path: root/dimension/realize.c

/*************************************************************************
 * Copyright (C) 2009 Tavian Barnes <tavianator@gmail.com>               *
 *                                                                       *
 * This file is part of Dimension.                                       *
 *                                                                       *
 * Dimension is free software; you can redistribute it and/or modify it  *
 * under the terms of the GNU General Public License as published by the *
 * Free Software Foundation; either version 3 of the License, or (at     *
 * your option) any later version.                                       *
 *                                                                       *
 * Dimension is distributed in the hope that it will be useful, but      *
 * WITHOUT ANY WARRANTY; without even the implied warranty of            *
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU     *
 * General Public License for more details.                              *
 *                                                                       *
 * You should have received a copy of the GNU General Public License     *
 * along with this program.  If not, see <http://www.gnu.org/licenses/>. *
 *************************************************************************/

#define _GNU_SOURCE /* For fmemopen */

#include "realize.h"
#include "parse.h"
#include "utility.h"
#include <math.h>
#include <stdio.h>
#include <stdbool.h>

static double
dmnsn_realize_float(dmnsn_astnode astnode)
{
  switch (astnode.type) {
  case DMNSN_AST_FLOAT:
    return *(double *)astnode.ptr;
  case DMNSN_AST_INTEGER:
    return *(long *)astnode.ptr;

  default:
    dmnsn_error(DMNSN_SEVERITY_HIGH, "Invalid float.");
    return 0; /* Silence compiler warning */
  }
}

static dmnsn_vector
dmnsn_realize_vector(dmnsn_astnode astnode)
{
  if (astnode.type != DMNSN_AST_VECTOR) {
    dmnsn_error(DMNSN_SEVERITY_HIGH, "Expected a vector.");
  }

  dmnsn_astnode xnode, ynode, znode;
  dmnsn_array_get(astnode.children, 0, &xnode);
  dmnsn_array_get(astnode.children, 1, &ynode);
  dmnsn_array_get(astnode.children, 2, &znode);

  double x = dmnsn_realize_float(xnode),
         y = dmnsn_realize_float(ynode),
         z = dmnsn_realize_float(znode);

  return dmnsn_new_vector(x, y, z);
}

static dmnsn_color
dmnsn_realize_color(dmnsn_astnode astnode)
{
  if (astnode.type != DMNSN_AST_COLOR) {
    dmnsn_error(DMNSN_SEVERITY_HIGH, "Expected a color.");
  }

  dmnsn_astnode rnode, gnode, bnode, fnode, tnode;
  dmnsn_array_get(astnode.children, 0, &rnode);
  dmnsn_array_get(astnode.children, 1, &gnode);
  dmnsn_array_get(astnode.children, 2, &bnode);
  dmnsn_array_get(astnode.children, 3, &fnode);
  dmnsn_array_get(astnode.children, 4, &tnode);

  double r = dmnsn_realize_float(rnode),
         g = dmnsn_realize_float(gnode),
         b = dmnsn_realize_float(bnode),
         f = dmnsn_realize_float(fnode),
         t = dmnsn_realize_float(tnode);

  dmnsn_sRGB sRGB = { .R = r, .G = g, .B = b };
  dmnsn_color color = dmnsn_color_from_sRGB(sRGB);
  color.filter = f;
  color.trans  = t;

  return color;
}

static dmnsn_matrix
dmnsn_realize_rotation(dmnsn_astnode astnode)
{
  if (astnode.type != DMNSN_AST_ROTATION) {
    dmnsn_error(DMNSN_SEVERITY_HIGH, "Expected a rotation.");
  }

  const double deg2rad = atan(1.0)/45.0;

  dmnsn_astnode angle_node;
  dmnsn_array_get(astnode.children, 0, &angle_node);

  dmnsn_vector angle = dmnsn_vector_mul(
    deg2rad,
    dmnsn_realize_vector(angle_node)
  );

  dmnsn_matrix trans = dmnsn_rotation_matrix(
    dmnsn_new_vector(angle.x, 0.0, 0.0)
  );
  trans = dmnsn_matrix_mul(
    dmnsn_rotation_matrix(dmnsn_new_vector(0.0, angle.y, 0.0)),
    trans
  );
  trans = dmnsn_matrix_mul(
    dmnsn_rotation_matrix(dmnsn_new_vector(0.0, 0.0, angle.z)),
    trans
  );

  return trans;
}

static dmnsn_matrix
dmnsn_realize_scale(dmnsn_astnode astnode)
{
  if (astnode.type != DMNSN_AST_SCALE) {
    dmnsn_error(DMNSN_SEVERITY_HIGH, "Expected a scale.");
  }

  dmnsn_astnode scale_node;
  dmnsn_array_get(astnode.children, 0, &scale_node);
  dmnsn_vector scale = dmnsn_realize_vector(scale_node);

  return dmnsn_scale_matrix(scale);
}

static dmnsn_matrix
dmnsn_realize_translation(dmnsn_astnode astnode)
{
  if (astnode.type != DMNSN_AST_TRANSLATION) {
    dmnsn_error(DMNSN_SEVERITY_HIGH, "Expected a translation.");
  }

  dmnsn_astnode trans_node;
  dmnsn_array_get(astnode.children, 0, &trans_node);
  dmnsn_vector trans = dmnsn_realize_vector(trans_node);

  return dmnsn_translation_matrix(trans);
}

static dmnsn_camera *
dmnsn_realize_camera(dmnsn_astnode astnode)
{
  const double deg2rad = atan(1.0)/45.0;

  dmnsn_astnode_type camera_type = DMNSN_AST_PERSPECTIVE;
  dmnsn_vector location  = dmnsn_new_vector(0.0, 0.0, 0.0);
  dmnsn_vector direction = dmnsn_new_vector(0.0, 0.0, 1.0);
  dmnsn_vector right     = dmnsn_new_vector(4.0/3.0, 0.0, 0.0);
  dmnsn_vector up        = dmnsn_new_vector(0.0, 1.0, 0.0);
  dmnsn_vector sky       = dmnsn_new_vector(0.0, 1.0, 0.0);
  dmnsn_matrix trans     = dmnsn_identity_matrix();

  dmnsn_camera *camera = NULL;

  unsigned int i;
  for (i = 0; i < dmnsn_array_size(astnode.children); ++i) {
    dmnsn_astnode item;
    dmnsn_array_get(astnode.children, i, &item);

    switch (item.type) {
    /* Camera types */
    case DMNSN_AST_PERSPECTIVE:
      camera_type = item.type;
      break;

    /* Camera vectors */
    case DMNSN_AST_LOCATION:
      dmnsn_array_get(item.children, 0, &item);
      location = dmnsn_realize_vector(item);
      break;
    case DMNSN_AST_RIGHT:
      dmnsn_array_get(item.children, 0, &item);
      right = dmnsn_realize_vector(item);
      break;
    case DMNSN_AST_UP:
      dmnsn_array_get(item.children, 0, &item);
      right = dmnsn_realize_vector(item);
      break;
    case DMNSN_AST_SKY:
      dmnsn_array_get(item.children, 0, &item);
      sky = dmnsn_realize_vector(item);
      break;
    case DMNSN_AST_DIRECTION:
      dmnsn_array_get(item.children, 0, &item);
      direction = dmnsn_realize_vector(item);
      break;

    /* Camera modifiers */

    case DMNSN_AST_LOOK_AT:
      {
        dmnsn_array_get(item.children, 0, &item);
        dmnsn_vector look_at = dmnsn_realize_vector(item);

        /* Line the camera up with the sky */

        dmnsn_matrix sky1 = dmnsn_rotation_matrix(
          dmnsn_vector_mul(
            dmnsn_vector_axis_angle(up, sky, direction),
            dmnsn_vector_normalize(direction)
          )
        );
        up    = dmnsn_matrix_vector_mul(sky1, up);
        right = dmnsn_matrix_vector_mul(sky1, right);

        dmnsn_matrix sky2 = dmnsn_rotation_matrix(
          dmnsn_vector_mul(
            dmnsn_vector_axis_angle(up, sky, right),
            dmnsn_vector_normalize(right)
          )
        );
        up        = dmnsn_matrix_vector_mul(sky2, up);
        direction = dmnsn_matrix_vector_mul(sky2, direction);

        /* Line up the camera with the look_at */

        look_at = dmnsn_vector_sub(look_at, location);
        dmnsn_matrix look_at1 = dmnsn_rotation_matrix(
          dmnsn_vector_mul(
            dmnsn_vector_axis_angle(direction, look_at, up),
            dmnsn_vector_normalize(up)
          )
        );
        right     = dmnsn_matrix_vector_mul(look_at1, right);
        direction = dmnsn_matrix_vector_mul(look_at1, direction);

        dmnsn_matrix look_at2 = dmnsn_rotation_matrix(
          dmnsn_vector_mul(
            dmnsn_vector_axis_angle(direction, look_at, right),
            dmnsn_vector_normalize(right)
          )
        );
        up        = dmnsn_matrix_vector_mul(look_at2, up);
        direction = dmnsn_matrix_vector_mul(look_at2, direction);

        break;
      }

    case DMNSN_AST_ANGLE:
      {
        dmnsn_array_get(item.children, 0, &item);
        double angle = deg2rad*dmnsn_realize_float(item);
        direction = dmnsn_vector_mul(
          0.5*dmnsn_vector_norm(right)/tan(angle/2.0),
          dmnsn_vector_normalize(direction)
        );
        break;
      }

    /* Transformations */
    case DMNSN_AST_ROTATION:
      trans = dmnsn_matrix_mul(dmnsn_realize_rotation(item), trans);
      break;
    case DMNSN_AST_SCALE:
      trans = dmnsn_matrix_mul(dmnsn_realize_scale(item), trans);
      break;
    case DMNSN_AST_TRANSLATION:
      trans = dmnsn_matrix_mul(dmnsn_realize_translation(item), trans);
      break;

    default:
      dmnsn_error(DMNSN_SEVERITY_HIGH, "Invalid camera item.");
      break;
    }
  }

  switch (camera_type) {
  case DMNSN_AST_PERSPECTIVE:
    {
      /* These multiplications are in right-to-left order so that user
         transformations happen after camera alignment */

      trans = dmnsn_matrix_mul(trans, dmnsn_translation_matrix(location));

      /* Align y with `up' */

      dmnsn_matrix align = dmnsn_rotation_matrix(
        dmnsn_vector_mul(
          dmnsn_vector_axis_angle(dmnsn_y, up, dmnsn_z),
          dmnsn_z
        )
      );

      dmnsn_vector x = dmnsn_matrix_vector_mul(align, dmnsn_x);
      dmnsn_vector y = dmnsn_matrix_vector_mul(align, dmnsn_y);

      align = dmnsn_matrix_mul(
        dmnsn_rotation_matrix(
          dmnsn_vector_mul(
            dmnsn_vector_axis_angle(y, up, x),
            x
          )
        ),
        align
      );

      /* Align x with `right' */

      align = dmnsn_matrix_mul(
        dmnsn_rotation_matrix(
          dmnsn_vector_mul(
            dmnsn_vector_axis_angle(x, right, up),
            dmnsn_vector_normalize(up)
          )
        ),
        align
      );

      trans = dmnsn_matrix_mul(trans, align);

      /* Scale the camera with `up', `right', and `direction' */
      trans = dmnsn_matrix_mul(
        trans,
        dmnsn_scale_matrix(
          dmnsn_new_vector(
            dmnsn_vector_norm(right),
            dmnsn_vector_norm(up),
            dmnsn_vector_norm(direction)
          )
        )
      );

      camera = dmnsn_new_perspective_camera();
      dmnsn_set_perspective_camera_trans(camera, trans);
      break;
    }

  default:
    dmnsn_error(DMNSN_SEVERITY_HIGH, "Unsupported camera type.");
  }

  return camera;
}

static dmnsn_pigment *
dmnsn_realize_pigment(dmnsn_astnode astnode)
{
  if (astnode.type != DMNSN_AST_PIGMENT) {
    dmnsn_error(DMNSN_SEVERITY_HIGH, "Expected a pigment.");
  }

  dmnsn_pigment *pigment = NULL;

  dmnsn_astnode color_node;
  dmnsn_array_get(astnode.children, 0, &color_node);

  dmnsn_color color;
  switch (color_node.type) {
  case DMNSN_AST_NONE:
    break;

  case DMNSN_AST_COLOR:
    color = dmnsn_realize_color(color_node);
    pigment = dmnsn_new_solid_pigment(color);
    if (!pigment) {
      dmnsn_error(DMNSN_SEVERITY_HIGH, "Couldn't create pigment.");
    }
    break;

  default:
    dmnsn_error(DMNSN_SEVERITY_HIGH, "Invalid pigment color.");
  }

  return pigment;
}

static dmnsn_finish *
dmnsn_realize_reflection(dmnsn_astnode astnode)
{
  if (astnode.type != DMNSN_AST_REFLECTION) {
    dmnsn_error(DMNSN_SEVERITY_HIGH, "Expected a reflection.");
  }

  dmnsn_astnode min_node, max_node;
  dmnsn_array_get(astnode.children, 0, &min_node);
  dmnsn_array_get(astnode.children, 1, &max_node);

  dmnsn_color min = dmnsn_realize_color(min_node);
  dmnsn_color max = dmnsn_realize_color(max_node);

  double falloff = 1.0;

  dmnsn_astnode items;
  dmnsn_array_get(astnode.children, 2, &items);

  unsigned int i;
  for (i = 0; i < dmnsn_array_size(items.children); ++i) {
    dmnsn_astnode item, child;
    dmnsn_array_get(items.children, i, &item);

    switch (item.type) {
    case DMNSN_AST_FALLOFF:
      dmnsn_array_get(item.children, 0, &child);
      falloff = dmnsn_realize_float(child);
      break;

    default:
      dmnsn_error(DMNSN_SEVERITY_HIGH, "Invalid reflection item.");
    }
  }

  dmnsn_finish *reflection = dmnsn_new_reflective_finish(min, max, falloff);
  if (!reflection) {
    dmnsn_error(DMNSN_SEVERITY_HIGH, "Couldn't allocate a reflection.");
  }

  return reflection;
}

static dmnsn_finish *
dmnsn_realize_finish(dmnsn_astnode astnode)
{
  if (astnode.type != DMNSN_AST_FINISH) {
    dmnsn_error(DMNSN_SEVERITY_HIGH, "Expected a finish.");
  }

  dmnsn_finish *finish = dmnsn_new_finish();

  dmnsn_color ambient = dmnsn_black;
  bool ambient_set = false;

  double diffuse = 0.0;
  bool diffuse_set = false;

  double phong = 0.0;
  double phong_size = 40.0;

  dmnsn_finish *reflection = NULL;

  unsigned int i;
  for (i = 0; i < dmnsn_array_size(astnode.children); ++i) {
    dmnsn_astnode item, child;
    dmnsn_array_get(astnode.children, i, &item);

    switch (item.type) {
    case DMNSN_AST_AMBIENT:
      dmnsn_array_get(item.children, 0, &child);
      ambient = dmnsn_realize_color(child);
      ambient_set = true;
      break;

    case DMNSN_AST_DIFFUSE:
      dmnsn_array_get(item.children, 0, &child);
      diffuse = dmnsn_realize_float(child);
      diffuse_set = true;
      break;

    case DMNSN_AST_PHONG:
      dmnsn_array_get(item.children, 0, &child);
      phong = dmnsn_realize_float(child);
      break;
    case DMNSN_AST_PHONG_SIZE:
      dmnsn_array_get(item.children, 0, &child);
      phong_size = dmnsn_realize_float(child);
      break;

    case DMNSN_AST_REFLECTION:
      dmnsn_delete_finish(reflection);
      reflection = dmnsn_realize_reflection(item);
      break;

    default:
      dmnsn_error(DMNSN_SEVERITY_HIGH, "Invalid finish item.");
    }
  }

  if (ambient_set) {
    finish = dmnsn_new_finish_combination(
      dmnsn_new_ambient_finish(ambient),
      finish
    );
  }

  if (diffuse_set) {
    finish = dmnsn_new_finish_combination(
      dmnsn_new_diffuse_finish(diffuse),
      finish
    );
  }

  if (phong) {
    finish = dmnsn_new_finish_combination(
      dmnsn_new_phong_finish(phong, phong_size),
      finish
    );
  }

  if (reflection) {
    finish = dmnsn_new_finish_combination(reflection, finish);
  }

  if (!finish) {
    dmnsn_error(DMNSN_SEVERITY_HIGH, "Couldn't allocate finish.");
  }

  return finish;
}

static dmnsn_texture *
dmnsn_realize_texture(dmnsn_astnode astnode)
{
  if (astnode.type != DMNSN_AST_TEXTURE) {
    dmnsn_error(DMNSN_SEVERITY_HIGH, "Expected a texture.");
  }

  dmnsn_texture *texture = dmnsn_new_texture();
  if (!texture) {
    dmnsn_error(DMNSN_SEVERITY_HIGH, "Couldn't allocate texture.");
  }

  unsigned int i;
  for (i = 0; i < dmnsn_array_size(astnode.children); ++i) {
    dmnsn_astnode modifier;
    dmnsn_array_get(astnode.children, i, &modifier);

    switch (modifier.type) {
    case DMNSN_AST_PIGMENT:
      dmnsn_delete_pigment(texture->pigment);
      texture->pigment = dmnsn_realize_pigment(modifier);
      break;

    case DMNSN_AST_FINISH:
      dmnsn_delete_finish(texture->finish);
      texture->finish = dmnsn_realize_finish(modifier);
      break;

    default:
      dmnsn_error(DMNSN_SEVERITY_HIGH, "Invalid texture item.");
    }
  }

  return texture;
}

static void
dmnsn_realize_object_modifiers(dmnsn_astnode astnode, dmnsn_object *object)
{
  if (astnode.type != DMNSN_AST_OBJECT_MODIFIERS) {
    dmnsn_error(DMNSN_SEVERITY_HIGH, "Expected object modifiers.");
  }

  unsigned int i;
  for (i = 0; i < dmnsn_array_size(astnode.children); ++i) {
    dmnsn_astnode modifier;
    dmnsn_array_get(astnode.children, i, &modifier);

    switch (modifier.type) {
    case DMNSN_AST_ROTATION:
      object->trans = dmnsn_matrix_mul(
        dmnsn_realize_rotation(modifier),
        object->trans
      );
      break;
    case DMNSN_AST_SCALE:
      object->trans = dmnsn_matrix_mul(
        dmnsn_realize_scale(modifier),
        object->trans
      );
      break;
    case DMNSN_AST_TRANSLATION:
      object->trans = dmnsn_matrix_mul(
        dmnsn_realize_translation(modifier),
        object->trans
      );
      break;

    case DMNSN_AST_TEXTURE:
      dmnsn_delete_texture(object->texture);
      object->texture = dmnsn_realize_texture(modifier);
      break;

    default:
      dmnsn_error(DMNSN_SEVERITY_HIGH, "Invalid object modifier.");
    }
  }
}

static dmnsn_object *
dmnsn_realize_box(dmnsn_astnode astnode)
{
  if (astnode.type != DMNSN_AST_BOX) {
    dmnsn_error(DMNSN_SEVERITY_HIGH, "Expected a box.");
  }

  dmnsn_astnode corner1, corner2;
  dmnsn_array_get(astnode.children, 0, &corner1);
  dmnsn_array_get(astnode.children, 1, &corner2);

  dmnsn_vector x1 = dmnsn_realize_vector(corner1),
               x2 = dmnsn_realize_vector(corner2);

  dmnsn_object *box = dmnsn_new_cube();
  if (!box) {
    dmnsn_error(DMNSN_SEVERITY_HIGH, "Couldn't allocate box.");
  }

  box->trans = dmnsn_scale_matrix(
    dmnsn_new_vector(fabs(x2.x - x1.x)/2.0,
                     fabs(x2.y - x1.y)/2.0,
                     fabs(x2.z - x1.z)/2.0)
  );
  box->trans = dmnsn_matrix_mul(
    dmnsn_translation_matrix(dmnsn_new_vector((x2.x + x1.x)/2.0,
                                              (x2.y + x1.y)/2.0,
                                              (x2.z + x1.z)/2.0)),
    box->trans
  );

  dmnsn_astnode modifiers;
  dmnsn_array_get(astnode.children, 2, &modifiers);
  dmnsn_realize_object_modifiers(modifiers, box);

  return box;
}

static dmnsn_light *
dmnsn_realize_light_source(dmnsn_astnode astnode)
{
  if (astnode.type != DMNSN_AST_LIGHT_SOURCE) {
    dmnsn_error(DMNSN_SEVERITY_HIGH, "Expected a light source.");
  }

  dmnsn_astnode point, color_node;
  dmnsn_array_get(astnode.children, 0, &point);
  dmnsn_array_get(astnode.children, 1, &color_node);

  dmnsn_vector x0 = dmnsn_realize_vector(point);
  dmnsn_color color = dmnsn_realize_color(color_node);

  dmnsn_light *light = dmnsn_new_point_light(x0, color);
  if (!light) {
    dmnsn_error(DMNSN_SEVERITY_HIGH, "Couldn't allocate light.");
  }

  return light;
}

static dmnsn_object *
dmnsn_realize_sphere(dmnsn_astnode astnode)
{
  if (astnode.type != DMNSN_AST_SPHERE) {
    dmnsn_error(DMNSN_SEVERITY_HIGH, "Expected a sphere.");
  }

  dmnsn_astnode center, radius;
  dmnsn_array_get(astnode.children, 0, &center);
  dmnsn_array_get(astnode.children, 1, &radius);

  dmnsn_vector x0 = dmnsn_realize_vector(center);
  double r = dmnsn_realize_float(radius);

  dmnsn_object *sphere = dmnsn_new_sphere();
  if (!sphere) {
    dmnsn_error(DMNSN_SEVERITY_HIGH, "Couldn't allocate sphere.");
  }

  sphere->trans = dmnsn_scale_matrix(dmnsn_new_vector(r, r, r));
  sphere->trans = dmnsn_matrix_mul(dmnsn_translation_matrix(x0), sphere->trans);

  dmnsn_astnode modifiers;
  dmnsn_array_get(astnode.children, 2, &modifiers);
  dmnsn_realize_object_modifiers(modifiers, sphere);

  return sphere;
}

static dmnsn_scene *
dmnsn_realize_astree(const dmnsn_astree *astree)
{
  dmnsn_scene *scene = dmnsn_new_scene();
  if (!scene) {
    return NULL;
  }

  /* Default finish */
  scene->default_texture->finish = dmnsn_new_finish_combination(
    dmnsn_new_ambient_finish(
      dmnsn_color_mul(0.1, dmnsn_white)
    ),
    dmnsn_new_diffuse_finish(0.6)
  );
  if (!scene->default_texture->finish) {
    dmnsn_delete_scene(scene);
    return NULL;
  }

  /* Background color */
  scene->background = dmnsn_black;

  /* Create the default perspective camera */
  scene->camera = dmnsn_new_perspective_camera();
  if (!scene->camera) {
    dmnsn_delete_scene(scene);
    return NULL;
  }

  /*
   * Now parse the abstract syntax tree
   */

  dmnsn_astnode astnode;
  unsigned int i;

  for (i = 0; i < dmnsn_array_size(astree); ++i) {
    dmnsn_array_get(astree, i, &astnode);

    dmnsn_light  *light;
    dmnsn_object *object;
    switch (astnode.type) {
    case DMNSN_AST_CAMERA:
      dmnsn_delete_camera(scene->camera);
      scene->camera = dmnsn_realize_camera(astnode);
      break;

    case DMNSN_AST_BACKGROUND:
      dmnsn_array_get(astnode.children, 0, &astnode);
      scene->background = dmnsn_realize_color(astnode);
      break;

    case DMNSN_AST_BOX:
      object = dmnsn_realize_box(astnode);
      dmnsn_array_push(scene->objects, &object);
      break;

    case DMNSN_AST_LIGHT_SOURCE:
      light = dmnsn_realize_light_source(astnode);
      dmnsn_array_push(scene->lights, &light);
      break;

    case DMNSN_AST_SPHERE:
      object = dmnsn_realize_sphere(astnode);
      dmnsn_array_push(scene->objects, &object);
      break;

    default:
      dmnsn_error(DMNSN_SEVERITY_HIGH, "Unrecognised syntax element.");
    }
  }

  return scene;
}

dmnsn_scene *
dmnsn_realize(FILE *file, dmnsn_symbol_table *symtable)
{
  if (!symtable) {
    symtable = dmnsn_new_symbol_table();
  }

  dmnsn_astree *astree = dmnsn_parse(file, symtable);
  if (!astree) {
    return NULL;
  }

  dmnsn_scene *scene = dmnsn_realize_astree(astree);

  dmnsn_delete_astree(astree);
  return scene;
}

dmnsn_scene *
dmnsn_realize_string(const char *str, dmnsn_symbol_table *symtable)
{
  if (!symtable) {
    symtable = dmnsn_new_symbol_table();
  }
  if (!dmnsn_find_symbol(symtable, "__file__")) {
    dmnsn_declare_symbol(symtable, "__file__",
                         dmnsn_new_ast_string("<string>"));
  }

  FILE *file = fmemopen((void *)str, strlen(str), "r");
  if (!file) {
    return NULL;
  }

  dmnsn_scene *scene = dmnsn_realize(file, symtable);

  fclose(file);
  return scene;
}