java - 用按钮控制透明度

Question

我正在尝试创建一个显示原色的草图，然后您可以使用按钮或 slider 控制其透明度。我正在使用 CnttrolP5 库。问题是，每当我将透明度变量放入 color() 时，一切都会变得困惑，甚至颜色都不会出现。

查看代码:

 import controlP5.*;

ControlP5 cp5;

int transparency;
color c = color(0, 160, 25);
color red;
color green;
color blue;


void setup() {
    size(400, 600);
    gui();

    red = color(255, 0, 0, transparency); // WHWENEVER I PUT TRASNPARENCY VALUE DOES NOT WORK
    green = color(0, 255, 0, transparency);
    blue = color(0, 0, 255, transparency);
    noStroke();
    smooth();

  }
  // create gui
void gui() {

  cp5 = new ControlP5(this);

  // create radio button


  cp5.addRadioButton("radio")
    .setPosition(40, 200)
    .setItemWidth(20)
    .setItemHeight(20)
    .addItem("red", 0)
    .addItem("green", 1)
    .addItem("blue", 2)
    .setColorLabel(color(255))
    .activate(2)

  ;

  cp5.addRadioButton("level")
    .setPosition(100, 200)
    .setItemWidth(20)
    .setItemHeight(20)
    .addItem("ONE", 0)
    .addItem("TWO", 1)
    .addItem("THREE", 2)
    .addItem("FOUR", 3)
    .addItem("FIVE", 4)
    .addItem("SIX", 5)
    .addItem("SEVEN", 6)
    .addItem("EIGHT", 7)
    .addItem("NINE", 8)
    .addItem("TEN", 9)
    .setColorLabel(color(255))
    .activate(2)

  ;

  //add slider bar


  /* cp5.addSlider("level")
    .setPosition(60,20)
    .setSize(100,20)
    .setRange(0,10)
    .setValue(5)
    .setNumberOfTickMarks(11)
    .setSliderMode(Slider.FLEXIBLE)
    ;*/

}


void radio(int theC) {
  switch (theC) {
    case (0):
      c = red;
      break;
    case (1):
      c = green;
      break;
    case (2):
      c = blue;
      break;

  }
}

void level(int theC) {
  switch (theC) {
    case (0):
      transparency = 15;
      break;
    case (1):
      transparency = 13;
      break;
    case (2):
      transparency = 11;
      break;
    case (3):
      transparency = 9;
      break;
    case (4):
      transparency = 7;
      break;
    case (5):
      transparency = 6;
      break;
    case (6):
      transparency = 5;
      break;
    case (7):
      transparency = 4;
      break;
    case (8):
      transparency = 2;
      break;
    case (9):
      transparency = 1;
      break;

  }
}

void draw() {
  background(220);

  fill(c); //fill with color

  ellipse(200, 400, 100, 100);

}

Answer 1

您在setup()中初始化了颜色(红、绿、蓝)变量，并且从未更改它们。如果你想改变透明度，你需要进入draw()，并且变量transparency需要初始化为某个值。

此外，仅当用户单击“单选”按钮时才更改颜色，以改进这一点，您需要从“radio()”抽象颜色逻辑

void radio(int theC) {
  mode = theC;
}

其中mode是存储颜色模式的整数变量。并更新了 draw() 函数:

void draw() {
  background(220);

  switch (mode) {
    case (0):
      c = color(255, 0, 0, transparency);
      break;
    case (1):
      c = color(0, 255, 0, transparency);
      break;
    case (2):
      c = color(0, 0, 255, transparency);
      break;    
  }

  fill(c); //fill with color
  ellipse(200, 400, 100, 100);
}

正如 @rlinden 正确提到的，您还应该将 alpha 值更新为 0-255。