tornavis/source/blender/blenlib/intern/uvproject.c

/* SPDX-FileCopyrightText: 2023 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */

/** \file
 * \ingroup bli
 */

#include <math.h>

#include "MEM_guardedalloc.h"

#include "DNA_camera_types.h"
#include "DNA_object_types.h"

#include "BLI_math_matrix.h"
#include "BLI_math_rotation.h"
#include "BLI_math_vector.h"
#include "BLI_uvproject.h"

typedef struct ProjCameraInfo {
  float camangle;
  float camsize;
  float xasp, yasp;
  float shiftx, shifty;
  float rotmat[4][4];
  float caminv[4][4];
  bool do_persp, do_pano, do_rotmat;
} ProjCameraInfo;

void BLI_uvproject_from_camera(float target[2], float source[3], ProjCameraInfo *uci)
{
  float pv4[4];

  copy_v3_v3(pv4, source);
  pv4[3] = 1.0;

  /* rotmat is the object matrix in this case */
  if (uci->do_rotmat) {
    mul_m4_v4(uci->rotmat, pv4);
  }

  /* caminv is the inverse camera matrix */
  mul_m4_v4(uci->caminv, pv4);

  if (uci->do_pano) {
    float angle = atan2f(pv4[0], -pv4[2]) / ((float)M_PI * 2.0f); /* angle around the camera */
    if (uci->do_persp == false) {
      target[0] = angle; /* no correct method here, just map to  0-1 */
      target[1] = pv4[1] / uci->camsize;
    }
    else {
      float vec2d[2]; /* 2D position from the camera */
      vec2d[0] = pv4[0];
      vec2d[1] = pv4[2];
      target[0] = angle * ((float)M_PI / uci->camangle);
      target[1] = pv4[1] / (len_v2(vec2d) * (uci->camsize * 2.0f));
    }
  }
  else {
    if (pv4[2] == 0.0f) {
      pv4[2] = 0.00001f; /* don't allow div by 0 */
    }

    if (uci->do_persp == false) {
      target[0] = (pv4[0] / uci->camsize);
      target[1] = (pv4[1] / uci->camsize);
    }
    else {
      target[0] = (-pv4[0] * ((1.0f / uci->camsize) / pv4[2])) / 2.0f;
      target[1] = (-pv4[1] * ((1.0f / uci->camsize) / pv4[2])) / 2.0f;
    }
  }

  target[0] *= uci->xasp;
  target[1] *= uci->yasp;

  /* adds camera shift + 0.5 */
  target[0] += uci->shiftx;
  target[1] += uci->shifty;
}

void BLI_uvproject_from_view(float target[2],
                             float source[3],
                             float persmat[4][4],
                             float rotmat[4][4],
                             float winx,
                             float winy)
{
  float pv4[4], x = 0.0, y = 0.0;

  copy_v3_v3(pv4, source);
  pv4[3] = 1.0;

  /* rotmat is the object matrix in this case */
  mul_m4_v4(rotmat, pv4);

  /* almost ED_view3d_project_short */
  mul_m4_v4(persmat, pv4);
  if (fabsf(pv4[3]) > 0.00001f) { /* avoid division by zero */
    target[0] = winx / 2.0f + (winx / 2.0f) * pv4[0] / pv4[3];
    target[1] = winy / 2.0f + (winy / 2.0f) * pv4[1] / pv4[3];
  }
  else {
    /* scaling is lost but give a valid result */
    target[0] = winx / 2.0f + (winx / 2.0f) * pv4[0];
    target[1] = winy / 2.0f + (winy / 2.0f) * pv4[1];
  }

  /* v3d->persmat seems to do this funky scaling */
  if (winx > winy) {
    y = (winx - winy) / 2.0f;
    winy = winx;
  }
  else {
    x = (winy - winx) / 2.0f;
    winx = winy;
  }

  target[0] = (x + target[0]) / winx;
  target[1] = (y + target[1]) / winy;
}

ProjCameraInfo *BLI_uvproject_camera_info(Object *ob, float rotmat[4][4], float winx, float winy)
{
  ProjCameraInfo uci;
  Camera *camera = ob->data;

  uci.do_pano = (camera->type == CAM_PANO);
  uci.do_persp = (camera->type == CAM_PERSP);

  uci.camangle = focallength_to_fov(camera->lens, camera->sensor_x) / 2.0f;
  uci.camsize = uci.do_persp ? tanf(uci.camangle) : camera->ortho_scale;

  /* account for scaled cameras */
  copy_m4_m4(uci.caminv, ob->object_to_world);
  normalize_m4(uci.caminv);

  if (invert_m4(uci.caminv)) {
    ProjCameraInfo *uci_pt;

    /* normal projection */
    if (rotmat) {
      copy_m4_m4(uci.rotmat, rotmat);
      uci.do_rotmat = true;
    }
    else {
      uci.do_rotmat = false;
    }

    /* also make aspect ratio adjustment factors */
    if (winx > winy) {
      uci.xasp = 1.0f;
      uci.yasp = winx / winy;
    }
    else {
      uci.xasp = winy / winx;
      uci.yasp = 1.0f;
    }

    /* include 0.5f here to move the UVs into the center */
    uci.shiftx = 0.5f - (camera->shiftx * uci.xasp);
    uci.shifty = 0.5f - (camera->shifty * uci.yasp);

    uci_pt = MEM_mallocN(sizeof(ProjCameraInfo), "ProjCameraInfo");
    *uci_pt = uci;
    return uci_pt;
  }

  return NULL;
}

void BLI_uvproject_from_view_ortho(float target[2], float source[3], const float rotmat[4][4])
{
  float pv[3];

  mul_v3_m4v3(pv, rotmat, source);

  /* ortho projection */
  target[0] = -pv[0];
  target[1] = pv[2];
}

void BLI_uvproject_camera_info_scale(ProjCameraInfo *uci, float scale_x, float scale_y)
{
  uci->xasp *= scale_x;
  uci->yasp *= scale_y;
}