Improve LBMManager::applyLBMs() code

[dragonfireclient.git] / src / light.cpp

diff --git a/src/light.cpp b/src/light.cpp
index 575bc2c72a876c6690e5b8b7d68ba990690f0265..d5389b45060a098df3964b228e5d26ffaedbdc40 100644 (file)
--- a/src/light.cpp
+++ b/src/light.cpp
@@ -18,44 +18,76 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 */
 
 #include "light.h"
+#include <algorithm>
 #include <cmath>
 #include "util/numeric.h"
 #include "settings.h"
 
 #ifndef SERVER
 
-// Length of LIGHT_MAX+1 means LIGHT_MAX is the last value.
-// LIGHT_SUN is read as LIGHT_MAX from here.
+static u8 light_LUT[LIGHT_SUN + 1];
 
-u8 light_LUT[LIGHT_MAX+1];
-
-// the const ref to light_LUT is what is actually used in the code.
+// The const ref to light_LUT is what is actually used in the code
 const u8 *light_decode_table = light_LUT;
 
-/** Initialize or update the light value tables using the specified \p gamma.
- */
+
+struct LightingParams {
+       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 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 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
-       const float a = alpha + beta - 2;
-       const float b = 3 - 2 * alpha - beta;
-       const float c = alpha;
-// gamma correction
-       gamma = rangelim(gamma, 0.5, 3.0);
-
-       for (size_t i = 0; i < LIGHT_MAX; i++) {
-               float x = i;
-               x /= LIGHT_MAX;
-               float brightness = a * x * x * x + b * x * x + c * x;
-               brightness = powf(brightness, 1.0 / gamma);
-               light_LUT[i] = rangelim((u32)(255 * brightness), 0, 255);
-               if (i > 1 && light_LUT[i] <= light_LUT[i - 1])
-                       light_LUT[i] = light_LUT[i - 1] + 1;
+// 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;
+// 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;
+       light_LUT[LIGHT_SUN] = 255;
+
+       for (size_t i = 1; i < LIGHT_SUN; i++) {
+               float brightness = decode_light_f((float)i / LIGHT_SUN);
+               // Strictly speaking, rangelim is not necessary here—if the implementation
+               // is conforming. But we don’t want problems in any case.
+               light_LUT[i] = rangelim((s32)(255.0f * brightness), 0, 255);
+
+               // Ensure light brightens with each level
+               if (i > 0 && light_LUT[i] <= light_LUT[i - 1]) {
+                       light_LUT[i] = std::min((u8)254, light_LUT[i - 1]) + 1;
+               }
        }
-       light_LUT[LIGHT_MAX] = 255;
 }
-#endif
 
+#endif