donut.cpp

donut.cpp

// yes.

#include <algorithm>


#define MAX_SIZE 1760
#define CHARS_MAP ".,-~:;=!*#$@"


float step_x = 0;
float step_y = 0;

float transforms[ MAX_SIZE ];
char  chars[ MAX_SIZE ];


void draw_donut( ) {
	memset( chars, 32, MAX_SIZE );
	memset( transforms, 0, MAX_SIZE * 4 );

	float step_x_sin = static_cast< float >( sin( step_x ) );
	float step_x_cos = static_cast< float >( cos( step_x ) );

	float step_y_sin = static_cast< float >( sin( step_y ) );
	float step_y_cos = static_cast< float >( cos( step_y ) );

	for ( float pos_x = 0.f; 6.28f > pos_x; pos_x += 0.07f ) {
		for ( float pos_y = 0.f; 6.28f > pos_y; pos_y += 0.02f ) {
			float x_sin = static_cast< float >( sin( pos_x ) );
			float x_cos = static_cast< float >( cos( pos_x ) );
			float x_cos_mult = x_cos + 2.f;

			float y_sin = static_cast< float >( sin( pos_y ) );
			float y_cos = static_cast< float >( cos( pos_y ) );

			float new_transform_value = 1.f / ( y_sin * x_cos_mult * step_x_sin + x_sin * step_x_cos + 5.f );
			float multiplier = y_sin * x_cos_mult * step_x_cos - x_sin * step_x_sin;

			int x = static_cast< int >( 40 + 30 * new_transform_value * ( y_cos * x_cos_mult * step_y_cos - multiplier * step_y_sin ) );
			int y = static_cast< int >( 12 + 15 * new_transform_value * ( y_cos * x_cos_mult * step_y_sin + multiplier * step_y_cos ) );

			int index = x + 80 * y;

			if ( !( 22 > y && y > 0 && x > 0 && 80 > x && new_transform_value > transforms[ index ] ) ) continue;

			transforms[ index ] = new_transform_value;

			float x_sinuses = x_sin * step_x_sin;
			float left = x_sinuses - y_sin * x_cos * step_x_cos;
			left *= step_y_cos;

			float rightpt1 = y_sin * x_cos * step_x_sin;
			float rightpt2 = x_sin * step_x_cos;
			float rightpt3 = y_cos * x_cos * step_y_sin;

			float result = left - rightpt1 - rightpt2 - rightpt3;

			chars[ index ] = CHARS_MAP[ std::max( static_cast< int >( 8 * result ), 0 ) ];
		}
	}

	printf( "\x1b[H" );
	for ( int k = 0; ( MAX_SIZE + 1 ) > k; k++ )
		putchar( k % 80 ? chars[ k ] : 10 );

	step_x += 0.04f;
	step_y += 0.02f;
}

int main( ) {
	printf( "\x1b[2J" );
	for ( ;; )
		draw_donut( );
}