尝试制作一个简单的欧拉公式

Question

https://gamedev.stackexchange.com/questions/13178/why-is-my-velocity-decaying

我正在使用该线程中的建议答案来为我的粒子系统尝试一个基本的物理公式。出于某种原因，尽管它甚至根本不再移动我的粒子。有人能比我更擅长数学吗？可以看看我的公式是否正确吗？这些东西让我头疼，但我想对我的粒子施加一些重力。

Particle.cs

using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Game1
{
    public class Particle
    {
        public Texture2D Texture { get; set; }
        public Vector2 Position { get; set; }
        public Vector2 Velocity { get; set; }
        public float Mass = 1.0f;
        public Vector2 Acceleration { get; set; }
        public float Angle { get; set; }
        public float AngularVelocity { get; set; }
        public Color Color { get; set; }
        public float Size { get; set; }
        public int TTL { get; set; } //Time to live

        public Particle(Texture2D texture, Vector2 position, Vector2 velocity, Vector2 acceleration, float angle, float angularVelocity, Color color, float size, int ttl)
        {
            Texture = texture;
            Position = position;
            Velocity = velocity;
            Acceleration = acceleration;
            Angle = angle;
            AngularVelocity = angularVelocity;
            Color = color;
            Size = size;
            TTL = ttl;
        }

        public void Update(GameTime gameTime)
        {
            var dt = gameTime.ElapsedGameTime.TotalSeconds;

            TTL--;
            var t = Vector2.Multiply(Velocity, (float)dt);
            var r = Vector2.Multiply(Acceleration, 0.5f);
            var q = Vector2.Multiply(t + r, (float)dt);
            var f = Vector2.Multiply(q, (float)dt);

            Position += f;
            Velocity += Vector2.Multiply(Acceleration, (float)dt);
        }

        public void Draw(SpriteBatch spriteBatch)
        {
            Rectangle sourceRectangle = new Rectangle(0, 0, Texture.Width, Texture.Height);
            Vector2 origin = new Vector2(Texture.Width / 2, Texture.Height / 2);
            spriteBatch.Draw(Texture, Position, sourceRectangle, Color, Angle, origin, Size, SpriteEffects.None, 0f);
        }
    }
}

创建粒子

private Particle GenerateNewParticle(GameTime gameTime)
        {
            Texture2D texture = textures[random.Next(textures.Count)];
            Vector2 position = EmitterLocation;

            Vector2 velocity = new Vector2(1f * (float)(random.NextDouble() * 2 - 1), (1f * (float)(random.NextDouble() * 2 - 1)));
            Vector2 acceleration = new Vector2(20f, 20f);
            float angle = 0;
            float angularVelocity = 0.1f * (float)(random.NextDouble() * 2 - 1);
            Color color = new Color((float)random.NextDouble(), (float)random.NextDouble(), (float)random.NextDouble());
            float size = (float)random.NextDouble();
            int ttl = 20 + random.Next(40);

            return new Particle(texture, position, velocity, acceleration, angle, angularVelocity, color, size, ttl);
        }

Answer 1

看来您输入的 q 项不正确。运算符优先级将首先进行乘法运算，然后进行加法运算。要实现您引用的方程式，

q 应该是 Vector2.Multiply(r, (float)dt);

那么您对 Position 的更新需要变成 Position += (t+f);

尝试制作一个简单的欧拉公式

Trying to make a simple Euler Formula

c#

physics

monogame

particle-system