BKE_kelvinlet.h

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/* SPDX-FileCopyrightText: Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */
#pragma once

 
/* Regularized Kelvinlets: Sculpting Brushes based on Fundamental Solutions of Elasticity
 * Pixar Technical Memo #17-03 */
 
#define KELVINLET_MAX_ITERATIONS 3
 
typedef struct KelvinletParams {
  float a;
  float b;
  float c;
 
  float f;
 
  float radius_scaled[KELVINLET_MAX_ITERATIONS];
} KelvinletParams;
 
/* Initialize KelvinletParams to store the parameters that will affect the deformation produced by
 * a Kelvinlet */
void BKE_kelvinlet_init_params(
    KelvinletParams *params, float radius, float force, float shear_modulus, float poisson_ratio);
 
/* Regularized Kelvinlets */
/* All these functions output the displacement that should be applied to each element. */
/* The initial coordinates of that element should not be modified during the transformation */
void BKE_kelvinlet_grab(float radius_elem_disp[3],
                        const KelvinletParams *params,
                        const float elem_orig_co[3],
                        const float brush_location[3],
                        const float brush_delta[3]);
void BKE_kelvinlet_grab_biscale(float radius_elem_disp[3],
                                const KelvinletParams *params,
                                const float elem_orig_co[3],
                                const float brush_location[3],
                                const float brush_delta[3]);
void BKE_kelvinlet_grab_triscale(float radius_elem_disp[3],
                                 const KelvinletParams *params,
                                 const float elem_orig_co[3],
                                 const float brush_location[3],
                                 const float brush_delta[3]);
void BKE_kelvinlet_scale(float radius_elem_disp[3],
                         const KelvinletParams *params,
                         const float elem_orig_co[3],
                         const float brush_location[3],
                         const float surface_normal[3]);
void BKE_kelvinlet_twist(float radius_elem_disp[3],
                         const KelvinletParams *params,
                         const float elem_orig_co[3],
                         const float brush_location[3],
                         const float surface_normal[3]);