How can I add different height sizes to walls in a Java "windows' maze" project using the ray casting algorithm?

Ray Casting with Different Height Size

Problem

In a Java "windows' maze" project using the ray casting algorithm, all walls have the same height size. The goal is to create a version with different height sizes.

Solution

1. Add Height Information to the Map:

Add a third value to each cell in the map to represent the height of the wall in that cell. For example, pmap[y][x] = (color, distance, height).

2. Update Ray-Casting Algorithm:

• Check Z Value for Hit Detection: When checking for hits, include the height values to determine whether the ray has hit a wall of the correct height.
• Compute Projected Height: Calculate the projected height of the wall based on the distance from the ray to the hit point and the viewing angle.

• Adjust Rendering:

  • Variable Height Rendering: Use the projected height to adjust the scanline rendering for the wall, creating a 3D effect.
  • Topside Rendering: Check for hits on the back faces of walls and render the topside color from the last rendered y coordinate to the current one.

3. Consider Mouse Wheel Input:

Allow users to adjust the height of walls (in map editor mode) using the mouse wheel.

Detailed Code Snippets: Here is a snippet from the revised castRayInX function:

    // Check for hits on front or back wall based on direction
    boolean hit = false;
    Color c = null;
    int z = 0;
    if (slope > 0) {
        int firstX = ((eye.getX() / SQUARE_SIZE) + 1) * SQUARE_SIZE;
        for (int x = firstX; x < map[0].length * SQUARE_SIZE; x += SQUARE_SIZE) {
            int y = (int) (slope * (x - eye.getX()) + eye.getY());
            if (isOutside(x, y, Color.MAGENTA, this.showRayCastingX))
                break;
            c = colorAt(x, y);
            z = heightAt(x, y);
            if (c == null)
                c = colorAt(x, y - 1);
            if (c == null)
                c = colorAt(x - 1, y);
            if (c == null)
                c = colorAt(x - 1, y - 1);
            if (c != null) {
                int DX = x - eye.getX();
                double DY = y - eye.getY();
                hit = true;
                break;
            }
        }
        if (!hit && slope != Double.POSITIVE_INFINITY) // check back wall
            for (int x = firstX; x >= 0; x -= SQUARE_SIZE) {
                int y = (int) (slope * (x - eye.getX()) + eye.getY());
                if (isOutside(x, y, Color.MAGENTA, this.showRayCastingX))
                    break;
                c = colorAt(x, y);
                z = heightAt(x, y);
                if (c == null)
                    c = colorAt(x, y - 1);
                if (c == null)
                    c = colorAt(x - 1, y);
                if (c == null)
                    c = colorAt(x - 1, y - 1);
                if (c != null) {
                    int DX = x - eye.getX();
                    double DY = y - eye.getY();
                    hit = true;
                    break;
                }
            }
    } else {
        int firstX = ((eye.getX() / SQUARE_SIZE)) * SQUARE_SIZE;
        for (int x = firstX; x >= 0; x -= SQUARE_SIZE) {
            int y = (int) (slope * (x - eye.getX()) + eye.getY());
            if (isOutside(x, y, Color.MAGENTA, this.showRayCastingX))
                break;
            Color c = colorAt(x, y);
            int z = heightAt(x, y);
            if (c == null)
                c = colorAt(x, y - 1);
            if (c == null)
                c = colorAt(x - 1, y);
            if (c == null)
                c = colorAt(x - 1, y - 1);
            if (c != null) {
                int DX = x - eye.getX();
                double DY = y - eye.getY();
                hit = true;
                break;
            }
        }
        if (!hit && slope != Double.POSITIVE_INFINITY) // check back wall
            for (int x = firstX; x < map[0].length * SQUARE_SIZE; x += SQUARE_SIZE) {
                int y = (int) (slope * (x - eye.getX()) + eye.getY());
                if (isOutside(x, y, Color.MAGENTA, this.showRayCastingX))
                    break;
                Color c = colorAt(x, y);
                int z = heightAt(x, y);
                if (c == null)
                    c = colorAt(x, y - 1);
                if (c == null)
                    c = colorAt(x - 1, y);
                if (c == null)
                    c = colorAt(x - 1, y - 1);
                if (c != null) {
                    int DX = x - eye.getX();
                    double DY = y - eye.getY();
                    hit = true;
                    break;
                }
            }
    }

    // If hit, compute projected height and adjust rendering
    if (hit) {
        h = (int) (this.screenDistance / distance * z);
        int hw = (int) (this.screenDistance / distance * WALL_HEIGHT); // WALL_HEIGHT value is 300px at default
        int y0 = (hw + vh) / 2;
        int y1 = (vh - h) / 2;
        graphics.drawLine(xOnScreen, y0, xOnScreen, y1);
    }

Additional Notes:

• Update the castRayInY function in a similar manner.

• To detect back faces of walls, simply add another slope condition:

  } else if (slope > 0 && slope < Double.POSITIVE_INFINITY) {...} // back face

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