用p5.js实现一个小动画——故宫橘猫赏秋图

互动媒体第二次作业要求我们手绘一幅动画，再用代码实现出动画。由于时间原因，手绘并没有画动画，而是以插画的形式画了一张，然后p5实现了动画。
这里先放效果图：

板绘插图

码绘效果图

这里强烈建议直接运行代码！！！gif丢帧！！！可怜我的渐变啊啊啊啊！！！
下面附上完整代码：

var Width=600;
var Height=700;
var pixel=1;var Y_AXIS = 1;
var X_AXIS = 2;var skyHeight=190;
var wall_Width=600;
var wall_Height=300;
var wuyan_width=120;
var wuyan_height=20;
var quad_width=70;
var quad_height=30;
var center_x=500;
var center_y=115;
var cat_scale=111;var easing=1; var Time;//face_color=color(180,180,150,0.5*255);
function setup() {createCanvas(Width,Height); }function draw() { frameRate(5);drawwall();  drawsky();push();translate(10,-5);YinxingTree();pop();draw_wallshadow();if(center_x<-10)center_x=650;center_x-=15*easing;drawcat(cat_scale,center_x,center_y);translate(10,-25);noStroke();fill(30);rect(Width-10,0,200,Height);push();YinxingTree();pop();}function drawcat(cat_scale,center_x,center_y){stroke(200,200,240);noStroke();//肚子pos1_x=center_x-(cat_scale)/3;pos1_y=center_y+(cat_scale)*2/5-5;pos2_x=center_x+(cat_scale*1/3);pos2_y=center_y+(cat_scale)*2/5;//前体pos3_x=pos1_x-(cat_scale/5);pos3_y=center_y+(cat_scale)*2/5;pos4_x=pos1_x-(cat_scale/8);pos4_y=center_y+(cat_scale)/15;pos5_x=pos4_x-(cat_scale/8);pos5_y=pos4_y-(cat_scale)/20;//头pos6_x=pos5_x-(cat_scale/4);pos6_y=pos5_y-(cat_scale)/6;pos7_x=pos5_x-(cat_scale/6);pos7_y=pos5_y-(cat_scale)/30;pos8_x=pos5_x-(cat_scale)*3/8;pos8_y=pos5_y+(cat_scale)/8;pos9_x=pos8_x+(cat_scale)/5;pos9_y=pos8_y+(cat_scale)/5;//屁股pos10_x=pos2_x-(cat_scale/4)*0;pos10_y=pos2_y-(cat_scale)*1/3;pos11_x=pos10_x+(cat_scale*1/8);pos11_y=pos10_y+(cat_scale)/10;fill(220,200,180);triangle(center_x,center_y,pos1_x,pos1_y,pos2_x,pos2_y);triangle(center_x,center_y,pos1_x,pos1_y,pos3_x,pos3_y);fill(150,70,10);triangle(center_x,center_y,pos3_x,pos3_y,pos4_x,pos4_y);triangle(pos3_x,pos3_y,pos4_x,pos4_y,pos5_x,pos5_y);triangle(pos3_x,pos3_y,pos5_x,pos5_y,pos6_x,pos6_y);fill(150,70,10);triangle(pos3_x,pos3_y,pos7_x,pos7_y,pos8_x,pos8_y);fill(180,100,10);triangle(pos8_x,pos8_y,pos9_x,pos9_y,pos5_x,pos5_y);fill(150,70,10);triangle(center_x,center_y,pos2_x,pos2_y,pos10_x,pos10_y);triangle(pos2_x,pos2_y,pos10_x,pos10_y,pos11_x,pos11_y);fill(180);feetControl(pos1_x-6,pos1_y);feetControl(pos2_x-4,pos2_y);noFill();weiba(pos11_x,pos11_y);}function weiba(x,y){push();strokeWeight(10);stroke(150,70,10);x1=x-20;y1=y;x2=x+20;y2=y-20;x3=x+25;y3=y+5;x4=x+55;y4=y-20;bezier(x1,y1,x2,y2,x3,y3,x4,y4);noStroke();pop();}function feetControl(x,y){if(x%2==0){rect(x-(cat_scale)/10,y-8,(cat_scale)/10,(cat_scale)*1/3+8);    }else{quad(x,y-10,x-(cat_scale)/10,y-10,x-(cat_scale)/10+(cat_scale/10),y+(cat_scale)*1/3,x+(cat_scale/10),y+(cat_scale)*1/3);quad(x,y-15,x-(cat_scale)/10,y-15,x-(cat_scale)/10-(cat_scale/5),y+(cat_scale)*1/3,x-(cat_scale/5),y+(cat_scale)*1/3);}}function segment(trans_x, trans_y, a,segLength) {push();translate(trans_x, trans_y);rotate(a);rect();pop();}function draw_wallshadow(){noStroke();var c1=color(160,10,0);var c2=color(80,10,80);setGradient(0,600,Width,150,c1,c2,1);noStroke();fill(160,10,0);for(var i=0;i<Width;i++){arc(i,600,50,15,PI,0);i=i+80;}}function drawwall(){noStroke();fill(100,10,0);rect(0, 0, Width, Height);fill(190,70,20);rect(0, Height-wall_Height, wall_Width, wall_Height);drawWuYan1();   drawWuYan2(); drawWuYan3();drawWuYan4();}function drawWuYan1(){stroke(20);fill(190,100,10);for(var i=0;i<Width;i++){rect(i-5,wall_Height+70,wuyan_width,wuyan_height);i=i+wuyan_width;} }function drawWuYan2(){var cwu2_1=color(50,120,30);var cwu2_2=color(60,10,0);for(var j=0;j<Width+80;j++){setGradient(j-65,wall_Height+35,wuyan_width,wuyan_height+10,cwu2_1,cwu2_2,1);stroke(180,130,20);rect(j-65,wall_Height+36,wuyan_width,wuyan_height+10);j=j+wuyan_width;} var cwu3_1=color(10,20,10);var cwu3_2=color(80,100,20);fill(50,120,30);setGradient(0,wall_Height-15,Width,50,cwu3_1,cwu3_2,1);}function drawWuYan3(){noStroke();fill(190,150,90);for(var k=0;k<Width;k++){rect(k,skyHeight,wuyan_width,10);k=k+wuyan_width;}fill(190,100,10);rect(0,skyHeight+15,Width,12);fill(190,110,30);rect(0,skyHeight+35,Width,35);}function drawPIdwon(x_trans){stroke(90,50,50);push();translate(x_trans, skyHeight+100);rotate(0.0);fill(140,100,50);arc(0, 0, quad_width, quad_width-15, 0, PI);pop();}function drawPIdwon_shadow(x_trans,shadow){noStroke();push();translate(x_trans, skyHeight+100);rotate(0.0);fill(10,20,10);arc(0, 0, quad_width+shadow, quad_width+shadow, 0, PI);pop();}function drawquad(i,j,x_trans){var c1=color(90,50,50);var c2=color(180,90,50);setGradient(x_trans-(quad_width/2)+i, skyHeight+93-j,quad_width,5,c1,c2,2);}function drawCicle(x_trans,angle,c1,c2,c3,i)
{push();noStroke();fill(c1,c2,c3);translate(x_trans-i+7,skyHeight+70+i*3);rotate(angle);arc(0,0,50,50, 0, PI/2);pop();
}function drawCicle_all(x_trans)
{for(var i=0;i<8;i++){drawCicle(x_trans+quad_width-8,24.5,100,10,10,i);drawCicle(x_trans+quad_width-8,-2.2,130,110,90,i);drawCicle(x_trans+quad_width-8,1,70,20,10,i);drawCicle(x_trans+quad_width-8,-3.5,200,160,80,i);}stroke(50,10,10);fill(140,100,50);ellipse(x_trans+60,skyHeight+95,50,50);fill(80,60,20);ellipse(x_trans+60,skyHeight+95,35,35);
}function drawWuYan4()
{for(var x_trans=50;x_trans<Width;x_trans++){drawPIdwon_shadow(x_trans+10,10);drawPIdwon(x_trans);for(var i=0;i<5;i++){yp=i*5;drawquad(i,yp,x_trans);}drawCicle_all(x_trans);x_trans=x_trans+120;}}function YinxingTree()
{push();drawtree(220,180,0,-20,20,random(0.6));drawtree(120,60,0,-100,100,random(0.01));drawtree(120,60,0,-50,160,random(0.01));drawtree(180,160,0,40,160,random(0.05));drawtree(200,100,0,-20,100,random(1));drawtree(200,160,0,0,120,random(0.5));drawtree(220,160,0,55,160,random(0.1));drawtree(240,200,0,50,100,random(0.3));drawtree(240,200,0,50,180,random(0.3));drawtree(240,200,0,80,190,random(1));drawtree(220,180,0,-50,80,random(0.1));translate(150,90);drawtree(220,180,0,-50,150,random(0.5));translate(-100,-150);drawtree(240,200,120,-100,100,random(0.01));pop();
}function drawtree(c1,c2,c3,pos_x,pos_y,pos_angle)
{push();rotate(pos_angle);var trans_x;var trans_y;var trans_angle;fill(c1,c2,c3);for(var i=0;i<20;i++){trans_x=random(50);trans_y=random(20);trans_angle=random(-0.5);push();translate(trans_x,trans_y);rotate(trans_angle);drawYinXing(pos_x,pos_y);pop();}pop();}function drawYinXing(pos_x,pos_y){stroke(200,150,60);push();translate(pos_x, pos_y);rotate(0.0);arc(0, 0, 30, 30, 0, PI/2);pop();}function drawsky(){var c1 = color(90,150,205);var c2 = color(190,200,220);noStroke();setGradient(0, 0, Width, skyHeight,c1,c2,1);}function setGradient(x, y, w, h, c1, c2,axis) {noFill();if (axis == Y_AXIS) {  // Top to bottom gradientfor (var i = y; i <= y+h; i++) {var inter = map(i, y, y+h, 0, 1);var c = lerpColor(c1, c2, inter);stroke(c);line(x, i, x+w, i);}}  else if (axis == X_AXIS) {  // Left to right gradientfor (var k = x; k <= x+w; k++) {var interk = map(k, x, x+w, 0, 1);var ck = lerpColor(c1, c2, interk);stroke(ck);line(k, y, k, y+h);}}}

代码结构解析

1.背景：
其实画背景还挺简单的，基本物体就是红墙，屋檐，银杏树，天空。
天空是渐变的，用了一个函数，p5官网里面也有：

function drawsky(){var c1 = color(90,150,205);var c2 = color(190,200,220);noStroke();setGradient(0, 0, Width, skyHeight,c1,c2,1);}function setGradient(x, y, w, h, c1, c2,axis) {noFill();if (axis == Y_AXIS) {  // Top to bottom gradientfor (var i = y; i <= y+h; i++) {var inter = map(i, y, y+h, 0, 1);var c = lerpColor(c1, c2, inter);stroke(c);line(x, i, x+w, i);}}  else if (axis == X_AXIS) {  // Left to right gradientfor (var k = x; k <= x+w; k++) {var interk = map(k, x, x+w, 0, 1);var ck = lerpColor(c1, c2, interk);stroke(ck);line(k, y, k, y+h);}}}

红墙就不细说了，直接看屋檐，屋檐还稍微有点东西。观察故宫屋檐结构之后发现，故宫这样的建筑简直太有规律可循了！你只要生成一个基本元，接下来的就只用循环生成就可以。我们主要来看看圆木那一块怎么实现。
圆木那里其实还挺麻烦，主要是有光的影响，圆木被分为三个面：受光面，反光面，阴影面，直接用一个圆肯定解决不了，我想了一个办法，用三个扇形就可以区分三个面。
具体代码：

function drawCicle(x_trans,angle,c1,c2,c3,i)
{push();noStroke();fill(c1,c2,c3);translate(x_trans-i+7,skyHeight+70+i*3);rotate(angle);arc(0,0,50,50, 0, PI/2);pop();
}function drawCicle_all(x_trans)
{for(var i=0;i<8;i++){drawCicle(x_trans+quad_width-8,24.5,100,10,10,i);drawCicle(x_trans+quad_width-8,-2.2,130,110,90,i);drawCicle(x_trans+quad_width-8,1,70,20,10,i);drawCicle(x_trans+quad_width-8,-3.5,200,160,80,i);}stroke(50,10,10);fill(140,100,50);ellipse(x_trans+60,skyHeight+95,50,50);fill(80,60,20);ellipse(x_trans+60,skyHeight+95,35,35);
}

还有瓦片上的阴影，也用了渐变过渡，这里就不贴代码了。

银杏树
一开始对银杏树没什么头绪，观察了好几棵学校里的银杏，在大风刮过之时，金黄树叶在风中颤抖摇晃，我突然有了灵感——色块堆积。我可以不用准准确确的画出这棵树长啥样，我只需要保证它在运动中是符合这棵树的逻辑的，那么这棵树就是成功的。
下面贴上代码：

function YinxingTree()
{push();drawtree(220,180,0,-20,20,random(0.6));drawtree(120,60,0,-100,100,random(0.01));drawtree(120,60,0,-50,160,random(0.01));drawtree(180,160,0,40,160,random(0.05));drawtree(200,100,0,-20,100,random(1));drawtree(200,160,0,0,120,random(0.5));drawtree(220,160,0,55,160,random(0.1));drawtree(240,200,0,50,100,random(0.3));drawtree(240,200,0,50,180,random(0.3));drawtree(240,200,0,80,190,random(1));drawtree(220,180,0,-50,80,random(0.1));translate(150,90);drawtree(220,180,0,-50,150,random(0.5));translate(-100,-150);drawtree(240,200,120,-100,100,random(0.01));pop();
}function drawtree(c1,c2,c3,pos_x,pos_y,pos_angle)
{push();rotate(pos_angle);var trans_x;var trans_y;var trans_angle;fill(c1,c2,c3);for(var i=0;i<20;i++){trans_x=random(50);trans_y=random(20);trans_angle=random(-0.5);push();translate(trans_x,trans_y);rotate(trans_angle);drawYinXing(pos_x,pos_y);pop();}pop();}function drawYinXing(pos_x,pos_y){stroke(200,150,60);push();translate(pos_x, pos_y);rotate(0.0);arc(0, 0, 30, 30, 0, PI/2);pop();}

大量使用radom可以让这棵树更自然。

2.动画主角——猫
这里我先对猫进行了一些处理——低多边形处理。
吸取了第一个实验的教训，这次我先设置了一个中心点，然后在根据这个点扩充出有关猫的肢干总共12个点，然后画三角形，形成一个没有四肢，没有尾巴的橘猫。

尾巴用了贝塞尔曲线，坐标也跟中心点关联。
猫的四肢是运动视觉的关键！！！动画之所以能动是因为有承上启下的连续性动作。猫行走从侧面看过去就是两腿相互交叉变换。所以在写动画逻辑之前你需要先画出关键帧状态。
关键帧状态确定了就可开始着手动画逻辑：首先视觉上我们先要营造出猫在原地踏步的感觉。我们有两个关键帧状态，所以可以运用模运算，在运动的中心坐标基础上模2，结果对应两个状态。
附上代码：

function feetControl(x,y){if(x%2==0){rect(x-(cat_scale)/10,y-8,(cat_scale)/10,(cat_scale)*1/3+8);    }else{quad(x,y-10,x-(cat_scale)/10,y-10,x-(cat_scale)/10+(cat_scale/10),y+(cat_scale)*1/3,x+(cat_scale/10),y+(cat_scale)*1/3);quad(x,y-15,x-(cat_scale)/10,y-15,x-(cat_scale)/10-(cat_scale/5),y+(cat_scale)*1/3,x-(cat_scale/5),y+(cat_scale)*1/3);}}

至此，动画完成。

手绘与码绘的对比

在动画这个应用上，其实两者各有千秋。手绘能做到画面更加精致有更多细节，更能体现质感，但同时，它又太过费时。而码绘在运动这一方面有着得天独厚的优势，它能更平滑的完成动画操作。

发现的问题

码绘在建立场景的过程中，发现对于环境色这一概念，几乎还是一个空白领域。