diff options
| -rw-r--r-- | builtin/settingtypes.txt | 39 | ||||
| -rw-r--r-- | src/light.cpp | 36 |
2 files changed, 44 insertions, 31 deletions
diff --git a/builtin/settingtypes.txt b/builtin/settingtypes.txt index fa6591c2f..feb29c2e2 100644 --- a/builtin/settingtypes.txt +++ b/builtin/settingtypes.txt @@ -639,25 +639,34 @@ vsync (VSync) bool false # Field of view in degrees. fov (Field of view) int 72 45 160 -# Adjust the gamma encoding for the light tables. Higher numbers are brighter. -# This setting is for the client only and is ignored by the server. -display_gamma (Gamma) float 1.0 0.5 10.0 +# Alters the light curve by applying 'gamma correction' to it. +# Higher values make middle and lower light levels brighter. +# Value '1.0' leaves the light curve unaltered. +# This only has significant effect on daylight and artificial +# light, it has very little effect on natural night light. +display_gamma (Light curve gamma) float 1.0 0.33 3.0 # Gradient of light curve at minimum light level. -lighting_alpha (Darkness sharpness) float 0.0 0.0 4.0 +# Controls the contrast of the lowest light levels. +lighting_alpha (Light curve low gradient) float 0.0 0.0 3.0 # Gradient of light curve at maximum light level. -lighting_beta (Lightness sharpness) float 1.5 0.0 4.0 - -# Strength of light curve mid-boost. -lighting_boost (Light curve mid boost) float 0.2 0.0 1.0 - -# Center of light curve mid-boost. -lighting_boost_center (Light curve mid boost center) float 0.5 0.0 1.0 - -# Spread of light curve mid-boost. -# Standard deviation of the mid-boost Gaussian. -lighting_boost_spread (Light curve mid boost spread) float 0.2 0.0 1.0 +# Controls the contrast of the highest light levels. +lighting_beta (Light curve high gradient) float 1.5 0.0 3.0 + +# Strength of light curve boost. +# The 3 'boost' parameters define a range of the light +# curve that is boosted in brightness. +lighting_boost (Light curve boost) float 0.2 0.0 0.4 + +# Center of light curve boost range. +# Where 0.0 is minimum light level, 1.0 is maximum light level. +lighting_boost_center (Light curve boost center) float 0.5 0.0 1.0 + +# Spread of light curve boost range. +# Controls the width of the range to be boosted. +# Standard deviation of the light curve boost Gaussian. +lighting_boost_spread (Light curve boost spread) float 0.2 0.0 0.4 # Path to texture directory. All textures are first searched from here. texture_path (Texture path) path diff --git a/src/light.cpp b/src/light.cpp index 9b6f5c210..8196fedff 100644 --- 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, 10.0f); +// 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; |