { didSetSmoothing() }
}
// MARK: - Initialization
public init(backgroundColor: UIColor = .green, thresholdSensitivity: Float = 0.05, smoothing: Float = 0.0) {
self.backgroundColor = backgroundColor
self.thresholdSensitivity = thresholdSensitivity
self.smoothing = smoothing
super.init()
didSetBackgroundColor()
didSetThresholdSensitivity()
didSetSmoothing()
// chroma key shader is based on GPUImage
// https://github.com/BradLarson/GPUImage/blob/master/framework/Source/GPUImageChromaKeyFilter.m
let surfaceShader =
"""
uniform vec3 c_colorToReplace;
uniform float c_thresholdSensitivity;
uniform float c_smoothing;
#pragma transparent
#pragma body
vec3 textureColor = _surface.diffuse.rgb;
float maskY = 0.2989 * c_colorToReplace.r + 0.5866 * c_colorToReplace.g + 0.1145 * c_colorToReplace.b;
float maskCr = 0.7132 * (c_colorToReplace.r - maskY);
float maskCb = 0.5647 * (c_colorToReplace.b - maskY);
float Y = 0.2989 * textureColor.r + 0.5866 * textureColor.g + 0.1145 * textureColor.b;
float Cr = 0.7132 * (textureColor.r - Y);
float Cb = 0.5647 * (textureColor.b - Y);
float blendValue = smoothstep(c_thresholdSensitivity, c_thresholdSensitivity + c_smoothing, distance(vec2(Cr, Cb), vec2(maskCr, maskCb)));
float a = blendValue;
_surface.transparent.a = a;
"""
shaderModifiers = [
.surface: surfaceShader,
]
}
required public init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
// MARK: - Private methods
private func didSetBackgroundColor() {
let rgb = backgroundColor.cgColor.components!.map{Float($0)}
let vector = SCNVector3(x: rgb[0], y: rgb[1], z: rgb[2])
setValue(vector, forKey: "c_colorToReplace")
}
private func didSetSmoothing() {
setValue(smoothing, forKey: "c_smoothing")
}
private func didSetThresholdSensitivity() {
setValue(thresholdSensitivity, forKey: "c_thresholdSensitivity")
}
}