This project has been created as part of the 42 curriculum by abelov.

FdF

Description

FdF renders a wireframe model of a landscape from a .fdf height map. Each value in the map represents a point altitude, and neighbouring points are connected with line segments. The default projection is isometric; parallel and cabinet projections are available at runtime.

The project uses MiniLibX for window creation, image buffers, and keyboard/mouse events. Line rasterization is implemented in the project with a Bresenham-style renderer that writes into an MLX image before blitting it to the window.

Instructions

Build the mandatory program:

make

Run it with a map:

./fdf resources/demo_maps/height.fdf

Other useful commands:

make bonus
make test
make clean
make fclean
make re

Current controls:

• ESC or keypad 5: close the window
• Window close button: close the window
• 1: isometric projection
• 2: parallel projection
• 3: cabinet projection
• Space: reset zoom, pan, rotation, and height factor
• Keypad + / -: increase or decrease height exaggeration
• Arrow keys: translate the model
• Q, E, W, S, A, D: rotate the model
• Mouse wheel: zoom toward the mouse pointer
• Middle mouse button drag: pan the model

Rendering reference

This section documents the constants used by the renderer. They are intentionally kept in include/ft_fdf.h so the projection, controls, and fitting behaviour can be tuned without searching through the drawing code.

Window fitting

The window size is estimated from the map dimensions before MiniLibX is initialized. The goal is to open a reasonably sized window for the default view, then let the user adjust it with zoom and pan.

Constant	Value	Used for
FDF_INIT_SCALE	20	Initial xy_scale and z_scale before fitting
FDF_WIN_MAX_WIDTH	1024	Maximum window width
FDF_WIN_MAX_HEIGHT	768	Maximum window height
FDF_WIN_WIDTH_FACTOR	280	Width estimate multiplier
FDF_PERCENT_DIVISOR	10	Shared divisor for percentage-style calculations
FDF_FIT_SCALE_NUMERATOR	10000	Scale numerator used when width is capped
FDF_GRID_SCALE_FACTOR	7	Extra grid margin in the height estimate
FDF_HEIGHT_MARGIN_DIVISOR	20	Margin divisor for fitting calculations

The width estimate starts from the longest map side:

window_width = max(cols, rows) * FDF_WIN_WIDTH_FACTOR * 2 / FDF_PERCENT_DIVISOR

If this is wider than FDF_WIN_MAX_WIDTH, the width is clamped and xy_scale is reduced:

xy_scale = FDF_FIT_SCALE_NUMERATOR / (min(cols, rows) * FDF_GRID_SCALE_FACTOR * 2)

The height estimate combines altitude and grid margin:

grid_margin = (cols + rows) * xy_scale / FDF_HEIGHT_MARGIN_DIVISOR
window_height = max_height * 2 * xy_scale + grid_margin

If the result is taller than FDF_WIN_MAX_HEIGHT, the height is clamped and z_scale is reduced when the map has a positive maximum height.

From map point to world point

The renderer first recenters each map point around the middle of the map. This keeps rotation natural because the model spins around its own centre instead of around the top-left corner.

Symbol	Meaning
col	Column index from the map
row	Row index used by the renderer
height	Parsed altitude at (col, row)
X, Y, Z	Centered world-space coordinates
screen_scale	Final multiplier used by projection formulas

X = col - (cols - 1) / 2
Y = row - (rows - 1) / 2
Z = height * z_scale / xy_scale * z_factor
screen_scale = xy_scale * zoom

The first row in the input file is traversed with row = rows - 1; the last row is traversed with row = 0. This preserves the intended back-to-front drawing order for the default view.

Rotation

Rotations are applied before projection, in this order: X, then Y, then Z. Angles are stored in radians, and each keypress changes one angle by FDF_ROT_STEP.

Constant	Value	Used for
FDF_ROT_STEP	0.035	Rotation amount per keypress, in radians

Plane	Formula
X	Y' = Y * cos(angle) - Z * sin(angle), Z' = Y * sin(angle) + Z * cos(angle)
Y	X' = X * cos(angle) + Z * sin(angle), Z' = -X * sin(angle) + Z * cos(angle)
Z	X' = X * cos(angle) - Y * sin(angle), Y' = X * sin(angle) + Y * cos(angle)

Projections

Projection constants are divisors. Larger divisors make that axis visually shorter. Parallel and cabinet projection use a depth divisor to foreshorten the receding axis.

Constant	Value	Used for
FDF_PROJ_ISO	1	Isometric projection mode
FDF_PROJ_PARALLEL	2	Parallel projection mode
FDF_PROJ_CABINET	3	Cabinet projection mode
FDF_ISO_X_DIVISOR	10	Isometric horizontal scale
FDF_ISO_Y_DIVISOR	20	Isometric ground-plane vertical scale
FDF_PARALLEL_DIVISOR	8	Parallel projection scale
FDF_PARALLEL_DEPTH_DIVISOR	2	Parallel receding-axis foreshortening
FDF_CABINET_X_DIVISOR	8	Cabinet projection scale
FDF_CABINET_DEPTH_DIVISOR	4	Cabinet receding-axis foreshortening

W and H are the window width and height. pan_x and pan_y are added at the end so panning works the same way in every projection.

Isometric

screen_x = (X - Y) * screen_scale / FDF_ISO_X_DIVISOR
           + W / 2 + pan_x

screen_y = H / 2
           - (X + Y) * screen_scale / FDF_ISO_Y_DIVISOR
           - Z * screen_scale / FDF_ISO_X_DIVISOR
           + pan_y

Parallel

screen_x = (X + Y / FDF_PARALLEL_DEPTH_DIVISOR)
           * screen_scale / FDF_PARALLEL_DIVISOR
           + W / 2 + pan_x

screen_y = (-Y / FDF_PARALLEL_DEPTH_DIVISOR - Z)
           * screen_scale / FDF_PARALLEL_DIVISOR
           + H / 2 + pan_y

Cabinet

screen_x = (X + Y / FDF_CABINET_DEPTH_DIVISOR)
           * screen_scale / FDF_CABINET_X_DIVISOR
           + W / 2 + pan_x

screen_y = (-Y / FDF_CABINET_DEPTH_DIVISOR - Z)
           * screen_scale / FDF_CABINET_X_DIVISOR
           + H / 2 + pan_y

View controls

The view state is stored separately from parsed map data. Projection switches, pan, rotation, zoom, and height exaggeration only change t_view; the map itself is not modified.

Constant	Value	Used for
FDF_PAN_STEP	25	Keyboard pan amount, in pixels
FDF_Z_FACTOR_MIN	0.1	Minimum height exaggeration
FDF_Z_FACTOR_MAX	10.0	Maximum height exaggeration
FDF_Z_FACTOR_STEP	0.1	Height exaggeration change per keypad press
FDF_ZOOM_MIN	0.1	Minimum zoom
FDF_ZOOM_MAX	70	Maximum zoom
FDF_SCROLL_UP	4	X11 mouse wheel-up button
FDF_SCROLL_DOWN	5	X11 mouse wheel-down button
FDF_MOUSE_MIDDLE	2	X11 middle mouse button

Mouse wheel zoom changes the current zoom by ten percent:

next_zoom = zoom +/- zoom / FDF_PERCENT_DIVISOR

The pan is adjusted during zoom so the point under the cursor stays under the cursor. If the mouse has not been active yet, the window centre is used instead. Pressing Space resets zoom, pan, rotation, height factor, and mouse state, but keeps the currently selected projection.

Input	Effect
1, 2, 3	Select isometric, parallel, or cabinet projection
Arrow keys	Pan by FDF_PAN_STEP
W / S	Rotate around X by +/- FDF_ROT_STEP
A / D	Rotate around Y by +/- FDF_ROT_STEP
Q / E	Rotate around Z by +/- FDF_ROT_STEP
Keypad + / -	Change height exaggeration by +/- FDF_Z_FACTOR_STEP
Mouse wheel	Zoom in or out
Middle mouse drag	Pan by pointer movement
Space	Reset the view state, preserving projection
ESC, keypad 5, window close	Exit cleanly

Colour and image output

Constant	Value	Used for
WHITE_COLOR	0xffffff	Default point colour
FDF_RGB_RED_SHIFT	16	Red channel extraction
FDF_RGB_GREEN_SHIFT	8	Green channel extraction
FDF_RGB_MODULO	256	RGB channel isolation

Map entries can be either height or height,color. If no colour is provided, WHITE_COLOR is used. Lines interpolate red, green, and blue channels separately while Bresenham walks from one endpoint to the other.

The renderer draws into an MLX image buffer and then blits that image to the window. Pixel writes are clipped to the valid image range 0..width-1 and 0..height-1.

Resources

• 42 FdF subject v5.0
• MiniLibX documentation and sources
• X11 documentation for expose events and image formats
• Bresenham line algorithm references for integer line rasterization

AI was used as a review and planning aid: drafting staged refactor plans, and checking implementation risks. All code changes are reviewed and owned by the project author.