# E0_GraphCalculator

Interactive 2D equation grapher built with the Ixtli UI/graphics framework.

This example lets you type mathematical expressions and render them in real time,
with support for multiple coordinate interpretations (cartesian, polar, inverse forms),
zoom, pan, and dynamic grid labeling.

## Features

- Real-time expression parsing and plotting while typing.
- Multiple equations in one session (press Enter to add a new equation slot).
- Per-equation random colors (press Shift to recolor the most recent curve).
- Mouse-based navigation:
	- Drag to pan.
	- Scroll up/down to zoom.
- Automatic grid generation with adaptive spacing and numeric labels.
- Built-in expression engine with:
	- Constants: `pi`, `e`.
	- Operators: `+`, `-`, `*`, `/`, `^`, unary minus.
	- Functions: `sin`, `cos`, `tan`, `asin`, `acos`, `atan`, `sinc`, `exp`, `ln`,
		`log`, `log2`, `sqrt`, `floor`, `ceil`, `sign`, `min`, `max`, `avg`.

## Expression Modes

The grapher infers the plotting mode from the variable used in the expression:

- `x` -> Cartesian mode (`y = f(x)`).
- `t` -> Polar mode (`r = f(t)`).
- `y` -> Inverse Cartesian mode (`x = f(y)`).
- `r` -> Inverse Polar mode (`t = f(r)`).

If the expression does not validate for one of those variable sets, it is treated as invalid and not drawn.

## Dependencies

- C++11 compiler (g++ or compatible).
- Ixtli (libixtli)
    - OpenGL.
    - freeglut.
    - libuuid.
    - freetype2 (If ixtli was builded with it).

## Build
### Set Ixtli environment
```bash
export IXTLI_TOP=<Ixtli install path>
```
or
```bash
export IXTLI_CPP_FLAGS=-I<Ixtli include path>
export IXTLI_LD_FLAGS=-L<Ixtli lib path> -lixtli -Wl,-rpath=<Ixtli lib path>
```

### Make

```bash
make -j"$(nproc)"
```

## Run

After building this example directly, the binary is generated at:

```text
./GraphCalculator
```

## Controls

- Type expression in the input box to update current curve.
- Enter: commit current valid expression and start a new empty slot.
- Shift: change the latest curve color.
- Mouse drag: pan.
- Mouse wheel up/down: zoom in/out.