{%hackmd BJrTq20hE %}
# 開發紀錄 Week3
## UI Screenshot

## UI details

### Combobox
- 藉由Combobox來選擇欲呈現的波型
- 將各種波型加入ComboBox中

    synthChoose.addItem("Sine",1);
    synthChoose.addItem("Square", 2);
    synthChoose.addItem("Sawtooth", 3);
    synthChoose.addItem("Triangle", 4);

- 利用```addAndMakeVisible(synthChoose);``` 將按鈕加入UI
- 最後記得resize combobox的位置
- ``` synthChoose.setBounds(x, y + 50, sliderWidth, sliderHeight);```

### AudioProcessorValueTreeState
- 將Combobox接收到的數值，送至這個Tree中儲存

waveComboBoxAttachment.reset(new juce::AudioProcessorValueTreeState
::ComboBoxAttachment(audioProcessor.tree, "wave", synthChoose));

- 之後在Processer端利用getRawParameterValue()做接收

 myVoice->setChannel(tree.getRawParameterValue("wave")->load());

## Generate Wave Value

### Square wave
- 藉由sin(currentAngle)判斷當前象限，若為一二象限為+1，否則為-1

value = ((std::sin(currentAngle) > 0) ? 1 : -1) ;

### Sawtooth wave
- 想法是先算出currentAngle在twoPi中的比例(藉由將currentAngle+Pi調整起始位置)

proportion = fmod(currentAngle + juce::MathConstants<float>::pi, 
juce::MathConstants<float>::twoPi) / juce::MathConstants<float>::twoPi;

- 將斜率代入後再將value調整至1~-1之間即可

value = (proportion * 2 - 1);

### Triangle wave
- 和鋸齒波想法相似，一樣是先將比例算出(藉由將currentAngle+halfPi調整起始位置)

 proportion = fmod(currentAngle + juce::MathConstants<float>::halfPi,
 juce::MathConstants<float>::twoPi) / juce::MathConstants<float>::twoPi;

- 但三角波有兩條不一樣的線，所以分別在 0~0.5 用一斜率 0.5~1 用另一斜率，再將value調整至1~-1

if (proportion < 0.5)
    value = ((proportion * 2) * 2 - 1);
else
    value = 2 - ((proportion - 0.5) * 2) * 2 - 1;