raymarcher.h/marcher.c

#include <math.h>
#include <stdlib.h>
#include <stdio.h>
#include "images/src/images.h"
#include "src/scene.h"
#include "src/camera.h"
#include "src/point.h"

#define SCENE_MOD 2


/*

    Infinite circle scene object

    This circle repeats every SCENE_MOD units in all directions

    It has some basic shading, calculation the hit angle and making shallower impacts darker

*/

double circle_dist(struct point x, struct scene_object *self) {
    double r = self->args[0];
    return pt_dist(pt_mod(x, SCENE_MOD), self->location) - r;
}

Color circle_color(struct point hit, struct point direction, struct scene_object *self) {
    struct point obj_direction = self->location;

    obj_direction = pt_sub(obj_direction, pt_mod(hit, SCENE_MOD));

    double angle = pt_angle(direction, obj_direction) / M_PI * 180;
    Color color = self->color;

    if (angle > 90) angle = 180 - angle ; // clamp angle to 0-90
    color = color_mix(color, color_new(0,0,0), 1 - (angle / (double) 120));

    return color;
}
// constructs the scene object
struct scene_object circle_new(struct point loc, double radius) {
    double * args = malloc(sizeof (double) * 2);
    args[0] = radius;
    return (struct scene_object) {
            .location = loc,
            .args = args,
            .distance = circle_dist,
            .get_color = circle_color,
            .color = color_new(255, 255, 255),
    };
}


/*

    Mandelbulb scene object

    Currently cannot be set at a specific location, always resides at origin (0,0,0)

    Color function is just a flat shader, detail is displayed with ambient occlusion

*/
double mandelbulb_dist(struct point pt, struct scene_object *self) {
    int iters = self->args[0];
    double power = self->args[1];

    struct point z = pt;
	float dr = 1.0;
	float r = 0.0;
	for (int i = 0; i < iters ; i++) {
		r = pt_length(z);

		if (r>2) {
            break;
        }
		
		// convert to polar coordinates
		float theta = acos(z.z/r);
		float phi = atan2(z.y,z.x);
		dr =  pow(r, power-1.0)*power*dr + 1.0;
		
		// scale and rotate the point
		float zr = pow(r, power);
		theta = theta*power;
		phi = phi*power;
		
		// convert back to cartesian coordinates, add zr and the old pt
		z = (struct point) {
            .x = sin(theta)*cos(phi) * zr + pt.x,
            .y = sin(phi)*sin(theta) * zr + pt.y,
            .z = cos(theta) * zr + pt.z
        };
	}
	
    return 0.5*log(r)*r/dr;
}

Color mandelbulb_color(struct point hit, struct point direction, struct scene_object *self) {
    return self->color;
}
// constructs the scene object
struct scene_object mandelbulb_new(struct point location, int iters, double power) {
    double * args = malloc(sizeof(double) * 3);
    args[0] = iters;
    args[1] = power;
    args[2] = -1;

    return (struct scene_object) {
        .location=  location,
        .args= args,
        .distance=  mandelbulb_dist,
        .get_color=  mandelbulb_color,
        .color=  color_new(255,255,255),
    };
}

int main(int argc, char* argv[]) {
    float dpi = 200;

    int threads = 32;
    int size = dpi * 27.56f;       // 400dpi by 70cm size
    float pow = 3;
    float cam_position = 1.35;
    int steps = 1000;
    int iters = 500;
    float threshold = 0.001;
    char path[80];


    // get params from cli
    if (argc < 5) {
        return 1;
    }
    pow = atof(argv[1]);
    steps = atoi(argv[2]);
    iters = atoi(argv[3]);
    threshold = atof(argv[4]);

    sprintf(path, "tries/pow%.2f-%ist-%iit-%.5fth-%.0fdpi.bmp", pow, steps, iters, threshold, dpi);

    printf("Rendering to %s\n", path);

    struct camera cam;
    cam.fov = 90;

    camera_set_looking_at(&cam, (struct point){.x=cam_position, .y= 0, .z = cam_position}, PT_ZERO);

    // create basic scene with up to 10 objects
    struct scene scene = scene_new(size, size, 1);
    scene.perf_opts.max_steps = steps;
    scene.perf_opts.threshold = threshold;
    scene.perf_opts.speed_cutoff = 10;
    scene.background = color_new(0,0,0);

    //scene_add_obj(&scene, circle_new(pt_new(SCENE_MOD / 2.0, SCENE_MOD/ 2.0, SCENE_MOD / 2.0), .2));

    scene_add_obj(&scene, mandelbulb_new(PT_ZERO, iters, pow));
    
    Image *img = render_scene(&scene, &cam, threads);

    image_save_bmp(*img, path);

    image_destroy_shared(*img);
    scene_destroy(scene);

    return 0;  
}