// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
/*
Krakatoa SR API example file.

EXAMPLE 18
-Uses channel operation "Copy" to copy "Position" channel into "Emission" channel.
-Uses channel operation "Scale" to scale down the "Color" channel so a nice gradient appears around the origin.
*/

#include <iostream>
#include <krakatoasr_renderer.hpp>

int main( void ) {
    try {
        // This example creates a self illuminating fractal it then copies the position channels of each particle into
        // that particles emission channel and scales the color channel

        krakatoasr::krakatoa_renderer renderer;
        // here we are creating a transform that we will be applying to the camera to move it 10 units in the z
        // direction
        krakatoasr::animated_transform cameraTransform =
            krakatoasr::animated_transform( 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 10, 1 );
        // we now apply the transform to the camera
        renderer.set_camera_tm( cameraTransform );
        // Here we are setting the density of the particles in the final render.
        // after this change the end density will be 9*10^-1
        renderer.set_density_per_particle( 5 );
        // change the exponent on the final render particle density
        // after this change the end density will be 9*10^-3
        renderer.set_density_exponent( -6 );
        // we are now creating the parameters that will be used for the fractals
        krakatoasr::fractal_parameters fractalParams;
        // we are setting these parameters from a random generator using 5 affine transformations and 4 different colors
        // being used
        fractalParams.set_from_random( 5, 3, 46 );
        // we now create the particle stream from the fractal parameters from last step with a total particle count of
        // 5,000,000
        krakatoasr::particle_stream particleStream =
            krakatoasr::particle_stream::create_from_fractals( 5000000, fractalParams );
        // We now copy the position channel to the emission channel
        // Note that the destination channel is before the source channel
        krakatoasr::channelop_copy( particleStream, "Emission", "Position" );
        // we then scale the Color channel of the particle stream by a factor of 400
        krakatoasr::channelop_scale( particleStream, "Color", 400 );
        // we now add the particle stream to the renderer
        renderer.add_particle_stream( particleStream );
        // since we are using emission instead of lights we must tell the renderer that.
        renderer.use_emission( true );
        // for the emission we want to lower the strength so that all of the pixels are do not have there color washed
        // out in this example I am using 1*10^-2
        renderer.set_emission_strength( 7.0 );
        renderer.set_emission_strength_exponent( -6 );
        // we now create a file saver to let krakatoa know where we want our results to go
        krakatoasr::file_saver fileSaver = krakatoasr::file_saver( "example20.exr" );
        // add the file saver to the renderer
        renderer.set_render_save_callback( &fileSaver );
        // and finally start the render
        renderer.render();
    } catch( std::exception& e ) {
        std::cerr << e.what() << std::endl;
        return 1;
    }
    return 0;
}