121 lines
3.6 KiB
C++
121 lines
3.6 KiB
C++
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#include <iostream>
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#include <vector>
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#include <algorithm>
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#include <cmath>
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#include <sstream>
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#include <fstream>
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#include "vec.h"
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#define STB_IMAGE_WRITE_IMPLEMENTATION
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#include "stb_image_write.h"
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#define STB_IMAGE_IMPLEMENTATION
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#include "stb_image.h"
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int resolution = 128;
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int channel = 3;
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Vec2f Hammersley(uint32_t i, uint32_t N) {
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uint32_t bits = (i << 16u) | (i >> 16u);
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bits = ((bits & 0x55555555u) << 1u) | ((bits & 0xAAAAAAAAu) >> 1u);
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bits = ((bits & 0x33333333u) << 2u) | ((bits & 0xCCCCCCCCu) >> 2u);
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bits = ((bits & 0x0F0F0F0Fu) << 4u) | ((bits & 0xF0F0F0F0u) >> 4u);
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bits = ((bits & 0x00FF00FFu) << 8u) | ((bits & 0xFF00FF00u) >> 8u);
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float rdi = float(bits) * 2.3283064365386963e-10;
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return {float(i) / float(N), rdi};
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}
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Vec3f ImportanceSampleGGX(Vec2f Xi, Vec3f N, float roughness) {
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float a = roughness * roughness;
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// TODO: Copy the code from your previous work - Bonus 1
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return Vec3f(1.0f);
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}
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Vec3f IntegrateEmu(Vec3f V, float roughness, float NdotV, Vec3f Ei) {
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Vec3f Eavg = Vec3f(0.0f);
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const int sample_count = 1024;
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Vec3f N = Vec3f(0.0, 0.0, 1.0);
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for (int i = 0; i < sample_count; i++)
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{
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Vec2f Xi = Hammersley(i, sample_count);
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Vec3f H = ImportanceSampleGGX(Xi, N, roughness);
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Vec3f L = normalize(H * 2.0f * dot(V, H) - V);
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float NoL = std::max(L.z, 0.0f);
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float NoH = std::max(H.z, 0.0f);
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float VoH = std::max(dot(V, H), 0.0f);
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float NoV = std::max(dot(N, V), 0.0f);
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// TODO: To calculate Eavg here - Bonus 1
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}
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return Vec3f(1.0);
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}
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void setRGB(int x, int y, float alpha, unsigned char *data) {
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data[3 * (resolution * x + y) + 0] = uint8_t(alpha);
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data[3 * (resolution * x + y) + 1] = uint8_t(alpha);
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data[3 * (resolution * x + y) + 2] = uint8_t(alpha);
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}
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void setRGB(int x, int y, Vec3f alpha, unsigned char *data) {
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data[3 * (resolution * x + y) + 0] = uint8_t(alpha.x);
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data[3 * (resolution * x + y) + 1] = uint8_t(alpha.y);
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data[3 * (resolution * x + y) + 2] = uint8_t(alpha.z);
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}
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Vec3f getEmu(int x, int y, int alpha, unsigned char *data, float NdotV, float roughness) {
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return Vec3f(data[3 * (resolution * x + y) + 0],
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data[3 * (resolution * x + y) + 1],
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data[3 * (resolution * x + y) + 2]);
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}
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int main() {
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unsigned char *Edata = stbi_load("./GGX_E_LUT.png", &resolution, &resolution, &channel, 3);
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if (Edata == NULL)
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{
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std::cout << "ERROE_FILE_NOT_LOAD" << std::endl;
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return -1;
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}
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else
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{
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std::cout << resolution << " " << resolution << " " << channel << std::endl;
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// | -----> mu(j)
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// |
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// | rough（i）
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// Flip it, if you want the data written to the texture
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uint8_t data[resolution * resolution * 3];
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float step = 1.0 / resolution;
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Vec3f Eavg = Vec3f(0.0);
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for (int i = 0; i < resolution; i++)
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{
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float roughness = step * (static_cast<float>(i) + 0.5f);
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for (int j = 0; j < resolution; j++)
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{
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float NdotV = step * (static_cast<float>(j) + 0.5f);
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Vec3f V = Vec3f(std::sqrt(1.f - NdotV * NdotV), 0.f, NdotV);
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Vec3f Ei = getEmu((resolution - 1 - i), j, 0, Edata, NdotV, roughness);
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Eavg += IntegrateEmu(V, roughness, NdotV, Ei) * step;
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setRGB(i, j, 0.0, data);
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}
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for(int k = 0; k < resolution; k++)
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{
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setRGB(i, k, Eavg, data);
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}
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Eavg = Vec3f(0.0);
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}
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stbi_flip_vertically_on_write(true);
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stbi_write_png("GGX_Eavg_LUT.png", resolution, resolution, channel, data, 0);
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}
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stbi_image_free(Edata);
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return 0;
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}
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