tinysoftraymarc-hackathon/camera.c

#include "main.h"
#include "types.h"
#include "math.h"
#include "vect.h"
#include "distfuncs.h"
#include "camera.h"

#define DRAW_DIST 2550.0
#define MAX_ITERATIONS 255
#define EPSILON 0.1
#define NORMAL_EPSILON 0.0001

double dabs(double yeet) {
        if (yeet > 0) {
                return yeet;
        } else {
                return -yeet;
        }
}

double dsign(double yeet) {
        if (yeet < 0) {
                return -1;
        } else {
                return 1;
        }
}

double manidist(struct vec *v) 
{
        return v->elements[3];
        //double yeet = (SDL_GetTicks() / 10);
        double yeet = 100;
        v->elements[3] -= yeet;
        double out = magnitude_vec(v) - yeet;
        v->elements[3] += yeet;
        return out;
}

struct solid manifold = (struct solid) {
        .dist = manidist,
};

struct colour 
solid_col(struct object *s, struct ray *r) {
        subtract_vec_ip(r->pos, &(s->sol.pos));
        struct colour out = s->col(r, s);
        add_vec_ip(r->pos, &(s->sol.pos));
        return out;
}

double solid_dist(struct solid *s, struct vec *v) {
        subtract_vec_ip(v, &(s->pos));
        double out = s->dist(v);
        add_vec_ip(v, &s->pos);
        return out;
}

/* return a malloced vector, normal to sol at r */ 
struct vec * 
estimateNormal(struct vec *r, struct solid *sol) 
{
        struct vec *out = new_vec(r->dimension);
        struct vec *tmp = new_vec(r->dimension);
        for (int i = 0; i < out->dimension; i++) {
                tmp->elements[i] = NORMAL_EPSILON;
                double s1 = solid_dist(sol, tmp);
                tmp->elements[i] = -NORMAL_EPSILON;
                double s2 = solid_dist(sol, tmp);
                
                out->elements[i] = s1 - s2;
                tmp->elements[i] = 0;
        }
        free_vec(tmp);
        return normalise_vec_ip(out);
}

struct vec *
reyeet(struct vec *v, struct vec *k) {
        struct vec *vs [2];
        // struct vec *tmp = new_vec_of(v->dimension, 1);
        vs[0] = k;
        vs[1] = v;
        // for (int i = 1; i < v->dimension; i++) vs[i] = k;
        struct vec *out = perpendicular_vec(2, vs);
        // free_vec(tmp);
        return out;
}

void
rotateaxis(struct vec *v, struct vec *k, double a)
{
        double cosa = cos(a);        

        struct vec *p = add_scaled_vec_ip(
                add_scaled_vec_ip(scalar_multiply_vec_ip(reyeet(v, k), sin(a)), v, cosa),
                k, dot_product_vec(k, v)*(1 - cosa));

        free(v->elements);
        v->elements = p->elements;
        free(p);
}

int vectorisnan(struct vec *v) 
{
        for (int i = 0; i < v->dimension; i++) {
                if (v->elements[i] != v->elements[i]) 
                        return 1;
        }
        return 0;
}

void
manifoldstepaxees(struct vec *pos, struct vec *dir, struct vec **lads, int numlads, double distance) 
{
        if (numlads == 0) {
                *((int *) 0) = 0;
        }

        struct vec *yaxisold = estimateNormal(pos, &manifold);

         /* move the vector foward in euclid */
        add_scaled_vec_ip(pos, dir, distance);

        struct vec *yaxisnew = estimateNormal(pos, &manifold);

        /* stick it to the manifold */
        add_scaled_vec_ip(pos, yaxisnew, manifold.dist(pos));

        double protamtloc = acos(dot_product_vec(yaxisold,yaxisnew));

        struct vec *protaxisloc = normalise_vec_ip(reyeet(yaxisold, yaxisnew));
        for (int i = 0; i < numlads; i++) {
                struct vec *temp = copy_vec(lads[i]);
                rotateaxis(temp, protaxisloc, protamtloc); /* change the direction */
                if (!vectorisnan(temp)) {
                        free(lads[i]->elements);
                        lads[i]->elements = temp->elements;
                        free(temp);
                } else {
                        free_vec(temp);
                }
        }

        free_vec(yaxisnew);
        free_vec(yaxisold);
        free_vec(protaxisloc);
}

void 
manifoldturn(struct ray *r, struct vec *v, double distance)
{

        struct vec *yaxisold = estimateNormal(r->pos, &manifold);

         /* move the vector foward in euclid */
        add_scaled_vec_ip(r->pos, r->dir, distance);

        struct vec *yaxisnew = estimateNormal(r->pos, &manifold);

        /* stick it to the manifold */
        add_scaled_vec_ip(r->pos, yaxisnew, manifold.dist(r->pos));

        double protamtloc = acos(dot_product_vec(yaxisold,yaxisnew));

        struct vec *protaxisloc = normalise_vec_ip(reyeet(yaxisold, yaxisnew));

        struct vec *temp = copy_vec(v);
        rotateaxis(temp, protaxisloc, protamtloc); /* change the direction */
        if (!vectorisnan(temp)) {
                free(v->elements);
                v->elements = temp->elements;
                free(temp);
        } else {
                free_vec(temp);
        }

        free_vec(yaxisnew);
        free_vec(yaxisold);
        free_vec(protaxisloc);
}

void 
manifoldstep(struct ray *r, double distance)
{
        manifoldturn(r, r->dir, distance);
}

void place(struct solid *v) {
        struct vec *dirs [v->pos.dimension];
        for (int d = 0; d < v->pos.dimension; d++) {
                dirs[d] = new_vec(v->pos.dimension);
                dirs[d]->elements[d] = 1;
        }
        struct vec *tdir = new_vec(v->pos.dimension);
        struct vec *tpos = new_vec(v->pos.dimension);

        for (int d = 0; d < v->pos.dimension; d++) {
                for (double yee = v->pos.elements[d]; dabs(yee) > EPSILON; yee -= dsign(yee) * EPSILON) {
                        manifoldstepaxees(tpos, dirs[d], dirs, v->pos.dimension, EPSILON);
                }
        }
        free_vec(tdir);
        free_vec(tpos);
        for (int d = 0; d < v->pos.dimension; d++) free_vec(dirs[d]);
        free(dirs);
}

struct pixel_info 
march(struct ray *r, struct object *scene)
{
        double travel_dist = 0;
        double scene_dist;
        double min_dist = DRAW_DIST;
        int i;
        int fligs = 0;
        struct colour out = (struct colour) {.sp = CS_RGB};
        for (i = 0; (i < MAX_ITERATIONS) && (travel_dist < DRAW_DIST); i++) {
                /* calculate the distance to the scene */
                scene_dist = solid_dist(&(scene->sol), r->pos);

                if (scene_dist < EPSILON) { /* we've hit an object */
                        out = solid_col(scene, r);
                        fligs |= 0x01;
                        break;
                }

                if (min_dist > scene_dist)
                        min_dist = scene_dist;

                /* step foward the calculated distance */
                manifoldstep(r, scene_dist);
                travel_dist += scene_dist;
        }

        /* no colour reached */
        return (struct pixel_info) {
                .flags = fligs, 
                .iterations = i, 
                .col = out, 
                .travel_dist = travel_dist, 
                .scene_dist = min_dist
                }; 
}


union badpixelformat {
    struct {
        Uint8 b;
        Uint8 g;
        Uint8 r;
        Uint8 a;
    };
    Uint32 pixel;
};

Uint32 get_stl_colour(struct colour *cl) {
    struct colour c = get_rgb(*cl);
    union badpixelformat p;
    p.r = c.r;
    p.g = c.g;
    p.b = c.b;
    p.a = c.a;
    return p.pixel;
}

Uint32
process_pixel(int i, int j)
{
        struct ray r = (struct ray) {
            .pos = new_vec(4),
            .dir = normalise_vec_ip(new_vec4(i  - B_INTERNAL_WIDTH/2, j - B_INTERNAL_HEIGHT/2, 50, 0))
        };

        struct pixel_info p = march(&r, scene_object);
        
        // p.col.r += p.travel_dist;
        if (!(p.flags & 0x01)) {
                p.col.b = 255;
                p.col.r = j * 7;
                p.col.g += (16.0 / p.scene_dist);
                p.col.b += (16.0 / p.scene_dist);
        } else {
         //       p.col.r -= p.iterations;
         //       p.col.g -= p.iterations;
        //        p.col.b -= p.iterations;
        }

        double fade_intensity = 50;

        if (p.travel_dist < DRAW_DIST) {
            p.col.r -= fade_intensity * p.travel_dist / DRAW_DIST;
            p.col.g -= fade_intensity * p.travel_dist / DRAW_DIST;
            p.col.b -= fade_intensity * p.travel_dist / DRAW_DIST;
            
        }

        p.col.r = clamp(p.col.r, 0, 255);
        p.col.g = clamp(p.col.g, 0, 255);
        p.col.b = clamp(p.col.b, 0, 255);
        // p.col.g = 0;

        // printf("%d, ", p.iterations);

        /*
        if (p.col.r < 0) p.col.r = 0;
        if (p.col.g < 0) p.col.g = 0;
        if (p.col.b < 0) p.col.b = 0;
        if (p.col.r > 255) p.col.r = 255;
        if (p.col.g > 255) p.col.g = 255;
        if (p.col.b > 255) p.col.b = 255;
        */

        // p.col.b = 255.0 / p.scene_dist;
        // if (p.col.b > 255) p.col.b = 255;

        free_vec(r.pos);
        free_vec(r.dir);

        return get_stl_colour(&p.col);
}