/// <summary>
/// A streak of lightning is drawn simply by piecing together a long string of small line segments,
/// each of which is slightly rotated.
/// </summary>
private void DrawLightningStreak(LineBatch lineBatch, Color color, Vector2 start, Vector2 end, int numSegments,
float deviation)
{
Random randomGen = new Random();
Vector2 disp = end - start;
Vector2 unitDisp = Vector2.Normalize(disp);
Vector2 stepVector = unitDisp * disp.Length() / (float)numSegments;
Vector2 perpVec = new Vector2(-stepVector.Y, stepVector.X);
perpVec.Normalize();
Vector2 startPoint = start;
Vector2 endPoint = new Vector2();
for (int i = 0; i < numSegments; ++i)
{
endPoint = start + stepVector * (i + 1);
// If this is an intermediate segment, apply an offset perpendicular to the line connecting start to end.
if (i < numSegments - 1)
{
float random = (float)randomGen.NextDouble();
float offset = (random >= 0.5f ? 1 : -1) * random * deviation;
endPoint += perpVec * offset;
}
lineBatch.DrawLine(startPoint, endPoint, color);
startPoint = endPoint;
}
}
/// <summary>
/// Draws the grid, showing the springs connecting neighboring nodes as line segments. The color of each
/// line segment is interpolated linearly between dimColor and brightColor depending on the length
/// of the segment.
/// </summary>
public void Draw(LineBatch lineBatch, Color dimColor, Color brightColor)
{
float dx = (bounds.Right - bounds.Left) / gridSize;
float dy = (bounds.Bottom - bounds.Top) / gridSize;
Vector4 vecDimColor = new Vector4(dimColor.R, dimColor.G, dimColor.B, dimColor.A);
Vector4 vecBrightColor = new Vector4(brightColor.R, brightColor.G, brightColor.B, brightColor.A);
for (int x = 0; x < gridSize; ++x)
{
for (int y = 0; y < gridSize; ++y)
{
if (x < gridSize - 1)
{
float lineLength = (grid[x + 1, y].Position - grid[x, y].Position).Length();
float t = (lineLength - dx) / (5 * (float)Math.Sqrt(2) * dx);
Vector4 modulatedColorVec = Vector4.Lerp(vecDimColor, vecBrightColor, t);
Color modulatedColor = new Color((byte)modulatedColorVec.X, (byte)modulatedColorVec.Y, (byte)modulatedColorVec.Z,
(byte)modulatedColorVec.W);
lineBatch.DrawLine(grid[x, y].Position, grid[x + 1, y].Position, modulatedColor);
}
if (y < gridSize - 1)
{
float lineLength = (grid[x, y + 1].Position - grid[x, y].Position).Length();
float t = (lineLength - dy) / (5 * (float)Math.Sqrt(2) * dx);
Vector4 modulatedColorVec = Vector4.Lerp(vecDimColor, vecBrightColor, t);
Color modulatedColor = new Color((byte)modulatedColorVec.X, (byte)modulatedColorVec.Y, (byte)modulatedColorVec.Z,
(byte)modulatedColorVec.W);
lineBatch.DrawLine(grid[x, y].Position, grid[x, y + 1].Position, modulatedColor);
}
}
}
}