MechanicsSketches Skill
You can generate engineering mechanics sketches programmatically using the MechanicsSketches Python library.
Setup
Install the library via pip:
pip install git+https://github.com/MatthiasHBusch/MechanicsSketches.git
Or install dependencies manually and add to PYTHONPATH:
pip install matplotlib PyQt5
export PYTHONPATH="/path/to/parent/of/MechanicsSketches:$PYTHONPATH"
Quick Start — Writing a Script
Create a Python script that builds a sketch and renders it:
from MechanicsSketches import *
import os
sketch = create_sketch("My Sketch")
S = 30.0 # Scale factor (recommended: 20-40)
# Add components
add_beam(sketch, ax=0, ay=0, bx=10*S, by=0, scale_factor=S)
add_pinned_support(sketch, cx=0, cy=0, angle_deg=0, scale_factor=S)
add_roller_support(sketch, cx=10*S, cy=0, angle_deg=0, scale_factor=S)
add_force(sketch, cx=5*S, cy=0, angle_deg=0, scale_factor=S, annotation=r"$F$")
# Render
script_dir = os.path.dirname(os.path.abspath(__file__))
render(sketch, filename=os.path.join(script_dir, "output.pdf"), dpi=300)
Then run: python my_sketch.py
Quick Start — Using the Helper Script
Alternatively, use the bundled helper to render from JSON:
python scripts/generate_sketch.py input.json output.pdf
Key Concepts
Scale Factor (S)
All positions and sizes should be multiples of S (typically 30.0). This keeps proportions consistent across components.
Angle Convention
angle_deg=0 → default orientation (upward for supports/forces, horizontal for dimensions)- Angles rotate counterclockwise in degrees
Available Components
| Function |
Description |
Key Parameters |
add_beam(sketch, ax, ay, bx, by, scale_factor) |
Rectangular beam A→B |
Endpoints, scale |
add_truss(sketch, ax, ay, bx, by, scale_factor) |
Line member A→B |
Endpoints, scale |
add_pinned_support(sketch, cx, cy, angle_deg, scale_factor) |
Fixed-position support (triangle) |
Center, angle, scale |
add_roller_support(sketch, cx, cy, angle_deg, scale_factor) |
Sliding support |
Center, angle, scale |
add_fixed_support(sketch, cx, cy, angle_deg, scale_factor) |
Clamped wall support |
Center, angle, scale |
add_hinge(sketch, cx, cy, scale_factor) |
Joint circle |
Center, scale |
add_force(sketch, cx, cy, angle_deg, scale_factor, annotation, ...) |
Force arrow |
Center, angle, scale, label |
add_moment(sketch, cx, cy, angle_deg, scale_factor, annotation, ...) |
Curved moment arrow |
Center, angle, scale, label |
add_dimension_arrow(sketch, cx, cy, length, angle_deg, scale_factor, annotation, ...) |
Double-headed dimension |
Center, length, angle, scale, label |
add_dimension_thickness(sketch, cx, cy, thickness, angle_deg, scale_factor, annotation, ...) |
Inward dimension arrows |
Center, thickness, angle, scale, label |
add_coordinate_system(sketch, cx, cy, angle_deg, scale_factor, ax1, ax2, ax3, ...) |
x-y-z axes |
Center, angle, scale, axis labels |
add_text(sketch, x, y, text, fontsize, name, rotation) |
Text annotation |
Position, text, font size |
Annotation Parameters
Force, moment, and dimension functions accept:
annotation — LaTeX string (e.g., r"$F$", r"$M_A$")fontsize_scale — relative font size (default 1.0)offsetx, offsety — label position offsetrotate_annotation — rotate label with component (default False)
Primitives
For custom shapes, use:
make_line(x0, y0, x1, y1, linewidth, layer, edgecolor)make_circle(x, y, r, linewidth, layer, facecolor, edgecolor)make_polygon(points, linewidth, layer, facecolor, edgecolor)make_arc(x, y, width, height, theta1, theta2, angle, linewidth, layer)make_text(x, y, text, fontsize, layer, color, ha, va, rotation)make_rectangle(x0, y0, x1, y1, ...)
Add to sketch via add_to_sketch(sketch, primitive).
Transformations
translate(obj, dx, dy) — move by offsetrotate(obj, cx, cy, angle_deg) — rotate around pointscale(obj, cx, cy, factor) — scale from center
All return new objects (non-destructive). Can be chained.
Rendering
render(sketch, filename="output.pdf", dpi=300) # Qt renderer (default, recommended)
mpl_render(sketch, filename="output.pdf") # Matplotlib fallback (deprecated, text scaling issues)
Supported formats: .pdf, .png, .jpg, .svg
Tips for the Agent
- Always define
S = 30.0 as the scale factor
- Place beams first, then supports at endpoints, then loads
- Use LaTeX for annotations:
r"$F$", r"$M_0$", r"$\ell$"
- For detailed API signatures, see
references/api_reference.md
- The
render() function requires a filename — it does not display interactively
- Do not use
mpl_render() — it is deprecated due to text scaling issues. Always use render().
External Endpoints
This skill makes no network requests. All processing is done locally.
Security & Privacy
- No data leaves your machine. The skill only reads local JSON files and writes local image/PDF output.
- No API keys or credentials are required.
- No telemetry or analytics.
- The helper script (
scripts/generate_sketch.py) only reads the input file specified by the user and writes to the specified output path.
Trust Statement
This skill is developed and maintained by MatthiasHBusch. The source code is fully open under the MIT license. All functionality runs locally with no external dependencies beyond standard Python packages (matplotlib, PyQt5).
1---2name: mechanics-sketches3description: Generate technical engineering mechanics sketches (beams, supports, forces, moments, dimensions, coordinate systems) as PDF/PNG/SVG using the MechanicsSketches Python library. Use this skill when asked to create free-body diagrams, structural sketches, or mechanical engineering figures.4---56# MechanicsSketches Skill78You can generate engineering mechanics sketches programmatically using the **MechanicsSketches** Python library.910## Setup1112Install the library via pip:1314```bash15pip install git+https://github.com/MatthiasHBusch/MechanicsSketches.git16```1718Or install dependencies manually and add to `PYTHONPATH`:1920```bash21pip install matplotlib PyQt522export PYTHONPATH="/path/to/parent/of/MechanicsSketches:$PYTHONPATH"23```2425## Quick Start — Writing a Script2627Create a Python script that builds a sketch and renders it:2829```python30from MechanicsSketches import *31import os3233sketch = create_sketch("My Sketch")34S = 30.0 # Scale factor (recommended: 20-40)3536# Add components37add_beam(sketch, ax=0, ay=0, bx=10*S, by=0, scale_factor=S)38add_pinned_support(sketch, cx=0, cy=0, angle_deg=0, scale_factor=S)39add_roller_support(sketch, cx=10*S, cy=0, angle_deg=0, scale_factor=S)40add_force(sketch, cx=5*S, cy=0, angle_deg=0, scale_factor=S, annotation=r"$F$")4142# Render43script_dir = os.path.dirname(os.path.abspath(__file__))44render(sketch, filename=os.path.join(script_dir, "output.pdf"), dpi=300)45```4647Then run: `python my_sketch.py`4849## Quick Start — Using the Helper Script5051Alternatively, use the bundled helper to render from JSON:5253```bash54python scripts/generate_sketch.py input.json output.pdf55```5657## Key Concepts5859### Scale Factor (`S`)6061All positions and sizes should be multiples of `S` (typically 30.0). This keeps proportions consistent across components.6263### Angle Convention6465- `angle_deg=0` → default orientation (upward for supports/forces, horizontal for dimensions)66- Angles rotate counterclockwise in degrees6768### Available Components6970| Function | Description | Key Parameters |71|----------|-------------|----------------|72| `add_beam(sketch, ax, ay, bx, by, scale_factor)` | Rectangular beam A→B | Endpoints, scale |73| `add_truss(sketch, ax, ay, bx, by, scale_factor)` | Line member A→B | Endpoints, scale |74| `add_pinned_support(sketch, cx, cy, angle_deg, scale_factor)` | Fixed-position support (triangle) | Center, angle, scale |75| `add_roller_support(sketch, cx, cy, angle_deg, scale_factor)` | Sliding support | Center, angle, scale |76| `add_fixed_support(sketch, cx, cy, angle_deg, scale_factor)` | Clamped wall support | Center, angle, scale |77| `add_hinge(sketch, cx, cy, scale_factor)` | Joint circle | Center, scale |78| `add_force(sketch, cx, cy, angle_deg, scale_factor, annotation, ...)` | Force arrow | Center, angle, scale, label |79| `add_moment(sketch, cx, cy, angle_deg, scale_factor, annotation, ...)` | Curved moment arrow | Center, angle, scale, label |80| `add_dimension_arrow(sketch, cx, cy, length, angle_deg, scale_factor, annotation, ...)` | Double-headed dimension | Center, length, angle, scale, label |81| `add_dimension_thickness(sketch, cx, cy, thickness, angle_deg, scale_factor, annotation, ...)` | Inward dimension arrows | Center, thickness, angle, scale, label |82| `add_coordinate_system(sketch, cx, cy, angle_deg, scale_factor, ax1, ax2, ax3, ...)` | x-y-z axes | Center, angle, scale, axis labels |83| `add_text(sketch, x, y, text, fontsize, name, rotation)` | Text annotation | Position, text, font size |8485### Annotation Parameters8687Force, moment, and dimension functions accept:88- `annotation` — LaTeX string (e.g., `r"$F$"`, `r"$M_A$"`)89- `fontsize_scale` — relative font size (default 1.0)90- `offsetx`, `offsety` — label position offset91- `rotate_annotation` — rotate label with component (default False)9293### Primitives9495For custom shapes, use:96- `make_line(x0, y0, x1, y1, linewidth, layer, edgecolor)`97- `make_circle(x, y, r, linewidth, layer, facecolor, edgecolor)`98- `make_polygon(points, linewidth, layer, facecolor, edgecolor)`99- `make_arc(x, y, width, height, theta1, theta2, angle, linewidth, layer)`100- `make_text(x, y, text, fontsize, layer, color, ha, va, rotation)`101- `make_rectangle(x0, y0, x1, y1, ...)`102103Add to sketch via `add_to_sketch(sketch, primitive)`.104105### Transformations106107- `translate(obj, dx, dy)` — move by offset108- `rotate(obj, cx, cy, angle_deg)` — rotate around point109- `scale(obj, cx, cy, factor)` — scale from center110111All return new objects (non-destructive). Can be chained.112113### Rendering114115```python116render(sketch, filename="output.pdf", dpi=300) # Qt renderer (default, recommended)117mpl_render(sketch, filename="output.pdf") # Matplotlib fallback (deprecated, text scaling issues)118```119120Supported formats: `.pdf`, `.png`, `.jpg`, `.svg`121122## Tips for the Agent1231241. Always define `S = 30.0` as the scale factor1252. Place beams first, then supports at endpoints, then loads1263. Use LaTeX for annotations: `r"$F$"`, `r"$M_0$"`, `r"$\ell$"`1274. For detailed API signatures, see `references/api_reference.md`1285. The `render()` function requires a filename — it does not display interactively1296. Do **not** use `mpl_render()` — it is deprecated due to text scaling issues. Always use `render()`.130131## External Endpoints132133This skill makes **no network requests**. All processing is done locally.134135## Security & Privacy136137- **No data leaves your machine.** The skill only reads local JSON files and writes local image/PDF output.138- No API keys or credentials are required.139- No telemetry or analytics.140- The helper script (`scripts/generate_sketch.py`) only reads the input file specified by the user and writes to the specified output path.141142## Trust Statement143144This skill is developed and maintained by [MatthiasHBusch](https://github.com/MatthiasHBusch). The source code is fully open under the MIT license. All functionality runs locally with no external dependencies beyond standard Python packages (matplotlib, PyQt5).
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