Add more visual feedback for button states (#8916)

[dragonfireclient.git] / src / light.cpp

diff --git a/src/light.cpp b/src/light.cpp
index 4a20c58ab697fac01af1841d3c10fc6e1530538f..9b6f5c210ee7df4da84ff2208328a3b165eafe89 100644 (file)
--- a/src/light.cpp
+++ b/src/light.cpp
@@ -24,13 +24,33 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #ifndef SERVER
 
-// Length of LIGHT_MAX + 1 means LIGHT_MAX is the last value.
-// LIGHT_SUN is read as LIGHT_MAX from here.
-u8 light_LUT[LIGHT_MAX + 1];
+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;
+};
+
+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);
+}
+
 // Initialize or update the light value tables using the specified gamma
 void set_light_table(float gamma)
 {
@@ -38,26 +58,29 @@ void set_light_table(float gamma)
        const float alpha = g_settings->getFloat("lighting_alpha");
        const float beta  = g_settings->getFloat("lighting_beta");
 // Lighting curve coefficients
-       const float a = alpha + beta - 2.0f;
-       const float b = 3.0f - 2.0f * alpha - beta;
-       const float c = alpha;
+       params.a = alpha + beta - 2.0f;
+       params.b = 3.0f - 2.0f * alpha - beta;
+       params.c = alpha;
 // Mid boost
-       const float d = g_settings->getFloat("lighting_boost");
-       const float e = g_settings->getFloat("lighting_boost_center");
-       const float f = g_settings->getFloat("lighting_boost_spread");
+       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
-       gamma = rangelim(gamma, 0.5f, 3.0f);
-
-       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;
-               float boost = d * std::exp(-((x - e) * (x - e)) / (2.0f * f * f));
-               brightness = powf(brightness + boost, 1.0f / gamma);
-               light_LUT[i] = rangelim((u32)(255.0f * brightness), 0, 255);
+       params.gamma = rangelim(gamma, 0.5f, 10.0f);
+
+// 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 > 1 && light_LUT[i] <= light_LUT[i - 1])
                        light_LUT[i] = light_LUT[i - 1] + 1;
        }
-       light_LUT[LIGHT_MAX] = 255;
 }
+
 #endif