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citra/src/video_core/renderer_software/sw_lighting.cpp

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// Copyright 2017 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#include <algorithm>
#include "video_core/renderer_software/sw_lighting.h"
namespace SwRenderer {
using Pica::f16;
using Pica::LightingRegs;
static float LookupLightingLut(const Pica::PicaCore::Lighting& lighting, std::size_t lut_index,
u8 index, float delta) {
ASSERT_MSG(lut_index < lighting.luts.size(), "Out of range lut");
ASSERT_MSG(index < lighting.luts[lut_index].size(), "Out of range index");
const auto& lut = lighting.luts[lut_index][index];
const float lut_value = lut.ToFloat();
const float lut_diff = lut.DiffToFloat();
return lut_value + lut_diff * delta;
}
std::pair<Common::Vec4<u8>, Common::Vec4<u8>> ComputeFragmentsColors(
const Pica::LightingRegs& lighting, const Pica::PicaCore::Lighting& lighting_state,
const Common::Quaternion<f32>& normquat, const Common::Vec3f& view,
std::span<const Common::Vec4<u8>, 4> texture_color) {
Common::Vec4f shadow;
if (lighting.config0.enable_shadow) {
shadow = texture_color[lighting.config0.shadow_selector].Cast<float>() / 255.0f;
if (lighting.config0.shadow_invert) {
shadow = Common::MakeVec(1.0f, 1.0f, 1.0f, 1.0f) - shadow;
}
} else {
shadow = Common::MakeVec(1.0f, 1.0f, 1.0f, 1.0f);
}
Common::Vec3f surface_normal{};
Common::Vec3f surface_tangent{};
if (lighting.config0.bump_mode != LightingRegs::LightingBumpMode::None) {
Common::Vec3f perturbation =
texture_color[lighting.config0.bump_selector].xyz().Cast<float>() / 127.5f -
Common::MakeVec(1.0f, 1.0f, 1.0f);
if (lighting.config0.bump_mode == LightingRegs::LightingBumpMode::NormalMap) {
if (!lighting.config0.disable_bump_renorm) {
const f32 z_square = 1 - perturbation.xy().Length2();
perturbation.z = std::sqrt(std::max(z_square, 0.0f));
}
surface_normal = perturbation;
surface_tangent = Common::MakeVec(1.0f, 0.0f, 0.0f);
} else if (lighting.config0.bump_mode == LightingRegs::LightingBumpMode::TangentMap) {
surface_normal = Common::MakeVec(0.0f, 0.0f, 1.0f);
surface_tangent = perturbation;
} else {
LOG_ERROR(HW_GPU, "Unknown bump mode {}",
static_cast<u32>(lighting.config0.bump_mode.Value()));
}
} else {
surface_normal = Common::MakeVec(0.0f, 0.0f, 1.0f);
surface_tangent = Common::MakeVec(1.0f, 0.0f, 0.0f);
}
// Use the normalized the quaternion when performing the rotation
auto normal = Common::QuaternionRotate(normquat, surface_normal);
auto tangent = Common::QuaternionRotate(normquat, surface_tangent);
Common::Vec4f diffuse_sum = {0.0f, 0.0f, 0.0f, 1.0f};
Common::Vec4f specular_sum = {0.0f, 0.0f, 0.0f, 1.0f};
for (u32 light_index = 0; light_index <= lighting.max_light_index; ++light_index) {
u32 num = lighting.light_enable.GetNum(light_index);
const auto& light_config = lighting.light[num];
const Common::Vec3f position = {f16::FromRaw(light_config.x).ToFloat32(),
f16::FromRaw(light_config.y).ToFloat32(),
f16::FromRaw(light_config.z).ToFloat32()};
Common::Vec3f refl_value{};
Common::Vec3f light_vector{};
if (light_config.config.directional) {
light_vector = position;
} else {
light_vector = position + view;
}
[[maybe_unused]] const f32 length = light_vector.Normalize();
Common::Vec3f norm_view = view.Normalized();
Common::Vec3f half_vector = norm_view + light_vector;
f32 dist_atten = 1.0f;
if (!lighting.IsDistAttenDisabled(num)) {
const f32 scale = Pica::f20::FromRaw(light_config.dist_atten_scale).ToFloat32();
const f32 bias = Pica::f20::FromRaw(light_config.dist_atten_bias).ToFloat32();
const std::size_t lut =
static_cast<std::size_t>(LightingRegs::LightingSampler::DistanceAttenuation) + num;
const f32 sample_loc = std::clamp(scale * length + bias, 0.0f, 1.0f);
const u8 lutindex =
static_cast<u8>(std::clamp(std::floor(sample_loc * 256.0f), 0.0f, 255.0f));
const f32 delta = sample_loc * 256 - lutindex;
dist_atten = LookupLightingLut(lighting_state, lut, lutindex, delta);
}
auto get_lut_value = [&](LightingRegs::LightingLutInput input, bool abs,
LightingRegs::LightingScale scale_enum,
LightingRegs::LightingSampler sampler) {
f32 result = 0.0f;
switch (input) {
case LightingRegs::LightingLutInput::NH:
result = Common::Dot(normal, half_vector.Normalized());
break;
case LightingRegs::LightingLutInput::VH:
result = Common::Dot(norm_view, half_vector.Normalized());
break;
case LightingRegs::LightingLutInput::NV:
result = Common::Dot(normal, norm_view);
break;
case LightingRegs::LightingLutInput::LN:
result = Common::Dot(light_vector, normal);
break;
case LightingRegs::LightingLutInput::SP: {
Common::Vec3<s32> spot_dir{light_config.spot_x.Value(), light_config.spot_y.Value(),
light_config.spot_z.Value()};
result = Common::Dot(light_vector, spot_dir.Cast<float>() / 2047.0f);
break;
}
case LightingRegs::LightingLutInput::CP:
if (lighting.config0.config == LightingRegs::LightingConfig::Config7) {
const Common::Vec3f norm_half_vector = half_vector.Normalized();
const Common::Vec3f half_vector_proj =
norm_half_vector - normal * Common::Dot(normal, norm_half_vector);
result = Common::Dot(half_vector_proj, tangent);
} else {
result = 0.0f;
}
break;
default:
LOG_CRITICAL(HW_GPU, "Unknown lighting LUT input {}", input);
UNIMPLEMENTED();
result = 0.0f;
}
u8 index;
f32 delta;
if (abs) {
if (light_config.config.two_sided_diffuse) {
result = std::abs(result);
} else {
result = std::max(result, 0.0f);
}
const f32 flr = std::floor(result * 256.0f);
index = static_cast<u8>(std::clamp(flr, 0.0f, 255.0f));
delta = result * 256 - index;
} else {
const f32 flr = std::floor(result * 128.0f);
const s8 signed_index = static_cast<s8>(std::clamp(flr, -128.0f, 127.0f));
delta = result * 128.0f - signed_index;
index = static_cast<u8>(signed_index);
}
const f32 scale = lighting.lut_scale.GetScale(scale_enum);
return scale * LookupLightingLut(lighting_state, static_cast<std::size_t>(sampler),
index, delta);
};
// If enabled, compute spot light attenuation value
f32 spot_atten = 1.0f;
if (!lighting.IsSpotAttenDisabled(num) &&
LightingRegs::IsLightingSamplerSupported(
lighting.config0.config, LightingRegs::LightingSampler::SpotlightAttenuation)) {
auto lut = LightingRegs::SpotlightAttenuationSampler(num);
spot_atten =
get_lut_value(lighting.lut_input.sp, lighting.abs_lut_input.disable_sp == 0,
lighting.lut_scale.sp, lut);
}
// Specular 0 component
f32 d0_lut_value = 1.0f;
if (lighting.config1.disable_lut_d0 == 0 &&
LightingRegs::IsLightingSamplerSupported(
lighting.config0.config, LightingRegs::LightingSampler::Distribution0)) {
d0_lut_value =
get_lut_value(lighting.lut_input.d0, lighting.abs_lut_input.disable_d0 == 0,
lighting.lut_scale.d0, LightingRegs::LightingSampler::Distribution0);
}
Common::Vec3f specular_0 = d0_lut_value * light_config.specular_0.ToVec3f();
// If enabled, lookup ReflectRed value, otherwise, 1.0 is used
if (lighting.config1.disable_lut_rr == 0 &&
LightingRegs::IsLightingSamplerSupported(lighting.config0.config,
LightingRegs::LightingSampler::ReflectRed)) {
refl_value.x =
get_lut_value(lighting.lut_input.rr, lighting.abs_lut_input.disable_rr == 0,
lighting.lut_scale.rr, LightingRegs::LightingSampler::ReflectRed);
} else {
refl_value.x = 1.0f;
}
// If enabled, lookup ReflectGreen value, otherwise, ReflectRed value is used
if (lighting.config1.disable_lut_rg == 0 &&
LightingRegs::IsLightingSamplerSupported(lighting.config0.config,
LightingRegs::LightingSampler::ReflectGreen)) {
refl_value.y =
get_lut_value(lighting.lut_input.rg, lighting.abs_lut_input.disable_rg == 0,
lighting.lut_scale.rg, LightingRegs::LightingSampler::ReflectGreen);
} else {
refl_value.y = refl_value.x;
}
// If enabled, lookup ReflectBlue value, otherwise, ReflectRed value is used
if (lighting.config1.disable_lut_rb == 0 &&
LightingRegs::IsLightingSamplerSupported(lighting.config0.config,
LightingRegs::LightingSampler::ReflectBlue)) {
refl_value.z =
get_lut_value(lighting.lut_input.rb, lighting.abs_lut_input.disable_rb == 0,
lighting.lut_scale.rb, LightingRegs::LightingSampler::ReflectBlue);
} else {
refl_value.z = refl_value.x;
}
// Specular 1 component
f32 d1_lut_value = 1.0f;
if (lighting.config1.disable_lut_d1 == 0 &&
LightingRegs::IsLightingSamplerSupported(
lighting.config0.config, LightingRegs::LightingSampler::Distribution1)) {
d1_lut_value =
get_lut_value(lighting.lut_input.d1, lighting.abs_lut_input.disable_d1 == 0,
lighting.lut_scale.d1, LightingRegs::LightingSampler::Distribution1);
}
Common::Vec3f specular_1 = d1_lut_value * refl_value * light_config.specular_1.ToVec3f();
// Fresnel
// Note: only the last entry in the light slots applies the Fresnel factor
if (light_index == lighting.max_light_index && lighting.config1.disable_lut_fr == 0 &&
LightingRegs::IsLightingSamplerSupported(lighting.config0.config,
LightingRegs::LightingSampler::Fresnel)) {
const f32 lut_value =
get_lut_value(lighting.lut_input.fr, lighting.abs_lut_input.disable_fr == 0,
lighting.lut_scale.fr, LightingRegs::LightingSampler::Fresnel);
// Enabled for diffuse lighting alpha component
if (lighting.config0.enable_primary_alpha) {
diffuse_sum.a() = lut_value;
}
// Enabled for the specular lighting alpha component
if (lighting.config0.enable_secondary_alpha) {
specular_sum.a() = lut_value;
}
}
auto dot_product = Common::Dot(light_vector, normal);
if (light_config.config.two_sided_diffuse) {
dot_product = std::abs(dot_product);
} else {
dot_product = std::max(dot_product, 0.0f);
}
f32 clamp_highlights = 1.0f;
if (lighting.config0.clamp_highlights) {
clamp_highlights = dot_product == 0.0f ? 0.0f : 1.0f;
}
if (light_config.config.geometric_factor_0 || light_config.config.geometric_factor_1) {
f32 geo_factor = half_vector.Length2();
geo_factor = geo_factor == 0.0f ? 0.0f : std::min(dot_product / geo_factor, 1.0f);
if (light_config.config.geometric_factor_0) {
specular_0 *= geo_factor;
}
if (light_config.config.geometric_factor_1) {
specular_1 *= geo_factor;
}
}
const bool shadow_primary_enable =
lighting.config0.shadow_primary && !lighting.IsShadowDisabled(num);
const bool shadow_secondary_enable =
lighting.config0.shadow_secondary && !lighting.IsShadowDisabled(num);
const auto shadow_primary =
shadow_primary_enable ? shadow.xyz() : Common::MakeVec(1.f, 1.f, 1.f);
const auto shadow_secondary =
shadow_secondary_enable ? shadow.xyz() : Common::MakeVec(1.f, 1.f, 1.f);
const auto diffuse = (light_config.diffuse.ToVec3f() * dot_product * shadow_primary +
light_config.ambient.ToVec3f()) *
dist_atten * spot_atten;
const auto specular = (specular_0 + specular_1) * clamp_highlights * dist_atten *
spot_atten * shadow_secondary;
diffuse_sum += Common::MakeVec(diffuse, 0.0f);
specular_sum += Common::MakeVec(specular, 0.0f);
}
if (lighting.config0.shadow_alpha) {
// Alpha shadow also uses the Fresnel selecotr to determine which alpha to apply
// Enabled for diffuse lighting alpha component
if (lighting.config0.enable_primary_alpha) {
diffuse_sum.a() *= shadow.w;
}
// Enabled for the specular lighting alpha component
if (lighting.config0.enable_secondary_alpha) {
specular_sum.a() *= shadow.w;
}
}
diffuse_sum += Common::MakeVec(lighting.global_ambient.ToVec3f(), 0.0f);
const auto diffuse = Common::MakeVec(std::clamp(diffuse_sum.x, 0.0f, 1.0f) * 255,
std::clamp(diffuse_sum.y, 0.0f, 1.0f) * 255,
std::clamp(diffuse_sum.z, 0.0f, 1.0f) * 255,
std::clamp(diffuse_sum.w, 0.0f, 1.0f) * 255)
.Cast<u8>();
const auto specular = Common::MakeVec(std::clamp(specular_sum.x, 0.0f, 1.0f) * 255,
std::clamp(specular_sum.y, 0.0f, 1.0f) * 255,
std::clamp(specular_sum.z, 0.0f, 1.0f) * 255,
std::clamp(specular_sum.w, 0.0f, 1.0f) * 255)
.Cast<u8>();
return std::make_pair(diffuse, specular);
}
} // namespace SwRenderer
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