水的方向 | JavaScript 程式專案

{"id":9005,"student_id":1470,"content":"setBackdrop(\"gray\");\nvar koding = createSprite({\n    x: 300,\n    y: 240,\n    scale: 0.2, // 1.2倍大\n    costumes: [\"1.svg\"]\n});\nvar vectorField = [];\nvar balls = [];\nfunction f(x, y){ //change this\n    //if(x*y == 0) return [x, y, 0];\n    var newX = -y;\n    var newY = x;\n    var abs = Math.sqrt( Math.pow(x - newX, 2) + Math.pow(y - newY, 2) );\n    if(abs != 0){\n        newX /= abs/10;\n        newY /= abs/10;\n    } else {\n        return [newX, newY, 0];\n    }\n    \n    return [newX, newY, abs];\n}\nvar oriVector, newVector;\n\nfunction getPoints(){\n    for(var i = -320; i \u003c 320; i+=5){\n        for(var j = -240; j \u003c 240; j += 5){\n            vectorField.push([i , j , f(i, j)[0], f(i, j)[1]]); \n        }\n    }\n    console.log(\"Fin\");\n}\n\nfunction drawVecs(){\n for(var i = 0; i \u003c vectorField.length; i++){\n        pen.drawLine(vectorField[i][0] + 320, vectorField[i][1] + 240, vectorField[i][2] + vectorField[i][0] + 320, vectorField[i][3] + vectorField[i][1] + 240);\n    }\n}\ngetPoints();\npen.size = 3;\npen.color = \"black\";\n\nforever(function(){\n    vectorField = [];\n    getPoints();\n    drawVecs();\n    koding.x += f(koding.x - 320, koding.y - 240)[0];\n    koding.y += f(koding.x - 320, koding.y - 240)[1];\n    //drawVecs();\n    if(balls.length \u003e 10){\n        balls.shift();\n    }\n    for(var j = 0; j \u003c balls.length; j++){\n        console.log(balls[j] + \" j : \" + j);\n        pen.drawCircle(balls[j].x, balls[j].y, 2);\n        balls[j].update();\n        if(balls[j].x \u003e 640 || balls[j].x \u003c 0 || balls[j].y \u003e 480 || balls[j].y \u003c 0){\n            balls.splice(j, 1);\n        }\n    }\n})\n\nwhen(\"mouseup\", function(){\n    balls.push({\n        x: cursor.x,\n        y: cursor.y,\n        update: function(){\n            this.x += f(this.x - 320, this.y - 240)[0];\n            this.y += f(this.x - 320, this.y - 240)[1]\n        },\n    });\n    \n})","created_at":"2017-03-01T20:52:04.729+08:00","updated_at":"2019-11-12T04:00:56.599+08:00","name":"水的方向","language":"javascript","screenshot":{"url":"https://cdn8.koding.school/uploads/project/screenshot/9005/8e368b7bbf3a05a6e0e5621974fc2709.jpg"},"parent_id":2,"plugin":"","description":null,"note":null,"status":"public","like_student_ids":[],"is_featured":false,"views":471,"hashid":"6rpsmn4","is_content_changed":false,"review_status":"unsubmitted","submitted_at":null,"reviewed_at":null,"advise":null,"is_deleted":false}