C++之openFrameworks框架介绍

ofBackground(0); // 用黑色清空屏幕，0 表示完全白色的灰度颜色。
ofSetColor(255); // 将绘制颜色设置为白色。
 
// 在下面绘制一些图形。
ofDrawRectangle(50, 50, 100, 100); // 左上角坐标为 (50, 50)，宽度为 100，高度为 100。
ofDrawCircle(250, 100, 50); // 中心坐标为 (250, 100)，半径为 50。
ofDrawEllipse(400, 100, 80, 100); // 中心坐标为 (400, 100)，宽度为 80，高度为 100。
ofDrawTriangle(500, 150, 550, 50, 600, 150); // 三个顶点坐标分别为 (500, 150), (550, 50), (600, 150)。
ofDrawLine(700, 50, 700, 150); // 从 (700, 50) 到 (700, 150) 的直线。

ofBackground(0);
ofSetColor(255);
ofFill();
ofDrawRectangle(50, 50, 100, 100);
ofDrawCircle(250, 100, 50);
ofDrawEllipse(400, 100, 80, 100);
ofDrawTriangle(500, 150, 550, 50, 600, 150);
ofDrawLine(700, 50, 700, 150);
ofNoFill();
ofDrawRectangle(50, 200, 100, 100);
ofDrawCircle(250, 250, 50);
ofDrawEllipse(400, 250, 80, 100);
ofDrawTriangle(500, 300, 550, 200, 600, 300);
ofDrawLine(700, 200, 700, 300);

// 如果左鼠标按钮被按下...
if (ofGetMousePressed(OF_MOUSE_BUTTON_LEFT)) {  
    ofSetColor(255);
    ofSetRectMode(OF_RECTMODE_CENTER);
    ofDrawRectangle(
        ofGetMouseX(), 
        ofGetMouseY(), 
        50, 
        50
    );  
    // 在鼠标位置绘制一个宽高为50的矩形，居中对齐
}

// 我们仍然希望在黑色背景上进行绘制，因此在进行画刷操作之前需要先绘制背景
ofSetBackgroundAuto(false); 
ofBackground(0); // 设置背景颜色为黑色

if (ofGetMousePressed(OF_MOUSE_BUTTON_LEFT)) { // 如果左鼠标按钮被按下...
  float randomColor = ofRandom(50, 255); // 随机生成颜色值，范围从50到255
  ofSetColor(randomColor); // 设置矩形的颜色为随机生成的颜色值，排除黑色背景上不可见的灰度值（0 - 50）
  ofSetRectMode(OF_RECTMODE_CENTER); 
  ofDrawRectangle(ofGetMouseX(), ofGetMouseY(), 50, 50); // 在鼠标位置绘制一个宽高为50的矩形，居中对齐
}

if (ofGetMousePressed(OF_MOUSE_BUTTON_LEFT)) { // If the left mouse button is pressed...
ofSetRectMode(OF_RECTMODE_CENTER);
int numRects = 10;
for (int r=0; r<numRects; r++) {
ofSetColor(ofRandom(50, 255));
float width = ofRandom(5, 20);
float height = ofRandom(5, 20);
float xOffset = ofRandom(-40, 40);
float yOffset = ofRandom(-40, 40);
ofDrawRectangle(ofGetMouseX()+xOffset, ofGetMouseY()+yOffset, width, height);
}
}

ofColor myOrange(255, 132, 0); // Defining an opaque orange color - specified using RGB
ofColor myBlue(0, 0, 255, 50); // Defining a transparent blue color - specified using RGBA
// We can access the red, green, blue and alpha channels like this:
ofColor myGreen(0, 0, 255, 255);
cout << "Red channel:" << myGreen.r << endl;
cout << "Green channel:" << myGreen.g << endl;
cout << "Blue channel:" << myGreen.b << endl;
cout << "Alpha channel:" << myGreen.a << endl;
// We can also set the red, green, blue and alpha channels like this:
ofColor myYellow;
myYellow.r = 255; myYellow.b = 0; myYellow.g = 255; myYellow.a = 255;
// We can also make use of some predefined colors provided by openFrameworks:
ofColor myAqua = ofColor::aqua;
ofColor myPurple = ofColor::plum;

ofVec2f mousePos(ofGetMouseX(), ofGetMouseY());
// Define a triangle at the origin (0,0) that points to the right
ofVec2f p1(0, 25.0);
ofVec2f p2(100, 0);
ofVec2f p3(0, -25.0);
// Shift the triangle to the mouse position
p1 += mousePos;
p2 += mousePos;
p3 += mousePos;