public override void Update(GameTime gameTime)
{
cCollisionMap cm = PrimalDevistation.Instance.Level.CollisionMap;
float fpOldX, fpOldY, fpNewX, fpNewY;
int oldX, oldY, newX, newY;
// Update the particles in a fountain type of way
for (int i = 0; i < _maxParticles; i++)
{
cCPUParticle p = _particles[i];
p._velX += PrimalDevistation.GRAVITY.X;
p._velY += PrimalDevistation.GRAVITY.Y;
fpOldX = _pointVertices[i].position.X;
fpOldY = _pointVertices[i].position.Y;
fpNewX = fpOldX + p._velX;
fpNewY = fpOldY + p._velY;
oldX = (int)fpOldX;
oldY = (int)fpOldY;
newX = (int)fpNewX;
newY = (int)fpNewY;
// If we have actually moved a pixel in the last frame (could have been less!)
if (oldX != newX)
{
// If we collide at this new X position we need to rebound
if (cm.CheckCollision(newX, oldY))
{
p._velX = -p._velX * 0.5f;
fpNewX = fpOldX;
}
}
// If we have actually moved a pixel in the last frame (could have been less!)
if (oldY != newY)
{
// If we collide at this new X position we need to rebound
if (cm.CheckCollision(oldX, newY))
{
p._velY = -p._velY * 0.5f;
fpNewY = fpOldY;
}
}
// Finally set the new position
_pointVertices[i].position.X = fpNewX;
_pointVertices[i].position.Y = fpNewY;
}
}
protected override void LoadGraphicsContent(bool loadAllContent)
{
if (loadAllContent)
{
ContentManager cm = PrimalDevistation.Instance.CM;
GraphicsDevice gd = GraphicsDevice;
Random r = new Random();
// Load the standard point sprite render effect
_renderEffect = cm.Load <Effect>(@"Shaders/PointSpriteRender");
_texture = cm.Load <Texture2D>(@"Sprites/particle2x2");
// Create the vertex buffer
_vertexBuffer = new VertexBuffer(gd, _maxParticles * PointVertex.Size, ResourceUsage.Points | ResourceUsage.WriteOnly, ResourceManagementMode.Automatic);
// Create the declaration
_vertexDeclaration = new VertexDeclaration(gd, PointVertex.Elements);
// init the points
_pointVertices = new PointVertex[_maxParticles];
_particles = new cCPUParticle[_maxParticles];
for (int i = 0; i < _maxParticles; i++)
{
_pointVertices[i] = new PointVertex();
_pointVertices[i].position = new Vector3(-100, -100, 0);
_pointVertices[i].color = _colors[r.Next(0, _colors.Length)].ToVector4();
_pointVertices[i].pointSize = 2;
_particles[i] = new cCPUParticle();
}
// Create a matrix to convert from pixel coordinates to clip space
// So, before transformation, the screen boundaries go from 0 to (say) 640 horizontally,
// and 0 to (say) 480 vertically. After transformation, they go from -1 to 1 horizontally,
// and -1 to 1 vertically. Note in pixel coordinates, increasing Y values are further down
// the screen, while in clip space, increasing Y values are further up the screen -- so there
// is a Y scaling factor of -1.
float viewportWidth = (float)gd.Viewport.Width;
float viewportHeight = (float)gd.Viewport.Height;
float scaleX = 1.0f / (viewportWidth / 2);
float scaleY = 1.0f / (viewportHeight / 2);
_proj = Matrix.CreateScale(scaleX, scaleY, 1) *
Matrix.CreateScale(1, -1, 1) *
Matrix.CreateTranslation(-1, 1, 0);
}
}
