ParticleSpawner: Fix crash when attaching to invisible entity

[oweals/minetest.git] / src / light.cpp

diff --git a/src/light.cpp b/src/light.cpp
index c60f8eacaaa47ea99c7a5dd7007baa909de0f1d4..8196fedffcc820fa58d317f10b364dd2e29da27e 100644 (file)
--- a/src/light.cpp
+++ b/src/light.cpp
@@ -29,44 +29,48 @@ static u8 light_LUT[LIGHT_SUN + 1];
 // The const ref to light_LUT is what is actually used in the code
 const u8 *light_decode_table = light_LUT;
 
+
 struct LightingParams {
-       float a, b, c; // polynomial coefficients
-       float boost, center, sigma; // normal boost parameters
-       float gamma;
+       float a, b, c; // Lighting curve polynomial coefficients
+       float boost, center, sigma; // Lighting curve parametric boost
+       float gamma; // Lighting curve gamma correction
 };
 
 static LightingParams params;
 
+
 float decode_light_f(float x)
 {
-       if (x >= 1.0f) // x is equal to 1.0f half the time
+       if (x >= 1.0f) // x is often 1.0f
                return 1.0f;
        x = std::fmax(x, 0.0f);
        float brightness = ((params.a * x + params.b) * x + params.c) * x;
-       brightness += params.boost * std::exp(-0.5f * sqr((x - params.center) / params.sigma));
-       if (brightness <= 0.0f) // may happen if parameters are insane
+       brightness += params.boost *
+               std::exp(-0.5f * sqr((x - params.center) / params.sigma));
+       if (brightness <= 0.0f) // May happen if parameters are extreme
                return 0.0f;
        if (brightness >= 1.0f)
                return 1.0f;
        return powf(brightness, 1.0f / params.gamma);
 }
 
+
 // Initialize or update the light value tables using the specified gamma
 void set_light_table(float gamma)
 {
-// Lighting curve derivatives
-       const float alpha = g_settings->getFloat("lighting_alpha");
-       const float beta  = g_settings->getFloat("lighting_beta");
-// Lighting curve coefficients
+// Lighting curve bounding gradients
+       const float alpha = rangelim(g_settings->getFloat("lighting_alpha"), 0.0f, 3.0f);
+       const float beta  = rangelim(g_settings->getFloat("lighting_beta"), 0.0f, 3.0f);
+// Lighting curve polynomial coefficients
        params.a = alpha + beta - 2.0f;
        params.b = 3.0f - 2.0f * alpha - beta;
        params.c = alpha;
-// Mid boost
-       params.boost = g_settings->getFloat("lighting_boost");
-       params.center = g_settings->getFloat("lighting_boost_center");
-       params.sigma = g_settings->getFloat("lighting_boost_spread");
-// Gamma correction
-       params.gamma = rangelim(gamma, 0.5f, 3.0f);
+// Lighting curve parametric boost
+       params.boost = rangelim(g_settings->getFloat("lighting_boost"), 0.0f, 0.4f);
+       params.center = rangelim(g_settings->getFloat("lighting_boost_center"), 0.0f, 1.0f);
+       params.sigma = rangelim(g_settings->getFloat("lighting_boost_spread"), 0.0f, 0.4f);
+// Lighting curve gamma correction
+       params.gamma = rangelim(gamma, 0.33f, 3.0f);
 
 // Boundary values should be fixed
        light_LUT[0] = 0;