using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Graphics; using System; namespace SemiColinGames { class LinesOfSight { const int numEdgeVertices = 60; // coneVertices[0] is the eye position; the rest are the edge vertices. VertexPositionColor[] coneVertices = new VertexPositionColor[numEdgeVertices + 1]; Color color = Color.FromNonPremultiplied(new Vector4(0, 0, 1, 0.6f)); // The number of total triangles drawn is one less than the number of edge points. int[] indices = new int[(numEdgeVertices - 1) * 3]; VertexBuffer vertexBuffer; IndexBuffer indexBuffer; public LinesOfSight(GraphicsDevice graphics) { vertexBuffer = new VertexBuffer( graphics, typeof(VertexPositionColor), numEdgeVertices * 3, BufferUsage.WriteOnly); indexBuffer = new IndexBuffer( graphics, typeof(int), indices.Length, BufferUsage.WriteOnly); } public void Update(Player player, AABB[] collisionTargets) { Vector2 eyePos = player.EyePosition; float visionRange = 150; float visionRangeSq = visionRange * visionRange; float fov = FMath.DegToRad(120); float fovStep = fov / (numEdgeVertices - 1); Vector2 ray = new Vector2(visionRange * player.Facing, 0); if (player.GetPose == Player.Pose.Stretching) { ray = ray.Rotate(player.Facing * FMath.DegToRad(-30)); } if (player.GetPose == Player.Pose.Crouching) { ray = ray.Rotate(player.Facing * FMath.DegToRad(30)); } coneVertices[0] = new VertexPositionColor(new Vector3(player.EyePosition, 0), color); for (int i = 0; i < numEdgeVertices; i++) { float angle = -fov / 2 + fovStep * i; Vector2 rotated = ray.Rotate(angle); Vector2 closestHit = Vector2.Add(eyePos, rotated); float hitTime = 1f; Vector2 halfTileSize = new Vector2(World.TileSize / 2.0f, World.TileSize / 2.0f); for (int j = 0; j < collisionTargets.Length; j++) { AABB box = collisionTargets[j]; if (Math.Abs(box.Position.X - player.Position.X) > visionRange + halfTileSize.X) { continue; } Vector2 delta = Vector2.Add(halfTileSize, Vector2.Subtract(box.Position, eyePos)); if (delta.LengthSquared() > visionRangeSq) { continue; } Hit? maybeHit = box.IntersectSegment(eyePos, rotated); if (maybeHit != null) { Hit hit = maybeHit.Value; if (hit.Time < hitTime) { hitTime = hit.Time; closestHit = hit.Position; } } } float tint = 0.6f - hitTime / 2; Color tinted = Color.FromNonPremultiplied(new Vector4(0, 0, 1, tint)); coneVertices[i + 1] = new VertexPositionColor(new Vector3(closestHit, 0), tinted); } } public void Draw(Player player, AABB[] collisionTargets, GraphicsDevice graphics, BasicEffect lightingEffect) { for (int i = 0; i < numEdgeVertices - 1; i++) { indices[i * 3] = 0; indices[i * 3 + 1] = i + 1; indices[i * 3 + 2] = i + 2; } vertexBuffer.SetData(coneVertices); indexBuffer.SetData(indices); graphics.SetVertexBuffer(vertexBuffer); graphics.Indices = indexBuffer; foreach (EffectPass pass in lightingEffect.CurrentTechnique.Passes) { pass.Apply(); graphics.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, indices.Length / 3); } } } }