Break down this C++ code and explain what it does:

```
#include "Graphics.h"

#include "Texture.h"
#include "Camera.h"

#define SET_COLOR() SDL_SetRenderDrawColor(handle, color.r, color.g, color.b, color.a)

#define CAM Camera::getActive()
#define CAM_POS CAM->position

void Graphics::drawLine(const Vec2 &from, const Vec2 &to, const Color &color) {
    SET_COLOR();
    Vec2 f = from - CAM_POS;
    SDL_RenderDrawLineF(handle, f.x, f.y, to.x, to.y);
}

void Graphics::drawLine(const Vec2 &origin, const Vec2 &direction,
                        const Vec2 &length, const Color &color) {
    drawLine(origin, origin + direction * length, color);
}

void Graphics::drawPoint(const Vec2 &position, const Color &color) {
    SET_COLOR();
    Vec2 p = position - CAM_POS;
    SDL_RenderDrawPointF(handle, position.x, position.y);
}

void Graphics::drawRect(const Rect &rect, const Color &color) {
    SET_COLOR();
    SDL_FRect r = rect;
    r.x -= CAM_POS.x;
    r.y -= CAM_POS.y;
    SDL_RenderDrawRectF(handle, &r);
}

void Graphics::fillRect(const Rect &rect, const Color &color) {
    SET_COLOR();
    SDL_FRect r = rect;
    r.x -= CAM_POS.x;
    r.y -= CAM_POS.y;
    SDL_RenderFillRectF(handle, &r);
}
```
user
This is a code written in C++, and it appears to be part of a graphics library. The code defines a number of functions that are used to draw various shapes on the screen, such as lines, points, and rectangles.

The #include statements at the top of the code import the necessary headers for the classes used in the code. The Graphics class defined in this code is dependent on the Texture and Camera classes, which are included in the code.

The #define statements define macros that can be used later in the code. The SET_COLOR macro sets the render color for the graphics handle using the SDL_SetRenderDrawColor function. The CAM and CAM_POS macros retrieve the active camera and its position, respectively.

The first function, drawLine, draws a line between two points, from and to, and it takes a color argument. The function subtracts the camera position from each point so that the line is drawn relative to the camera's position. The SDL_RenderDrawLineF function is used to draw the line.

The second function, drawLine, draws a line with an origin, a direction, and a length, and it takes a color argument. The function calls the first drawLine function, passing the origin and the origin plus the direction multiplied by the length as the two points.

The third function, drawPoint, draws a point at a specified position, and it takes a color argument. The function subtracts the camera position from the position, then uses the SDL_RenderDrawPointF function to draw the point.

The fourth function, drawRect, draws an outline of a rectangle, and it takes a color argument. The function subtracts the camera position from the rectangle's position and uses the SDL_RenderDrawRectF function to draw the rectangle.

The fifth function, fillRect, fills a rectangle with a specified color, and it takes a color argument. The function subtracts the camera position from the rectangle's position and uses the SDL_RenderFillRectF function to fill the rectangle.
assistant