Being the Artist

Valora's runtime interface.

Valora provides a trait, Artist, which you must implement in order to draw. The trait looks like this:

/// A trait for types which paint canvases.
pub trait Artist: Sized {
    /// Constructs the artist.
    ///
    /// This would be a place to compile any GLSL or construct any expensive
    /// resources needed across the whole composition.
    fn setup(gpu: Gpu, world: World, rng: &mut StdRng) -> Result<Self>;

    /// Paints a single frame.
    fn paint(&mut self, ctx: Context, canvas: &mut Canvas);
}

To run a drawing, call

run::<YourArtistType>(Options::from_args())

Calling Options::from_args() will provide valora's command line interface, which is shown below. This is all you have to do! The rendering, saving to file, resolutions, seed, etc, can all be configured by the command line interface without any changes to code.

There is also a convenience implementation of Artist for functions that return painting functions, such as we used in the introduction:

run_fn(Options::from_args(), |gpu, world, rng| {
    Ok(move |ctx: Context, canvas: &mut Canvas| {
        // Paint frames here
    })
})

The full command line interface:

Command line options for a painting run.

Construct with `Options::from_args()` to run the CLI.

USAGE:
    simple [FLAGS] [OPTIONS]

FLAGS:
    -b, --brainstorm    
            In brainstorm mode:
            
            * When rendering a limited number of frames to screen, the preview
              will not close.
            
            * When rendering to file, every frame will be rendered with a
              different seed.
        --help          
            Prints help information

    -V, --version       
            Prints version information


OPTIONS:
    -d, --delay <delay>                    
            The number of frames to delay saving to file. For example, if
            delay=100, 100 frames will be rendered silently and then the 101st
            and those after it will be saved to file. [default: 0]
    -r, --frames_per_second <framerate>    
            The number of frames (to try) to render per second. [default: 24]

    -f, --frames <frames>                  
            The total number of frames in this painting.

    -h, --height <height>                  
            The height in coordinate space of the painting.
            
            Coordinate space may differ from output space. If height is 500 but
            scale is 10, the painting will have a coordinate space height of 500,
            but the final output will have a height of 5000 pixels. [default: 650]
    -o, --output <output>                  
            Prefix of output path. Output is <prefix>/<seed>/<frame_number>.png

    -s, --scale <scale>                    
            The scale of the output.
            
            The final output space is (width*scale)x(height*scale). This value is
            useful for painting and doing work at one quickly rendering
            resolution, and later exporting at a much higher resolution while
            preserving the composition exactly.
            
            This value may be needed when writing shaders or using other raster
            graphics, to adjust them for the real output size. Vector painting
            such as with paths should not need to consider this. [default: 1.0]
    -e, --seed <seed>                      
            The RNG seed for this painting. [default: 0]

    -w, --width <width>                    
            The width in coordinate space of the painting.
            
            Coordinate space may differ from output space. If width is 500 but
            scale is 10, the painting will have a coordinate space width of 500,
            but the final output will have a width of 5000 pixels. [default: 512]