模拟方案1:
void setup() { size(500, 500); smooth(); } float yPos=25; float g=.15; float acceleration=0; void draw() { background(0); makeball(); yPos += acceleration; //ball drop or bounce back acceleration += g; //accelerate speed add g //when bounce back, -acceleration+g = slower speed if (yPos>height-25) { acceleration=-acceleration/1.15; //when hit bottom, bounce back, but drop down at lower height //Thanks to Mauricio } } void makeball() { ellipse(width/2, yPos, 50, 50); fill(255); }
方案2:
// Learning Processing // Daniel Shiffman // http://www.learningprocessing.com // Example 5-9: Simple Gravity float x = 100; // x location of square float y = 0; // y location of square float speed = 0; // speed of square // A new variable, for gravity (i.e. acceleration). // We use a relatively small number (0.1) because this accelerations accumulates over time, increasing the speed. // Try changing this number to 2.0 and see what happens. float gravity = 0.1; void setup() { size(200,200); } void draw() { background(255); // Display the square fill(175); stroke(0); rectMode(CENTER); rect(x,y,10,10); // Add speed to location. y = y + speed; // Add gravity to speed. speed = speed + gravity; // If square reaches the bottom // Reverse speed if (y > height) { // Multiplying by -0.95 instead of -1 slows the square down each time it bounces (by decreasing speed). 让speed乘以-0.95《1,使高度小于最开始的高度。 // This is known as a "dampening" effect and is a more realistic simulation of the real world (without it, a ball would bounce forever). speed = speed * -0.95; } }
2种方法都差不多,只不过参数不同而已。