wolf_dart/lib/features/renderer/raycast_painter.dart

import 'dart:math' as math;

import 'package:flutter/material.dart';
import 'package:wolf_dart/classes/linear_coordinates.dart';
import 'package:wolf_dart/classes/matrix.dart';
import 'package:wolf_dart/features/renderer/color_palette.dart';

class RaycasterPainter extends CustomPainter {
  final Matrix<int> map;
  final List<Matrix<int>> textures;
  final LinearCoordinates player;
  final double playerAngle;
  final double fov;

  RaycasterPainter({
    required this.map,
    required this.textures,
    required this.player,
    required this.playerAngle,
    required this.fov,
  });

  @override
  void paint(Canvas canvas, Size size) {
    // 1. Draw Ceiling & Floor
    canvas.drawRect(
      Rect.fromLTWH(0, 0, size.width, size.height / 2),
      Paint()..color = Colors.blueGrey[900]!,
    );
    canvas.drawRect(
      Rect.fromLTWH(0, size.height / 2, size.width, size.height / 2),
      Paint()..color = Colors.brown[900]!,
    );

    int screenWidth = size.width.toInt();

    // 2. Camera Plane Setup
    // Direction vector of the player
    double dirX = math.cos(playerAngle);
    double dirY = math.sin(playerAngle);

    // The camera plane is perpendicular to the direction vector.
    // Multiplying by tan(fov/2) scales the plane to match our field of view.
    double planeX = -dirY * math.tan(fov / 2);
    double planeY = dirX * math.tan(fov / 2);

    for (int x = 0; x < screenWidth; x++) {
      // Calculate where on the camera plane this ray passes (-1 is left edge, 1 is right edge)
      double cameraX = 2 * x / screenWidth - 1.0;
      double rayDirX = dirX + planeX * cameraX;
      double rayDirY = dirY + planeY * cameraX;

      // Current map box we are in
      int mapX = player.x.toInt();
      int mapY = player.y.toInt();

      // Length of ray from current position to next x or y-side
      double sideDistX;
      double sideDistY;

      // Length of ray from one x or y-side to next x or y-side
      double deltaDistX = (rayDirX == 0)
          ? double.infinity
          : (1.0 / rayDirX).abs();
      double deltaDistY = (rayDirY == 0)
          ? double.infinity
          : (1.0 / rayDirY).abs();
      double perpWallDist;

      // Direction to step in x or y direction (+1 or -1)
      int stepX;
      int stepY;

      bool hit = false;
      // 0 for North/South (vertical) walls, 1 for East/West (horizontal) walls
      int side = 0;
      int hitWallId = 0;

      // Calculate step and initial sideDist
      if (rayDirX < 0) {
        stepX = -1;
        sideDistX = (player.x - mapX) * deltaDistX;
      } else {
        stepX = 1;
        sideDistX = (mapX + 1.0 - player.x) * deltaDistX;
      }
      if (rayDirY < 0) {
        stepY = -1;
        sideDistY = (player.y - mapY) * deltaDistY;
      } else {
        stepY = 1;
        sideDistY = (mapY + 1.0 - player.y) * deltaDistY;
      }

      // 3. The True DDA Loop
      while (!hit) {
        // Jump to next map square, either in x-direction, or in y-direction
        if (sideDistX < sideDistY) {
          sideDistX += deltaDistX;
          mapX += stepX;
          side = 0;
        } else {
          sideDistY += deltaDistY;
          mapY += stepY;
          side = 1;
        }

        // Check bounds and wall collisions
        if (mapY < 0 ||
            mapY >= map.length ||
            mapX < 0 ||
            mapX >= map[0].length) {
          hit = true;
          perpWallDist = 20.0; // Out of bounds fallback
        } else if (map[mapY][mapX] > 0) {
          hit = true;
          hitWallId = map[mapY][mapX];
        }
      }

      // Calculate distance projected on camera direction (No fisheye effect!)
      if (side == 0) {
        perpWallDist = (sideDistX - deltaDistX);
      } else {
        perpWallDist = (sideDistY - deltaDistY);
      }

      // 4. Calculate exact wall hit coordinate for textures
      double wallX;
      if (side == 0) {
        wallX = player.y + perpWallDist * rayDirY;
      } else {
        wallX = player.x + perpWallDist * rayDirX;
      }
      wallX -= wallX.floor(); // Get just the fractional part (0.0 to 0.99)

      _drawTexturedColumn(
        canvas,
        x,
        perpWallDist,
        wallX,
        side,
        size,
        hitWallId,
        textures,
      );
    }
  }

  void _drawTexturedColumn(
    Canvas canvas,
    int x,
    double distance,
    double wallX,
    int side,
    Size size,
    int hitWallId,
    List<Matrix<int>> textures,
  ) {
    if (distance <= 0.01) distance = 0.01;

    double wallHeight = size.height / distance;
    int drawStart = ((size.height / 2) - (wallHeight / 2)).toInt();

    // 1. PERFECT TEXTURE MAPPING
    // Wolf3D stores textures in pairs. Even = N/S (Light), Odd = E/W (Dark).
    int texNum = ((hitWallId - 1) * 2).clamp(0, textures.length - 2);

    if (hitWallId >= 90) {
      texNum = 98; // 98 is the canonical index for the Wood Door in VSWAP
      // Optional: Doors don't usually have a dark E/W variant, so we don't add +1 for side
    } else {
      // Standard wall texture pairing
      texNum = ((hitWallId - 1) * 2).clamp(0, textures.length - 2);
      if (side == 1) texNum += 1;
    }

    int texX = (wallX * 64).toInt().clamp(0, 63);

    if (side == 0 && math.cos(playerAngle) > 0) texX = 63 - texX;
    if (side == 1 && math.sin(playerAngle) < 0) texX = 63 - texX;

    double startY = drawStart.toDouble();
    double stepY = wallHeight / 64.0;

    for (int ty = 0; ty < 64; ty++) {
      int colorByte = textures[texNum][texX][ty];

      // 2. NO MORE SHADOW MATH
      // Because we selected the correct dark texture above, we just draw the raw color!
      Color pixelColor = ColorPalette.vga[colorByte];

      double endY = startY + stepY;

      if (endY > 0 && startY < size.height) {
        canvas.drawLine(
          Offset(x.toDouble(), startY),
          Offset(x.toDouble(), endY),
          Paint()
            ..color = pixelColor
            ..strokeWidth = 1.1,
        );
      }

      startY += stepY;
    }
  }

  @override
  bool shouldRepaint(covariant RaycasterPainter oldDelegate) {
    return oldDelegate.player != player ||
        oldDelegate.playerAngle != playerAngle;
  }
}