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ies.cpp
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ies.cpp
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/* SPDX-FileCopyrightText: 2011-2022 Blender Foundation
*
* SPDX-License-Identifier: Apache-2.0 */
#include <algorithm>
#include "util/foreach.h"
#include "util/ies.h"
#include "util/math.h"
#include "util/string.h"
CCL_NAMESPACE_BEGIN
// NOTE: For some reason gcc-7.2 does not instantiate this version of the
// allocator here (used in IESTextParser). Works fine for gcc-6, gcc-7.3 and gcc-8.
//
// TODO(sergey): Get to the root of this issue, or confirm this is a compiler
// issue.
template class GuardedAllocator<char>;
bool IESFile::load(const string &ies)
{
clear();
if (!parse(ies) || !process()) {
clear();
return false;
}
return true;
}
void IESFile::clear()
{
intensity.clear();
v_angles.clear();
h_angles.clear();
}
int IESFile::packed_size()
{
if (v_angles.size() && h_angles.size() > 0) {
return 2 + h_angles.size() + v_angles.size() + h_angles.size() * v_angles.size();
}
return 0;
}
void IESFile::pack(float *data)
{
if (v_angles.size() && h_angles.size()) {
*(data++) = __int_as_float(h_angles.size());
*(data++) = __int_as_float(v_angles.size());
memcpy(data, &h_angles[0], h_angles.size() * sizeof(float));
data += h_angles.size();
memcpy(data, &v_angles[0], v_angles.size() * sizeof(float));
data += v_angles.size();
for (int h = 0; h < intensity.size(); h++) {
memcpy(data, &intensity[h][0], v_angles.size() * sizeof(float));
data += v_angles.size();
}
}
}
class IESTextParser {
public:
string text;
char *data;
bool error;
IESTextParser(const string &str) : text(str), error(false)
{
std::replace(text.begin(), text.end(), ',', ' ');
data = strstr(&text[0], "\nTILT=");
}
bool eof()
{
return (data == NULL) || (data[0] == '\0');
}
bool has_error()
{
return error;
}
double get_double()
{
if (eof()) {
error = true;
return 0.0;
}
char *old_data = data;
double val = strtod(data, &data);
if (data == old_data) {
data = NULL;
error = true;
return 0.0;
}
return val;
}
long get_long()
{
if (eof()) {
error = true;
return 0;
}
char *old_data = data;
long val = strtol(data, &data, 10);
if (data == old_data) {
data = NULL;
error = true;
return 0;
}
return val;
}
};
bool IESFile::parse(const string &ies)
{
if (ies.empty()) {
return false;
}
IESTextParser parser(ies);
if (parser.eof()) {
return false;
}
/* Handle the tilt data block. */
if (strncmp(parser.data, "\nTILT=INCLUDE", 13) == 0) {
parser.data += 13;
parser.get_double(); /* Lamp to Luminaire geometry */
int num_tilt = parser.get_long(); /* Amount of tilt angles and factors */
/* Skip over angles and factors. */
for (int i = 0; i < 2 * num_tilt; i++) {
parser.get_double();
}
}
else {
/* Skip to next line. */
parser.data = strstr(parser.data + 1, "\n");
}
if (parser.eof()) {
return false;
}
parser.data++;
parser.get_long(); /* Number of lamps */
parser.get_double(); /* Lumens per lamp */
double factor = parser.get_double(); /* Candela multiplier */
int v_angles_num = parser.get_long(); /* Number of vertical angles */
int h_angles_num = parser.get_long(); /* Number of horizontal angles */
type = (IESType)parser.get_long(); /* Photometric type */
if (type != TYPE_A && type != TYPE_B && type != TYPE_C) {
return false;
}
parser.get_long(); /* Unit of the geometry data */
parser.get_double(); /* Width */
parser.get_double(); /* Length */
parser.get_double(); /* Height */
factor *= parser.get_double(); /* Ballast factor */
factor *= parser.get_double(); /* Ballast-Lamp Photometric factor */
parser.get_double(); /* Input Watts */
/* Intensity values in IES files are specified in candela (lumen/sr), a photometric quantity.
* Cycles expects radiometric quantities, though, which requires a conversion.
* However, the Luminous efficacy (ratio of lumens per Watt) depends on the spectral distribution
* of the light source since lumens take human perception into account.
* Since this spectral distribution is not known from the IES file, a typical one must be
* assumed. The D65 standard illuminant has a Luminous efficacy of 177.83, which is used here to
* convert to Watt/sr. A more advanced approach would be to add a Blackbody Temperature input to
* the node and numerically integrate the Luminous efficacy from the resulting spectral
* distribution. Also, the Watt/sr value must be multiplied by 4*pi to get the Watt value that
* Cycles expects for lamp strength. Therefore, the conversion here uses 4*pi/177.83 as a Candela
* to Watt factor.
*/
factor *= 0.0706650768394;
v_angles.reserve(v_angles_num);
for (int i = 0; i < v_angles_num; i++) {
v_angles.push_back((float)parser.get_double());
}
h_angles.reserve(h_angles_num);
for (int i = 0; i < h_angles_num; i++) {
h_angles.push_back((float)parser.get_double());
}
intensity.resize(h_angles_num);
for (int i = 0; i < h_angles_num; i++) {
intensity[i].reserve(v_angles_num);
for (int j = 0; j < v_angles_num; j++) {
intensity[i].push_back((float)(factor * parser.get_double()));
}
}
return !parser.has_error();
}
static bool angle_close(float a, float b)
{
return fabsf(a - b) < 1e-4f;
}
/* Processing functions to turn file contents into the format that Cycles expects.
* Handles type conversion (the output format is based on Type C), symmetry/mirroring,
* value shifting etc.
* Note that this code is much more forgiving than the spec. For example, in type A and B,
* the range of vertical angles officially must be either exactly 0°-90° or -90°-90°.
* However, in practice, IES files are all over the place. Therefore, the handling is as
* flexible as possible, and tries to turn any input into something useful. */
void IESFile::process_type_b()
{
/* According to the standard, Type B defines a different coordinate system where the polar axis
* is horizontal, not vertical.
* To avoid over complicating the conversion logic, we just transpose the angles and use the
* regular Type A/C coordinate system. Users can just rotate the light to get the "proper"
* orientation. */
vector<vector<float>> newintensity;
newintensity.resize(v_angles.size());
for (int i = 0; i < v_angles.size(); i++) {
newintensity[i].reserve(h_angles.size());
for (int j = 0; j < h_angles.size(); j++) {
newintensity[i].push_back(intensity[j][i]);
}
}
intensity.swap(newintensity);
h_angles.swap(v_angles);
if (angle_close(h_angles[0], 0.0f)) {
/* File angles cover 0°-90°. Mirror that to -90°-90°, and shift to 0°-180° to match Cycles. */
vector<float> new_h_angles;
vector<vector<float>> new_intensity;
int hnum = h_angles.size();
new_h_angles.reserve(2 * hnum - 1);
new_intensity.reserve(2 * hnum - 1);
for (int i = hnum - 1; i > 0; i--) {
new_h_angles.push_back(90.0f - h_angles[i]);
new_intensity.push_back(intensity[i]);
}
for (int i = 0; i < hnum; i++) {
new_h_angles.push_back(90.0f + h_angles[i]);
new_intensity.push_back(intensity[i]);
}
h_angles.swap(new_h_angles);
intensity.swap(new_intensity);
}
else {
/* File angles cover -90°-90°. Shift to 0°-180° to match Cycles. */
for (int i = 0; i < h_angles.size(); i++) {
h_angles[i] += 90.0f;
}
}
if (angle_close(v_angles[0], 0.0f)) {
/* File angles cover 0°-90°. Mirror that to -90°-90°, and shift to 0°-180° to match Cycles. */
vector<float> new_v_angles;
int hnum = h_angles.size();
int vnum = v_angles.size();
new_v_angles.reserve(2 * vnum - 1);
for (int i = vnum - 1; i > 0; i--) {
new_v_angles.push_back(90.0f - v_angles[i]);
}
for (int i = 0; i < vnum; i++) {
new_v_angles.push_back(90.0f + v_angles[i]);
}
for (int i = 0; i < hnum; i++) {
vector<float> new_intensity;
new_intensity.reserve(2 * vnum - 1);
for (int j = vnum - 1; j > 0; j--) {
new_intensity.push_back(intensity[i][j]);
}
new_intensity.insert(new_intensity.end(), intensity[i].begin(), intensity[i].end());
intensity[i].swap(new_intensity);
}
v_angles.swap(new_v_angles);
}
else {
/* File angles cover -90°-90°. Shift to 0°-180° to match Cycles. */
for (int i = 0; i < v_angles.size(); i++) {
v_angles[i] += 90.0f;
}
}
}
void IESFile::process_type_a()
{
/* Convert vertical angles - just a simple offset. */
for (int i = 0; i < v_angles.size(); i++) {
v_angles[i] += 90.0f;
}
vector<float> new_h_angles;
new_h_angles.reserve(h_angles.size());
vector<vector<float>> new_intensity;
new_intensity.reserve(h_angles.size());
/* Type A goes from -90° to 90°, which is mapped to 270° to 90° respectively in Type C. */
for (int i = h_angles.size() - 1; i >= 0; i--) {
new_h_angles.push_back(180.0f - h_angles[i]);
new_intensity.push_back(intensity[i]);
}
/* If the file angles start at 0°, we need to mirror around that.
* Since the negative input range (which we generate here) maps to 180° to 270°,
* it comes after the original entries in the output. */
if (angle_close(h_angles[0], 0.0f)) {
new_h_angles.reserve(2 * h_angles.size() - 1);
new_intensity.reserve(2 * h_angles.size() - 1);
for (int i = 1; i < h_angles.size(); i++) {
new_h_angles.push_back(180.0f + h_angles[i]);
new_intensity.push_back(intensity[i]);
}
}
h_angles.swap(new_h_angles);
intensity.swap(new_intensity);
}
void IESFile::process_type_c()
{
if (angle_close(h_angles[0], 90.0f)) {
/* Some files are stored from 90° to 270°, so rotate them to the regular 0°-180° range. */
for (int i = 0; i < h_angles.size(); i++) {
h_angles[i] -= 90.0f;
}
}
if (h_angles.size() == 1) {
h_angles[0] = 0.0f;
h_angles.push_back(360.0f);
intensity.push_back(intensity[0]);
}
if (angle_close(h_angles[h_angles.size() - 1], 90.0f)) {
/* Only one quadrant is defined, so we need to mirror twice (from one to two, then to four).
* Since the two->four mirroring step might also be required if we get an input of two
* quadrants, we only do the first mirror here and later do the second mirror in either case.
*/
int hnum = h_angles.size();
for (int i = hnum - 2; i >= 0; i--) {
h_angles.push_back(180.0f - h_angles[i]);
intensity.push_back(intensity[i]);
}
}
if (angle_close(h_angles[h_angles.size() - 1], 180.0f)) {
/* Mirror half to the full range. */
int hnum = h_angles.size();
for (int i = hnum - 2; i >= 0; i--) {
h_angles.push_back(360.0f - h_angles[i]);
intensity.push_back(intensity[i]);
}
}
/* Some files skip the 360° entry (contrary to standard) because it's supposed to be identical to
* the 0° entry. If the file has a discernible order in its spacing, just fix this. */
if (angle_close(h_angles[0], 0.0f) && !angle_close(h_angles[h_angles.size() - 1], 360.0f)) {
int hnum = h_angles.size();
float last_step = h_angles[hnum - 1] - h_angles[hnum - 2];
float first_step = h_angles[1] - h_angles[0];
float gap_step = 360.0f - h_angles[hnum - 1];
if (angle_close(last_step, gap_step) || angle_close(first_step, gap_step)) {
h_angles.push_back(360.0f);
intensity.push_back(intensity[0]);
}
}
}
bool IESFile::process()
{
if (h_angles.size() == 0 || v_angles.size() == 0) {
return false;
}
if (type == TYPE_A) {
process_type_a();
}
else if (type == TYPE_B) {
process_type_b();
}
else if (type == TYPE_C) {
process_type_c();
}
else {
return false;
}
/* Convert from deg to rad. */
for (int i = 0; i < v_angles.size(); i++) {
v_angles[i] *= M_PI_F / 180.f;
}
for (int i = 0; i < h_angles.size(); i++) {
h_angles[i] *= M_PI_F / 180.f;
}
return true;
}
IESFile::~IESFile()
{
clear();
}
CCL_NAMESPACE_END