feat: add MiniMax-H3-Image support (#2324)

src/runtime/denoiser.hpp

@@ -2,6 +2,7 @@
 #define __SD_RUNTIME_DENOISER_HPP__
 
 #include <algorithm>
+#include <array>
 #include <cctype>
 #include <cmath>
 #include <cstring>
@@ -1405,6 +1406,38 @@ struct MingImageFlowDenoiser : DiscreteFlowDenoiser {
     }
 };
 
+struct MiniMaxH3ImageDenoiser : public DiscreteFlowDenoiser {
+    std::array<float, 7> pdd_sigmas;
+
+    explicit MiniMaxH3ImageDenoiser(const std::array<float, 7>& pdd_sigmas)
+        : DiscreteFlowDenoiser(1.f), pdd_sigmas(pdd_sigmas) {}
+
+    float sigma_min() override { return 0.f; }
+    float sigma_max() override { return 1.f; }
+
+    float t_to_sigma(float t) override {
+        const float position = (1.f - std::clamp(t / (TIMESTEPS - 1.f), 0.f, 1.f)) * 6.f;
+        const size_t index   = std::min<size_t>(static_cast<size_t>(position), 5);
+        const auto& grid     = pdd_sigmas;
+        return grid[index] + (position - index) * (grid[index + 1] - grid[index]);
+    }
+
+    std::vector<float> get_sigmas(uint32_t n, int image_seq_len, scheduler_t scheduler, SDVersion version, const char* extra_sample_args = nullptr) override {
+        if (scheduler != DISCRETE_SCHEDULER) {
+            return DiscreteFlowDenoiser::get_sigmas(n, image_seq_len, scheduler, version, extra_sample_args);
+        }
+        if (n == 0) {
+            return {};
+        }
+        std::vector<float> sigmas;
+        sigmas.reserve(n + 1);
+        for (uint32_t i = 0; i <= n; ++i) {
+            sigmas.push_back(t_to_sigma((1.f - static_cast<float>(i) / n) * (TIMESTEPS - 1.f)));
+        }
+        return sigmas;
+    }
+};
+
 struct H3AVFlowDenoiser : public DiscreteFlowDenoiser {
     int64_t video_channels;
     float audio_shift;