96 lines
1.8 KiB
C
96 lines
1.8 KiB
C
/* SPDX-FileCopyrightText: 2011-2022 Blender Foundation
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*
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* SPDX-License-Identifier: Apache-2.0 */
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#pragma once
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#include "util/defines.h"
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CCL_NAMESPACE_BEGIN
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ccl_device_forceinline bool projection_inverse_impl(ccl_private float R[4][4],
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ccl_private float M[4][4])
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{
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/* SPDX-License-Identifier: BSD-3-Clause
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* Adapted from code:
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* Copyright (c) 2002, Industrial Light & Magic, a division of Lucas
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* Digital Ltd. LLC. All rights reserved. */
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/* forward elimination */
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for (int i = 0; i < 4; i++) {
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int pivot = i;
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float pivotsize = M[i][i];
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if (pivotsize < 0) {
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pivotsize = -pivotsize;
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}
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for (int j = i + 1; j < 4; j++) {
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float tmp = M[j][i];
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if (tmp < 0) {
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tmp = -tmp;
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}
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if (tmp > pivotsize) {
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pivot = j;
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pivotsize = tmp;
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}
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}
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if (UNLIKELY(pivotsize == 0.0f)) {
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return false;
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}
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if (pivot != i) {
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for (int j = 0; j < 4; j++) {
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float tmp;
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tmp = M[i][j];
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M[i][j] = M[pivot][j];
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M[pivot][j] = tmp;
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tmp = R[i][j];
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R[i][j] = R[pivot][j];
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R[pivot][j] = tmp;
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}
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}
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for (int j = i + 1; j < 4; j++) {
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const float f = M[j][i] / M[i][i];
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for (int k = 0; k < 4; k++) {
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M[j][k] -= f * M[i][k];
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R[j][k] -= f * R[i][k];
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}
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}
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}
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/* backward substitution */
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for (int i = 3; i >= 0; --i) {
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float f = M[i][i];
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if (UNLIKELY(f == 0.0f)) {
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return false;
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}
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for (int j = 0; j < 4; j++) {
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M[i][j] /= f;
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R[i][j] /= f;
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}
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for (int j = 0; j < i; j++) {
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f = M[j][i];
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for (int k = 0; k < 4; k++) {
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M[j][k] -= f * M[i][k];
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R[j][k] -= f * R[i][k];
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}
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}
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}
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return true;
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}
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CCL_NAMESPACE_END
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