Initial release

engine/plugins/schedulers/sgm_uniform.lua

@@ -0,0 +1,41 @@
+-- sgm_uniform.lua: SGM Uniform (Karras) — uniform in σ^(1/ρ) space
+
+scheduler = {
+    name        = "sgm_uniform",
+    display     = "SGM-Uniform (Karras)",
+    description = "Karras σ-ramp (ρ=7), front-loads structural steps",
+}
+
+function schedule(output, num_steps, shift)
+    local t_max = 0.999
+    local t_min = 0.001
+    local sigma_max = t_max / (1 - t_max)
+    local sigma_min = t_min / (1 - t_min)
+    local rho = 7.0
+
+    local inv_rho = 1.0 / rho
+    local s_max = sigma_max ^ inv_rho
+    local s_min = sigma_min ^ inv_rho
+
+    for i = 0, num_steps - 1 do
+        local frac = i / num_steps
+        local sigma = (s_max + frac * (s_min - s_max)) ^ rho
+        output[i] = sigma / (1 + sigma)
+    end
+    clamp(output, num_steps)
+    apply_shift(output, num_steps, shift)
+end
+
+function apply_shift(ts, n, shift)
+    if shift == 1.0 then return end
+    for i = 0, n - 1 do
+        local t = ts[i]; ts[i] = shift * t / (1.0 + (shift - 1.0) * t)
+    end
+end
+
+function clamp(ts, n)
+    for i = 0, n - 1 do
+        if ts[i] < 1e-6 then ts[i] = 1e-6 end
+        if ts[i] > 1.0 then ts[i] = 1.0 end
+    end
+end