🛠️🐜 Antkeeper superbuild with dependencies included https://antkeeper.com
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#include "tinyexr.h"
#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"
#define STB_IMAGE_WRITE_IMPLEMENTATION
#include "stb_image_write.h"
#include <array>
#include <cmath>
#include <iostream>
#include <string>
#include <vector>
// From Filament.
static inline void RGBMtoLinear(const float rgbm[4], float linear[3]) {
linear[0] = rgbm[0] * rgbm[3] * 16.0f;
linear[1] = rgbm[1] * rgbm[3] * 16.0f;
linear[2] = rgbm[2] * rgbm[3] * 16.0f;
// Gamma to linear space
linear[0] = linear[0] * linear[0];
linear[1] = linear[1] * linear[1];
linear[2] = linear[2] * linear[2];
}
static inline void LinearToRGBM(const float linear[3], float rgbm[4]) {
rgbm[0] = linear[0];
rgbm[1] = linear[1];
rgbm[2] = linear[2];
rgbm[3] = 1.0f;
// Linear to gamma space
rgbm[0] = rgbm[0] * rgbm[0];
rgbm[1] = rgbm[1] * rgbm[1];
rgbm[2] = rgbm[2] * rgbm[2];
// Set the range
rgbm[0] /= 16.0f;
rgbm[1] /= 16.0f;
rgbm[2] /= 16.0f;
float maxComponent =
std::max(std::max(rgbm[0], rgbm[1]), std::max(rgbm[2], 1e-6f));
// Don't let M go below 1 in the [0..16] range
rgbm[3] = std::max(1.0f / 16.0f, std::min(maxComponent, 1.0f));
rgbm[3] = std::ceil(rgbm[3] * 255.0f) / 255.0f;
// saturate([0.0, 1.0])
rgbm[0] = std::max(0.0f, std::min(1.0f, rgbm[0] / rgbm[3]));
rgbm[1] = std::max(0.0f, std::min(1.0f, rgbm[1] / rgbm[3]));
rgbm[2] = std::max(0.0f, std::min(1.0f, rgbm[2] / rgbm[3]));
}
static std::string GetFileExtension(const std::string& filename) {
if (filename.find_last_of(".") != std::string::npos)
return filename.substr(filename.find_last_of(".") + 1);
return "";
}
struct Image {
int width;
int height;
std::vector<float> data;
};
static bool LoadCubemaps(const std::array<std::string, 6> face_filenames,
std::array<Image, 6>* output) {
for (size_t i = 0; i < 6; i++) {
std::string ext = GetFileExtension(face_filenames[i]);
Image image;
if ((ext.compare("exr") == 0) || (ext.compare("EXR") == 0)) {
int width, height;
float* rgba;
const char* err;
int ret =
LoadEXR(&rgba, &width, &height, face_filenames[i].c_str(), &err);
if (ret != 0) {
if (err) {
std::cerr << "EXR load error: " << err << std::endl;
} else {
std::cerr << "EXR load error: code " << ret << std::endl;
}
return false;
}
image.width = width;
image.height = height;
image.data.resize(width * height * 3);
// RGBA -> RGB
for (size_t j = 0; j < size_t(width * height); j++) {
image.data[3 * j + 0] = rgba[4 * j + 0];
image.data[3 * j + 1] = rgba[4 * j + 1];
image.data[3 * j + 2] = rgba[4 * j + 2];
}
free(rgba);
(*output)[i] = std::move(image);
} else if ((ext.compare("rgbm") == 0) || (ext.compare("RGBM") == 0)) {
int width, height;
int n;
unsigned char* data = stbi_load(face_filenames[i].c_str(), &width,
&height, &n, STBI_default);
if (!data) {
std::cerr << "Failed to load file: " << face_filenames[i] << std::endl;
return false;
}
if ((n != 4)) {
std::cerr << "Not a RGBM encoded image: " << face_filenames[i]
<< std::endl;
return false;
}
image.width = width;
image.height = height;
image.data.resize(size_t(width * height));
for (size_t i = 0; i < size_t(width * height); i++) {
float rgbm[4];
// [0, 1.0]
rgbm[0] = data[4 * i + 0] / 255.0f;
rgbm[1] = data[4 * i + 1] / 255.0f;
rgbm[2] = data[4 * i + 2] / 255.0f;
rgbm[3] = data[4 * i + 3] / 255.0f;
float linear[3];
RGBMtoLinear(rgbm, linear);
image.data[3 * i + 0] = linear[0];
image.data[3 * i + 1] = linear[1];
image.data[3 * i + 2] = linear[2];
}
(*output)[i] = std::move(image);
} else {
std::cerr << "Unknown file extension : " << ext << std::endl;
return false;
}
std::cout << "Loaded " << face_filenames[i] << std::endl;
}
return true;
}
void convert_xyz_to_cube_uv(float x, float y, float z, int* index, float* u,
float* v) {
float absX = fabs(x);
float absY = fabs(y);
float absZ = fabs(z);
int isXPositive = x > 0.0f ? 1 : 0;
int isYPositive = y > 0.0f ? 1 : 0;
int isZPositive = z > 0.0f ? 1 : 0;
float maxAxis, uc, vc;
// POSITIVE X
if (isXPositive && absX >= absY && absX >= absZ) {
// u (0 to 1) goes from +z to -z
// v (0 to 1) goes from -y to +y
maxAxis = absX;
uc = -z;
vc = y;
*index = 0;
}
// NEGATIVE X
if (!isXPositive && absX >= absY && absX >= absZ) {
// u (0 to 1) goes from -z to +z
// v (0 to 1) goes from -y to +y
maxAxis = absX;
uc = z;
vc = y;
*index = 1;
}
// POSITIVE Y
if (isYPositive && absY >= absX && absY >= absZ) {
// u (0 to 1) goes from -x to +x
// v (0 to 1) goes from +z to -z
maxAxis = absY;
uc = x;
vc = -z;
*index = 2;
}
// NEGATIVE Y
if (!isYPositive && absY >= absX && absY >= absZ) {
// u (0 to 1) goes from -x to +x
// v (0 to 1) goes from -z to +z
maxAxis = absY;
uc = x;
vc = z;
*index = 3;
}
// POSITIVE Z
if (isZPositive && (absZ >= absX) && (absZ >= absY)) {
// u (0 to 1) goes from -x to +x
// v (0 to 1) goes from -y to +y
maxAxis = absZ;
uc = x;
vc = y;
*index = 4;
}
// NEGATIVE Z
if (!isZPositive && (absZ >= absX) && (absZ >= absY)) {
// u (0 to 1) goes from +x to -x
// v (0 to 1) goes from -y to +y
maxAxis = absZ;
uc = -x;
vc = y;
*index = 5;
}
// Convert range from -1 to 1 to 0 to 1
*u = 0.5f * (uc / maxAxis + 1.0f);
*v = 0.5f * (vc / maxAxis + 1.0f);
}
//
// Simple bilinear texture filtering.
//
static void SampleTexture(float* rgba, float u, float v, int width, int height,
int channels, const float* texels) {
float sx = std::floor(u);
float sy = std::floor(v);
// Wrap mode = repeat
float uu = u - sx;
float vv = v - sy;
// clamp
uu = std::max(uu, 0.0f);
uu = std::min(uu, 1.0f);
vv = std::max(vv, 0.0f);
vv = std::min(vv, 1.0f);
float px = (width - 1) * uu;
float py = (height - 1) * vv;
int x0 = std::max(0, std::min((int)px, (width - 1)));
int y0 = std::max(0, std::min((int)py, (height - 1)));
int x1 = std::max(0, std::min((x0 + 1), (width - 1)));
int y1 = std::max(0, std::min((y0 + 1), (height - 1)));
float dx = px - (float)x0;
float dy = py - (float)y0;
float w[4];
w[0] = (1.0f - dx) * (1.0 - dy);
w[1] = (1.0f - dx) * (dy);
w[2] = (dx) * (1.0 - dy);
w[3] = (dx) * (dy);
int i00 = channels * (y0 * width + x0);
int i01 = channels * (y0 * width + x1);
int i10 = channels * (y1 * width + x0);
int i11 = channels * (y1 * width + x1);
for (int i = 0; i < channels; i++) {
rgba[i] = w[0] * texels[i00 + i] + w[1] * texels[i10 + i] +
w[2] * texels[i01 + i] + w[3] * texels[i11 + i];
}
}
static void SampleCubemap(const std::array<Image, 6>& cubemap_faces,
const float n[3], float col[3]) {
int face;
float u, v;
convert_xyz_to_cube_uv(n[0], n[1], n[2], &face, &u, &v);
v = 1.0f - v;
// std::cout << "face = " << face << std::endl;
// TODO(syoyo): Do we better consider seams on the cubemap face border?
const Image& tex = cubemap_faces[face];
// std::cout << "n = " << n[0] << ", " << n[1] << ", " << n[2] << ", uv = " <<
// u << ", " << v << std::endl;
SampleTexture(col, u, v, tex.width, tex.height, /* RGB */ 3, tex.data.data());
// col[0] = u;
// col[1] = v;
// col[2] = 0.0f;
#if 0
if (face == 0) {
col[0] = 1.0f;
col[1] = 0.0f;
col[2] = 0.0f;
} else if (face == 1) {
col[0] = 0.0f;
col[1] = 1.0f;
col[2] = 0.0f;
} else if (face == 2) {
col[0] = 0.0f;
col[1] = 0.0f;
col[2] = 1.0f;
} else if (face == 3) {
col[0] = 1.0f;
col[1] = 0.0f;
col[2] = 1.0f;
} else if (face == 4) {
col[0] = 0.0f;
col[1] = 1.0f;
col[2] = 1.0f;
} else if (face == 5) {
col[0] = 1.0f;
col[1] = 1.0f;
col[2] = 1.0f;
}
#endif
}
static void CubemapToLonglat(const std::array<Image, 6>& cubemap_faces,
const float phi_offset, /* in angle */
const int width, Image* longlat) {
int height = width / 2;
longlat->width = width;
longlat->height = height;
longlat->data.resize(size_t(width * height * 3)); // RGB
const float kPI = 3.141592f;
for (size_t y = 0; y < size_t(height); y++) {
float theta = ((y + 0.5f) / float(height)) * kPI; // [0, pi]
for (size_t x = 0; x < size_t(width); x++) {
float phi = ((x + 0.5f) / float(width)) * 2.0f * kPI; // [0, 2 pi]
phi += (phi_offset) * kPI / 180.0f;
float n[3];
// Y-up
n[0] = std::sin(theta) * std::cos(phi);
n[1] = std::cos(theta);
n[2] = -std::sin(theta) * std::sin(phi);
float col[3];
SampleCubemap(cubemap_faces, n, col);
longlat->data[3 * size_t(y * width + x) + 0] = col[0];
longlat->data[3 * size_t(y * width + x) + 1] = col[1];
longlat->data[3 * size_t(y * width + x) + 2] = col[2];
}
}
}
static unsigned char ftouc(const float f) {
int i(f * 255.0f);
i = std::max(0, std::min(255, i));
return static_cast<unsigned char>(i);
}
int main(int argc, char** argv) {
float phi_offset = 0.0f;
if (argc < 9) {
printf(
"Usage: cube2longlat px.exr nx.exr py.exr ny.exr pz.exr nz.exr "
"output_width output.exr\n");
exit(-1);
}
std::array<std::string, 6> face_filenames;
face_filenames[0] = argv[1];
face_filenames[1] = argv[2];
face_filenames[2] = argv[3];
face_filenames[3] = argv[4];
face_filenames[4] = argv[5];
face_filenames[5] = argv[6];
int output_width = atoi(argv[7]);
std::string output_filename = argv[8];
if (argc > 9) {
phi_offset = atof(argv[9]);
}
std::array<Image, 6> cubemaps;
if (!LoadCubemaps(face_filenames, &cubemaps)) {
std::cerr << "Failed to load cubemap faces." << std::endl;
return EXIT_FAILURE;
}
Image longlat;
CubemapToLonglat(cubemaps, phi_offset, output_width, &longlat);
{
std::string ext = GetFileExtension(output_filename);
if ((ext.compare("exr") == 0) || (ext.compare("EXR") == 0)) {
const char *err;
int ret = SaveEXR(longlat.data.data(), longlat.width, longlat.height,
/* RGB */ 3, /* fp16 */ 0, output_filename.c_str(), &err);
if (ret != TINYEXR_SUCCESS) {
if (err) {
std::cout << "Failed to save image as EXR. msg = " << err << ", code = " << ret << std::endl;
FreeEXRErrorMessage(err);
} else {
std::cout << "Failed to save image as EXR. code = " << ret << std::endl;
}
return EXIT_FAILURE;
}
} else if ((ext.compare("rgbm") == 0) || (ext.compare("RGBM") == 0)) {
std::vector<unsigned char> rgbm_image;
for (size_t j = 0; j < size_t(longlat.width * longlat.height); j++) {
float linear[3];
linear[0] = longlat.data[3 * j + 0];
linear[1] = longlat.data[3 * j + 1];
linear[2] = longlat.data[3 * j + 2];
float rgbm[4];
LinearToRGBM(linear, rgbm);
rgbm_image[4 * j + 0] = ftouc(rgbm[0]);
rgbm_image[4 * j + 1] = ftouc(rgbm[1]);
rgbm_image[4 * j + 2] = ftouc(rgbm[2]);
rgbm_image[4 * j + 3] = ftouc(rgbm[2]);
}
// Save as PNG.
int ret =
stbi_write_png(output_filename.c_str(), longlat.width, longlat.height,
4, rgbm_image.data(), longlat.width * 4);
if (ret == 0) {
std::cerr << "Failed to save image as RGBM file : " << output_filename
<< std::endl;
return EXIT_FAILURE;
}
} else {
if ((ext.compare("hdr") == 0) || (ext.compare("HDR") == 0)) {
// ok
} else {
std::cout << "Unknown file extension. Interpret it as RGBE format : "
<< ext << std::endl;
}
int ret = stbi_write_hdr(output_filename.c_str(), longlat.width,
longlat.height, 3, longlat.data.data());
if (ret == 0) {
std::cerr << "Failed to save image as HDR file : " << output_filename
<< std::endl;
return EXIT_FAILURE;
}
}
}
std::cout << "Write " << output_filename << std::endl;
return 0;
}