Rename guiScrollBar to GUIScrollBar

[dragonfireclient.git] / src / light.cpp

diff --git a/src/light.cpp b/src/light.cpp
index 4a3ca5a60767c8388429f59e0a025935f80e7375..9b6f5c210ee7df4da84ff2208328a3b165eafe89 100644 (file)
--- a/src/light.cpp
+++ b/src/light.cpp
@@ -18,68 +18,69 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 */
 
 #include "light.h"
-#include <math.h>
+#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.
- *  If \p gamma == 1.0 then the light table is linear.  Typically values for
- *  gamma range between 1.8 and 2.2.
- *
- *  @note The value for gamma will be restricted to the range 1.1 <= gamma <= 3.0.
- *
- *  @note This function is not, currently, a simple linear to gamma encoding
- *        because adjustments are made so that a gamma of 1.8 gives the same
- *        results as those hardcoded for use by the server.
- */
-void set_light_table(float gamma)
-{
-       static const float brightness_step = 255.0f / (LIGHT_MAX + 1);
+struct LightingParams {
+       float a, b, c; // polynomial coefficients
+       float boost, center, sigma; // normal boost parameters
+       float gamma;
+};
 
-       // this table is pure arbitrary values, made so that
-       // at gamma 2.2 the game looks not too dark at light=1,
-       // and mostly linear for the rest of the scale.
-       // we could try to inverse the gamma power function, but this
-       // is simpler and quicker.
-       static const int adjustments[LIGHT_MAX + 1] = {
-               -67,
-               -91,
-               -125,
-               -115,
-               -104,
-               -85,
-               -70,
-               -63,
-               -56,
-               -49,
-               -42,
-               -35,
-               -28,
-               -22,
-               0
-       };
+static LightingParams params;
+
+float decode_light_f(float x)
+{
+       if (x >= 1.0f) // x is equal to 1.0f half the time
+               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
+               return 0.0f;
+       if (brightness >= 1.0f)
+               return 1.0f;
+       return powf(brightness, 1.0f / params.gamma);
+}
 
-       gamma = rangelim(gamma, 1.0, 3.0);
+// 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
+       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, 10.0f);
 
-       float brightness = brightness_step;
+// Boundary values should be fixed
+       light_LUT[0] = 0;
+       light_LUT[LIGHT_SUN] = 255;
 
-       for (size_t i = 0; i < LIGHT_MAX; i++) {
-               light_LUT[i] = (u8)(255 * powf(brightness / 255.0f, 1.0 / gamma));
-               light_LUT[i] = rangelim(light_LUT[i] + adjustments[i], 0, 255);
-               if (i > 1 && light_LUT[i] < light_LUT[i - 1])
+       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 > 1 && light_LUT[i] <= light_LUT[i - 1])
                        light_LUT[i] = light_LUT[i - 1] + 1;
-               brightness += brightness_step;
        }
-       light_LUT[LIGHT_MAX] = 255;
 }
-#endif
 
+#endif