PbrMaterial.cpp

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#include "procgen/texture/PbrMaterial.h"
#include "procgen/texture/ColorRamp.h"
#include "procgen/texture/NoiseField.h"
 
#include "image/ImageData.h"
 
#include <algorithm>
#include <cmath>
 
namespace eve::procgen {
 
PbrRecipeRegistry &PbrRecipeRegistry::instance() {
    static PbrRecipeRegistry reg;
    return reg;
}
 
void PbrRecipeRegistry::registerPbrRecipe(const std::string &id, PbrRecipeFn fn) {
    recipes_[id] = std::move(fn);
}
 
bool PbrRecipeRegistry::has(const std::string &id) const {
    return recipes_.find(id) != recipes_.end();
}
 
PbrTextureSet *PbrRecipeRegistry::generate(const std::string &id, const Params &params,
                                           std::string &error) const {
    auto it = recipes_.find(id);
    if (it == recipes_.end()) {
        error = "unknown pbr recipe: " + id;
        return nullptr;
    }
    return it->second(params, error);
}
 
std::vector<std::string> PbrRecipeRegistry::list() const {
    std::vector<std::string> ids;
    ids.reserve(recipes_.size());
    for (const auto &kv : recipes_) ids.push_back(kv.first);
    std::sort(ids.begin(), ids.end());
    return ids;
}
 
void PbrRecipeRegistry::registerPbrBuiltins() {
    if (builtinsRegistered_) return;
    for (const TextureRecipeDef &def : builtinTextureDefs()) {
        const std::string id = "pbr." + def.id.substr(def.id.find('.') + 1);
        registerPbrRecipe(id, [def](const Params &params, std::string &error) {
            return generatePbrSet(def, params, error);
        });
    }
    builtinsRegistered_ = true;
}
 
image::ImageData *grayscaleImage(const std::vector<float> &values, int w, int h) {
    auto *img    = new image::ImageData(w, h, "RGBA8");
    auto *pixels = static_cast<uint8_t *>(img->getData());
    for (int i = 0; i < w * h && i < int(values.size()); ++i) {
        const uint8_t v = uint8_t(std::lround(std::clamp(values[size_t(i)], 0.f, 1.f) * 255.f));
        const size_t  o = size_t(i) * 4u;
        pixels[o + 0] = pixels[o + 1] = pixels[o + 2] = v;
        pixels[o + 3]                                  = 255;
    }
    return img;
}
 
PbrTextureSet *generatePbrSet(const TextureRecipeDef &def, const Params &params,
                              std::string &error) {
    const auto ctx = TextureGenContext::fromParams(params);
    if (ctx.width > 4096 || ctx.height > 4096) {
        error = "texture size too large (max 4096)";
        return nullptr;
    }
 
    // Recipe defaults, then per-call overrides.
    PbrParams pbr = def.pbr;
    pbr.roughnessLow   = std::clamp(params.getFloat("roughnessLow", pbr.roughnessLow), 0.f, 1.f);
    pbr.roughnessHigh  = std::clamp(params.getFloat("roughnessHigh", pbr.roughnessHigh), 0.f, 1.f);
    pbr.metallic       = std::clamp(params.getFloat("metallic", pbr.metallic), 0.f, 1.f);
    pbr.normalStrength = std::max(0.01f, params.getFloat("normalStrength", pbr.normalStrength));
    pbr.aoStrength     = std::clamp(params.getFloat("aoStrength", pbr.aoStrength), 0.f, 5.f);
    pbr.heightStrength = std::max(0.f, params.getFloat("heightStrength", pbr.heightStrength));
 
    std::vector<float> height;
    fillHeightField(ctx, def.height, height);
    const int w = ctx.width;
    const int h = ctx.height;
 
    auto *set = new PbrTextureSet();
    set->albedo = new image::ImageData(w, h, "RGBA8");
    paintHeightToImage(*set->albedo, height, w, h, def.albedo, ctx.colors, ctx.pixelSize);
    set->normal = heightToNormalImage(height, w, h, pbr.normalStrength, ctx.seamless);
 
    std::vector<float> rough(size_t(w * h));
    std::vector<float> heightMap(size_t(w * h));
    std::vector<float> ao(size_t(w * h));
    const int r = std::max(1, std::min(w, h) / 64);  // cavity sampling radius
    for (int y = 0; y < h; ++y) {
        for (int x = 0; x < w; ++x) {
            const size_t i = size_t(y) * size_t(w) + size_t(x);
            const float  hh = height[i];
            rough[size_t(i)] =
                pbr.roughnessLow + (pbr.roughnessHigh - pbr.roughnessLow) * hh;
            heightMap[i] = std::clamp(0.5f + (hh - 0.5f) * pbr.heightStrength, 0.f, 1.f);
 
            // Cavity AO: darker where a pixel sits below its neighbourhood mean.
            float sum = 0.f;
            int   cnt = 0;
            for (int dy = -r; dy <= r; ++dy) {
                for (int dx = -r; dx <= r; ++dx) {
                    int xx = x + dx, yy = y + dy;
                    if (ctx.seamless) {
                        xx = ((xx % w) + w) % w;
                        yy = ((yy % h) + h) % h;
                    } else {
                        if (xx < 0 || yy < 0 || xx >= w || yy >= h) continue;
                    }
                    sum += height[size_t(yy) * size_t(w) + size_t(xx)];
                    ++cnt;
                }
            }
            const float local = cnt > 0 ? sum / float(cnt) : hh;
            ao[i] = std::clamp(1.f - pbr.aoStrength * std::max(0.f, local - hh), 0.f, 1.f);
        }
    }
    set->roughness = grayscaleImage(rough, w, h);
    set->metallic  = grayscaleImage(std::vector<float>(size_t(w * h), pbr.metallic), w, h);
    set->height    = grayscaleImage(heightMap, w, h);
    set->ao        = grayscaleImage(ao, w, h);
    return set;
}
 
}  // namespace eve::procgen