编辑：GameDev SE 上的问题链接： https ://gamedev.stackexchange.com/questions/51656/implementing-water-effects-splashes-into-xna-4-0-game
我正在创建一个 2D XNA 游戏，并遇到了一个关于向 XNA 游戏添加水效果（飞溅）的教程，但是在将它实施到我的游戏中后，我无法缩小它。目前它占据了整个屏幕。
水类看起来像这样
class Water
{
struct WaterColumn
{
public float TargetHeight;
public float Height;
public float Speed;
public void Update(float dampening, float tension)
{
float x = TargetHeight - Height;
Speed += tension * x - Speed * dampening;
Height += Speed;
}
}
PrimitiveBatch pb;
WaterColumn[] columns = new WaterColumn[201];
static Random rand = new Random();
public float Tension = 0.025f;
public float Dampening = 0.025f;
public float Spread = 0.25f;
RenderTarget2D metaballTarget, particlesTarget;
SpriteBatch spriteBatch;
AlphaTestEffect alphaTest;
Texture2D particleTexture;
private float Scale { get { return spriteBatch.GraphicsDevice.Viewport.Width / (columns.Length - 1f); } }
List<Particle> particles = new List<Particle>();
class Particle
{
public Vector2 Position;
public Vector2 Velocity;
public float Orientation;
public Particle(Vector2 position, Vector2 velocity, float orientation)
{
Position = position;
Velocity = velocity;
Orientation = orientation;
}
}
public Water(GraphicsDevice device, Texture2D particleTexture)
{
pb = new PrimitiveBatch(device);
this.particleTexture = particleTexture;
spriteBatch = new SpriteBatch(device);
metaballTarget = new RenderTarget2D(device, device.Viewport.Width, device.Viewport.Height);
particlesTarget = new RenderTarget2D(device, device.Viewport.Width, device.Viewport.Height);
alphaTest = new AlphaTestEffect(device);
alphaTest.ReferenceAlpha = 175;
var view = device.Viewport;
alphaTest.Projection = Matrix.CreateTranslation(-0.5f, -0.5f, 0) *
Matrix.CreateOrthographicOffCenter(0, view.Width, view.Height, 0, 0, 1);
for (int i = 0; i < columns.Length; i++)
{
columns[i] = new WaterColumn()
{
Height = 240,
TargetHeight = 240,
Speed = 0
};
}
}
// Returns the height of the water at a given x coordinate.
public float GetHeight(float x)
{
if (x < 0 || x > 800)
return 240;
return columns[(int)(x / Scale)].Height;
}
void UpdateParticle(Particle particle)
{
const float Gravity = 0.3f;
particle.Velocity.Y += Gravity;
particle.Position += particle.Velocity;
particle.Orientation = GetAngle(particle.Velocity);
}
public void Splash(float xPosition, float speed)
{
int index = (int)MathHelper.Clamp(xPosition / Scale, 0, columns.Length - 1);
for (int i = Math.Max(0, index - 0); i < Math.Min(columns.Length - 1, index + 1); i++)
columns[index].Speed = speed;
CreateSplashParticles(xPosition, speed);
}
private void CreateSplashParticles(float xPosition, float speed)
{
float y = GetHeight(xPosition);
if (speed > 120)
{
for (int i = 0; i < speed / 8; i++)
{
Vector2 pos = new Vector2(xPosition, y) + GetRandomVector2(40);
Vector2 vel = FromPolar(MathHelper.ToRadians(GetRandomFloat(-150, -30)), GetRandomFloat(0, 0.5f * (float)Math.Sqrt(speed)));
CreateParticle(pos, vel);
}
}
}
private void CreateParticle(Vector2 pos, Vector2 velocity)
{
particles.Add(new Particle(pos, velocity, 0));
}
private Vector2 FromPolar(float angle, float magnitude)
{
return magnitude * new Vector2((float)Math.Cos(angle), (float)Math.Sin(angle));
}
private float GetRandomFloat(float min, float max)
{
return (float)rand.NextDouble() * (max - min) + min;
}
private Vector2 GetRandomVector2(float maxLength)
{
return FromPolar(GetRandomFloat(-MathHelper.Pi, MathHelper.Pi), GetRandomFloat(0, maxLength));
}
private float GetAngle(Vector2 vector)
{
return (float)Math.Atan2(vector.Y, vector.X);
}
public void Update()
{
for (int i = 0; i < columns.Length; i++)
columns[i].Update(Dampening, Tension);
float[] lDeltas = new float[columns.Length];
float[] rDeltas = new float[columns.Length];
// do some passes where columns pull on their neighbours
for (int j = 0; j < 8; j++)
{
for (int i = 0; i < columns.Length; i++)
{
if (i > 0)
{
lDeltas[i] = Spread * (columns[i].Height - columns[i - 1].Height);
columns[i - 1].Speed += lDeltas[i];
}
if (i < columns.Length - 1)
{
rDeltas[i] = Spread * (columns[i].Height - columns[i + 1].Height);
columns[i + 1].Speed += rDeltas[i];
}
}
for (int i = 0; i < columns.Length; i++)
{
if (i > 0)
columns[i - 1].Height += lDeltas[i];
if (i < columns.Length - 1)
columns[i + 1].Height += rDeltas[i];
}
}
foreach (var particle in particles)
UpdateParticle(particle);
particles = particles.Where(x => x.Position.X >= 0 && x.Position.X <= 800 && x.Position.Y - 5 <= GetHeight(x.Position.X)).ToList();
}
public void DrawToRenderTargets()
{
GraphicsDevice device = spriteBatch.GraphicsDevice;
device.SetRenderTarget(metaballTarget);
device.Clear(Color.Transparent);
// draw particles to the metaball render target
spriteBatch.Begin(0, BlendState.Additive);
foreach (var particle in particles)
{
Vector2 origin = new Vector2(particleTexture.Width, particleTexture.Height) / 2f;
spriteBatch.Draw(particleTexture, particle.Position, null, Color.White, particle.Orientation, origin, 2f, 0, 0);
}
spriteBatch.End();
// draw a gradient above the water so the metaballs will fuse with the water's surface.
pb.Begin(PrimitiveType.TriangleList);
const float thickness = 20;
float scale = Scale;
for (int i = 1; i < columns.Length; i++)
{
Vector2 p1 = new Vector2((i - 1) * scale, columns[i - 1].Height);
Vector2 p2 = new Vector2(i * scale, columns[i].Height);
Vector2 p3 = new Vector2(p1.X, p1.Y - thickness);
Vector2 p4 = new Vector2(p2.X, p2.Y - thickness);
pb.AddVertex(p2, Color.White);
pb.AddVertex(p1, Color.White);
pb.AddVertex(p3, Color.Transparent);
pb.AddVertex(p3, Color.Transparent);
pb.AddVertex(p4, Color.Transparent);
pb.AddVertex(p2, Color.White);
}
pb.End();
// save the results in another render target (in particlesTarget)
device.SetRenderTarget(particlesTarget);
device.Clear(Color.Transparent);
spriteBatch.Begin(0, null, null, null, null, alphaTest);
spriteBatch.Draw(metaballTarget, Vector2.Zero, Color.White);
spriteBatch.End();
// switch back to drawing to the backbuffer.
device.SetRenderTarget(null);
}
public void Draw()
{
Color lightBlue = new Color(0.2f, 0.5f, 1f);
// draw the particles 3 times to create a bevelling effect
spriteBatch.Begin();
spriteBatch.Draw(particlesTarget, -Vector2.One, new Color(0.8f, 0.8f, 1f));
spriteBatch.Draw(particlesTarget, Vector2.One, new Color(0f, 0f, 0.2f));
spriteBatch.Draw(particlesTarget, Vector2.Zero, lightBlue);
spriteBatch.End();
// draw the waves
pb.Begin(PrimitiveType.TriangleList);
Color midnightBlue = new Color(0, 15, 40) * 0.9f;
lightBlue *= 0.8f;
float bottom = spriteBatch.GraphicsDevice.Viewport.Height;
float scale = Scale;
for (int i = 1; i < columns.Length; i++)
{
Vector2 p1 = new Vector2((i - 1) * scale, columns[i - 1].Height);
Vector2 p2 = new Vector2(i * scale, columns[i].Height);
Vector2 p3 = new Vector2(p2.X, bottom);
Vector2 p4 = new Vector2(p1.X, bottom);
pb.AddVertex(p1, lightBlue);
pb.AddVertex(p2, lightBlue);
pb.AddVertex(p3, midnightBlue);
pb.AddVertex(p1, lightBlue);
pb.AddVertex(p3, midnightBlue);
pb.AddVertex(p4, midnightBlue);
}
pb.End();
}
}
然后在 Game1.cs 我有以下 LoadContent 方法
protected override void LoadContent()
{
// Create a new SpriteBatch, which can be used to draw textures.
spriteBatch = new SpriteBatch(GraphicsDevice);
font = Content.Load<SpriteFont>("Font");
particleImage = Content.Load<Texture2D>("metaparticle");
backgroundImage = Content.Load<Texture2D>("sky");
rockImage = Content.Load<Texture2D>("rock");
water = new Water(GraphicsDevice, particleImage);
.
.
.
}
在我的更新方法中，我有以下内容（以及游戏的其他代码，我只是展示了水的部分）
protected override void Update(GameTime gameTime)
{
lastKeyState = keyState;
keyState = Keyboard.GetState();
lastMouseState = mouseState;
mouseState = Mouse.GetState();
water.Update();
Vector2 mousePos = new Vector2(mouseState.X, mouseState.Y);
// if the user clicked down, create a rock.
if (lastMouseState.LeftButton == ButtonState.Released && mouseState.LeftButton == ButtonState.Pressed)
{
rock = new Rock
{
Position = mousePos,
Velocity = (mousePos - new Vector2(lastMouseState.X, lastMouseState.Y)) / 5f
};
}
// update the rock if it exists
if (rock != null)
{
if (rock.Position.Y < 240 && rock.Position.Y + rock.Velocity.Y >= 240)
water.Splash(rock.Position.X, rock.Velocity.Y * rock.Velocity.Y * 5);
rock.Update(water);
if (rock.Position.Y > GraphicsDevice.Viewport.Height + rockImage.Height)
rock = null;
}
然后在 Draw 方法中我有以下内容（当活动枚举是 InGame 时）
case ActiveScreen.InGame:
water.DrawToRenderTargets();
level.Draw(gameTime, spriteBatch);
DrawHud();
spriteBatch.Begin();
spriteBatch.Draw(backgroundImage, Vector2.Zero, Color.White);
if (rock != null)
rock.Draw(spriteBatch, rockImage);
spriteBatch.End();
water.Draw();
break;
我的问题是这显然占据了整个屏幕。我知道为什么它占据了整个屏幕，但我不知道如何缩小它并将其设置在游戏中的固定位置。如果有人能通读这篇文章并指导我如何成功地缩小规模，我将不胜感激。