Solar Eclipe - Pacman Style!
Funny Eclipse Pick - reminded me of Pac-man. Miss those good old days..
XNA Sphere
As mentioned in the previous post, this is bout creating a sphere in XNA.
I forgot to mention in my previous post, that these are useful for visualizing stuff in 3d world, this actually doesn't create surface - just lines.
I'll be using the Circle created in before to setup my sphere.
The funny thing about a sphere is that projection on any plane will always be a circle.Hence, when creating the circles we ensure that they lie on the circumference
Refer image below for clarity:
Here is the complete code:
Screen shots:
Pretty Ok for debugging I think.
NFS: I get confused with sin and cos!Hope you've learnt something in the future!
I forgot to mention in my previous post, that these are useful for visualizing stuff in 3d world, this actually doesn't create surface - just lines.
I'll be using the Circle created in before to setup my sphere.
The funny thing about a sphere is that projection on any plane will always be a circle.Hence, when creating the circles we ensure that they lie on the circumference
Refer image below for clarity:
Here is the complete code:
//Generic Sphere for XNA Debugging / Visualizing.
//This is just a set of lines - no surface
//Author: Vikram N [ makubex ]
//Blog: 8bitmemories.blogspot.com
public class Sphere
{ //Color of the verttices
Color _VertexColor;
//List of Circles that make up the sphere
//Refer to post on Circles
List<Circle> _Verticals;
List<Circle> _Horizontals;
//Save original position
//Becomes easy to transform the sphere
Vector3[] _HBasePositions;
Vector3[] _VBasePositions;
//Main game reference
Game _Game;
BasicEffect _Effect;
//Not used
//NFS: May be useful someother day
Matrix _Transforms;
//Store pos, scale and rotation
//Only pos is useful. Others have not been implemented
//Rotation - no diff
//Scale - why dude.. create a new one with diff radius :P
Vector3 _Position, _Scale, _Rotation;
//Radius of the sphere
float _Radius;
public Vector3 Position
{get
{return _Position;
}
set
{_Position = value;
Transform();
}
}
public Vector3 Rotation
{get
{return _Rotation;
}
set
{_Rotation = value;
Transform();
}
}
public Vector3 Scale
{get
{return _Scale;
}
set
{_Scale = value;
Transform();
}
}
public Matrix Transforms
{get
{return _Transforms;
}
set
{_Transforms = value;
}
}
//No of circles to be used for creating the sphere
//Higher the number, better it looks
//10 seems to look nice :P
int LEVELS = 10;
//Constructor
public Sphere(Game game, Color color, float radius)
{_Game = game;
_Effect = new BasicEffect(_Game.GraphicsDevice, null);
_Effect.VertexColorEnabled = true;
_VertexColor = color;
_Transforms = Matrix.Identity;
_Radius = radius;
_Verticals = new List<Circle>();
_Horizontals = new List<Circle>();
Setup();
}
//Function to create circles
void Setup()
{float offset = _Radius / (float)LEVELS;
float rOffset = 90 / LEVELS;
//Add one on each side of the center
//For expln refer the blog - 8bitmemories.blogspot.com
for (int i = 0; i <= LEVELS; i++)
{ Circle tmpPos = new Circle(_Game, _VertexColor, _Radius * (float) Math.Cos(MathHelper.ToRadians(i*rOffset)));
tmpPos.Position = new Vector3(0, _Radius * (float)Math.Sin(MathHelper.ToRadians(i * rOffset)), 0);
Circle tmpNeg = new Circle(_Game, _VertexColor, _Radius * (float)Math.Cos(MathHelper.ToRadians(i * rOffset)));
tmpNeg.Position = new Vector3(0, -_Radius * (float)Math.Sin(MathHelper.ToRadians(i * rOffset)), 0);
_Verticals.Add(tmpPos);
_Verticals.Add(tmpNeg);
}
//Same logic but set rotation of 90 degrees on z axis
for (int i = 0; i <= LEVELS; i++)
{Circle tmpPos = new Circle(_Game, _VertexColor, _Radius * (float)Math.Cos(MathHelper.ToRadians(i * rOffset)));
tmpPos.Position = new Vector3(_Radius * (float)Math.Sin(MathHelper.ToRadians(i * rOffset)), 0, 0);
tmpPos.Rotation = new Vector3(0, 0, MathHelper.PiOver2);
Circle tmpNeg = new Circle(_Game, _VertexColor, _Radius * (float)Math.Cos(MathHelper.ToRadians(i * rOffset)));
tmpNeg.Position = new Vector3( -_Radius * (float)Math.Sin(MathHelper.ToRadians(i * rOffset)),0, 0);
tmpNeg .Rotation = new Vector3(0, 0, MathHelper.PiOver2);
_Horizontals.Add(tmpPos);
_Horizontals.Add(tmpNeg);
}
//Save original positions
//Useful for translation
_HBasePositions = _Horizontals.Select(x => x.Position).ToArray();
_VBasePositions = _Verticals.Select(x => x.Position).ToArray();
}
//Move the sphere
void Transform()
{//Not used
_Transforms = Matrix.CreateScale(_Scale) * Matrix.CreateFromYawPitchRoll(_Rotation.Y, _Rotation.X, _Rotation.Z) * Matrix.CreateTranslation(_Position);
//Use the base positions + translation value
for (int i = 0; i < _Verticals.Count; i++)
{_Verticals[i].Position = _VBasePositions[i] + _Position;
}
for (int i = 0; i < _Horizontals.Count; i++)
{_Horizontals[i].Position = _HBasePositions[i] + _Position;
}
}
//Draw spheres
public void Draw()
{//Draw horizontal and vertical circles
for (int i = 0; i < _Verticals.Count; i++)
{_Verticals[i].Draw();
}
for (int i = 0; i < _Horizontals.Count; i++)
{_Horizontals[i].Draw();
}
}
}
Screen shots:
Pretty Ok for debugging I think.
NFS: I get confused with sin and cos!Hope you've learnt something in the future!
Simple Circle in XNA
This post is about creating a simple circle in XNA using VertexPositionColor elements and LineStrip primitive.
Lets call our class Circle.
Members:
Properties:
Constants:
Constructor:
Setup Function:
Transform Function:
Draw Function:
//List of vertices
List<VertexPositionColor> _Vertices;
//Convert to array to avoid ToArray for every draw
VertexPositionColor[] _VertexArray;
//Color of the vertices
Color _VertexColor;
//Main game class
Game_Game;
BasicEffect _Effect;
//Transforms for the circle
Matrix _Transforms;
Vector3 _Position, _Scale, _Rotation;
//Radius of the circle
float _Radius;
Properties:
public Vector3 Position
{get{ return_Position; }set{_Position=value;Transform();}}
public Vector3 Rotation
{get{return_Rotation;}set{_Rotation=value;Transform();}}
public Vector3 Scale
{get{return_Scale;}set{_Scale=value;Transform();}}
public MatrixTransforms
{get{return_Transforms;}set{_Transforms=value;}}
//This indicates that every 5 degree
//a point on the cirumference will be added
//Ex: 360/5 = 72 points will be used
int DEGREE_INCREMENT = 5;
Constructor:
public Circle(Game game, Color color, float radius)
{_Game = game;
_Effect = new BasicEffect(_Game.GraphicsDevice, null);
_Effect.VertexColorEnabled = true;
_VertexColor = color;
_Transforms = Matrix.Identity;
_Radius = radius;
_Scale = Vector3.One;
_Vertices = new List<VertexPositionColor>();
Setup();
_VertexArray = _Vertices.ToArray();
}
Setup Function:
void Setup()
{//For each number of points : 360/ DEGREE_INCREMENT
for (int i = 0; i <= 360; i+= DEGREE_INCREMENT)
{VertexPositionColor tmp = new VertexPositionColor();
// X => R * Cos(Angle), Y = 0, Z => R * Sin(Angle)
tmp.Position = new Vector3(_Radius * (float)Math.Cos(MathHelper.ToRadians(i)), 0, _Radius * (float)Math.Sin(MathHelper.ToRadians(i)));
tmp.Color = _VertexColor;
_Vertices.Add(tmp);
}
}
Transform Function:
//Update transform when pos, rot, scale is changed
void Transform()
{_Transforms = Matrix.CreateScale(_Scale) *
Matrix.CreateFromYawPitchRoll(_Rotation.Y, _Rotation.X, _Rotation.Z) *
Matrix.CreateTranslation(_Position);
}
Draw Function:
public void Draw()
{//Tell the device we are sending Vertexpositioncolor elements
_Game.GraphicsDevice.VertexDeclaration = new VertexDeclaration(_Game.GraphicsDevice, VertexPositionColor.VertexElements);
_Effect.Begin();
foreach (EffectPass pass in _Effect.CurrentTechnique.Passes)
{pass.Begin();
//Set the world, view, projection matrices
_Effect.World = _Transforms;
_Effect.View = Camera.View;
_Effect.Projection = Camera.Projection;
//Draw primitive: n points => n-1 lines
_Game.GraphicsDevice.DrawUserPrimitives<VertexPositionColor>(PrimitiveType.LineStrip, _VertexArray, 0, _Vertices.Count - 1);
pass.End();
}
_Effect.End();
}
Screen shots with different Degree increments:
Next up - Sphere
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