*/
#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.
- */
+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)
{
-// lighting curve derivatives
+// 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);
+// 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);
+
+// 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
+#endif