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Backport DirectionalLight fade_start property to 3.x
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- Implement shadow fading when using the Orthogonal shadow mode
  (like in `master`).

This allows customizing the distance at which directional shadows
start to fade away. Shadow fading will also always start at the same
distance now, regardless of the current shadow mode in use.

This is useful for enclosed levels to prevent shadows from fading
at all with a well-tuned maximum distance.

The default fade start value (0.8) results in fading happening later
in the distance compared to the previous behavior, where fading started
from the last shadow split distance (0.6 in PSSM 4 Splits and
0.1 in PSSM 2 Splits).
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Calinou committed Nov 20, 2023
1 parent e96c42f commit 4fefb13
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Showing 14 changed files with 53 additions and 19 deletions.
3 changes: 3 additions & 0 deletions doc/classes/DirectionalLight.xml
Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,9 @@
<member name="directional_shadow_depth_range" type="int" setter="set_shadow_depth_range" getter="get_shadow_depth_range" enum="DirectionalLight.ShadowDepthRange" default="0">
Optimizes shadow rendering for detail versus movement. See [enum ShadowDepthRange].
</member>
<member name="directional_shadow_fade_start" type="float" setter="set_param" getter="get_param" default="0.8">
Proportion of [member directional_shadow_max_distance] at which point the shadow starts to fade. At [member directional_shadow_max_distance], the shadow will disappear. The default value is a balance between smooth fading and distant shadow visibility. If the camera moves fast and the [member directional_shadow_max_distance] is low, consider lowering [member directional_shadow_fade_start] below [code]0.8[/code] to make shadow transitions less noticeable. On the other hand, if you tuned [member directional_shadow_max_distance] to cover the entire scene, you can set [member directional_shadow_fade_start] to [code]1.0[/code] to prevent the shadow from fading in the distance (it will suddenly cut off instead).
</member>
<member name="directional_shadow_max_distance" type="float" setter="set_param" getter="get_param" default="100.0">
The maximum distance for shadow splits. Increasing this value will make directional shadows visible from further away, at the cost of lower overall shadow detail and performance (since more objects need to be included in the directional shadow rendering).
</member>
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5 changes: 4 additions & 1 deletion doc/classes/Light.xml
Original file line number Diff line number Diff line change
Expand Up @@ -122,7 +122,10 @@
<constant name="PARAM_SHADOW_BIAS_SPLIT_SCALE" value="15" enum="Param">
Constant for accessing [member DirectionalLight.directional_shadow_bias_split_scale].
</constant>
<constant name="PARAM_MAX" value="16" enum="Param">
<constant name="PARAM_SHADOW_FADE_START" value="16" enum="Param">
Constant for accessing [member DirectionalLight.directional_shadow_fade_start].
</constant>
<constant name="PARAM_MAX" value="17" enum="Param">
Represents the size of the [enum Param] enum.
</constant>
<constant name="BAKE_DISABLED" value="0" enum="BakeMode">
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5 changes: 4 additions & 1 deletion doc/classes/VisualServer.xml
Original file line number Diff line number Diff line change
Expand Up @@ -3648,7 +3648,10 @@
<constant name="LIGHT_PARAM_SHADOW_BIAS_SPLIT_SCALE" value="15" enum="LightParam">
Increases bias on further splits to fix self-shadowing that only occurs far away from the camera.
</constant>
<constant name="LIGHT_PARAM_MAX" value="16" enum="LightParam">
<constant name="LIGHT_PARAM_SHADOW_FADE_START" value="16" enum="LightParam">
Proportion of [constant LIGHT_PARAM_SHADOW_MAX_DISTANCE] at which point the shadow starts to fade. At [constant LIGHT_PARAM_SHADOW_MAX_DISTANCE], the shadow will disappear. The default value is a balance between smooth fading and distant shadow visibility. If the camera moves fast and the [constant LIGHT_PARAM_SHADOW_MAX_DISTANCE] is low, consider lowering [constant LIGHT_PARAM_SHADOW_FADE_START] below [code]0.8[/code] to make shadow transitions less noticeable. On the other hand, if you tuned [constant LIGHT_PARAM_SHADOW_MAX_DISTANCE] to cover the entire scene, you can set [constant LIGHT_PARAM_SHADOW_FADE_START] to [code]1.0[/code] to prevent the shadow from fading in the distance (it will suddenly cut off instead).
</constant>
<constant name="LIGHT_PARAM_MAX" value="17" enum="LightParam">
Represents the size of the [enum LightParam] enum.
</constant>
<constant name="LIGHT_BAKE_DISABLED" value="0" enum="LightBakeMode">
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6 changes: 6 additions & 0 deletions drivers/gles2/rasterizer_scene_gles2.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -2087,6 +2087,12 @@ void RasterizerSceneGLES2::_setup_light(LightInstance *light, ShadowAtlas *shado
// state.scene_shader.set_uniform(SceneShaderGLES2::LIGHT_CLAMP, light_clamp);
state.scene_shader.set_uniform(SceneShaderGLES2::SHADOW_PIXEL_SIZE, Size2(1.0 / directional_shadow.size, 1.0 / directional_shadow.size));
state.scene_shader.set_uniform(SceneShaderGLES2::LIGHT_SPLIT_OFFSETS, split_offsets);

const float fade_start = light_ptr->param[VS::LIGHT_PARAM_SHADOW_FADE_START];
// Using 1.0 would break `smoothstep()` in the shader.
state.scene_shader.set_uniform(SceneShaderGLES2::FADE_FROM, -split_offsets[shadow_count - 1] * MIN(fade_start, 0.999));
state.scene_shader.set_uniform(SceneShaderGLES2::FADE_TO, -split_offsets[shadow_count - 1]);

state.scene_shader.set_uniform(SceneShaderGLES2::LIGHT_SHADOW_MATRIX, matrices[0]);
state.scene_shader.set_uniform(SceneShaderGLES2::LIGHT_SHADOW_MATRIX2, matrices[1]);
state.scene_shader.set_uniform(SceneShaderGLES2::LIGHT_SHADOW_MATRIX3, matrices[2]);
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4 changes: 3 additions & 1 deletion drivers/gles2/rasterizer_storage_gles2.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -4233,6 +4233,7 @@ RID RasterizerStorageGLES2::light_create(VS::LightType p_type) {
light->param[VS::LIGHT_PARAM_SHADOW_SPLIT_3_OFFSET] = 0.6;
light->param[VS::LIGHT_PARAM_SHADOW_NORMAL_BIAS] = 0.1;
light->param[VS::LIGHT_PARAM_SHADOW_BIAS_SPLIT_SCALE] = 0.1;
light->param[VS::LIGHT_PARAM_SHADOW_FADE_START] = 0.8;

light->color = Color(1, 1, 1, 1);
light->shadow = false;
Expand Down Expand Up @@ -4270,7 +4271,8 @@ void RasterizerStorageGLES2::light_set_param(RID p_light, VS::LightParam p_param
case VS::LIGHT_PARAM_SHADOW_SPLIT_2_OFFSET:
case VS::LIGHT_PARAM_SHADOW_SPLIT_3_OFFSET:
case VS::LIGHT_PARAM_SHADOW_NORMAL_BIAS:
case VS::LIGHT_PARAM_SHADOW_BIAS: {
case VS::LIGHT_PARAM_SHADOW_BIAS:
case VS::LIGHT_PARAM_SHADOW_FADE_START: {
light->version++;
light->instance_change_notify(true, false);
} break;
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15 changes: 4 additions & 11 deletions drivers/gles2/shaders/scene.glsl
Original file line number Diff line number Diff line change
Expand Up @@ -1104,6 +1104,8 @@ uniform highp sampler2D light_shadow_atlas; //texunit:-3
#ifdef LIGHT_MODE_DIRECTIONAL
uniform highp sampler2D light_directional_shadow; // texunit:-3
uniform highp vec4 light_split_offsets;
uniform mediump float fade_from;
uniform mediump float fade_to;
#endif

varying highp vec4 shadow_coord;
Expand Down Expand Up @@ -1987,7 +1989,6 @@ FRAGMENT_SHADER_CODE
float shadow4 = sample_shadow(light_directional_shadow, shadow_coord4);

if (depth_z < light_split_offsets.w) {
float pssm_fade = 0.0;
float shadow_att = 1.0;
#ifdef LIGHT_USE_PSSM_BLEND
float shadow_att2 = 1.0;
Expand Down Expand Up @@ -2023,7 +2024,6 @@ FRAGMENT_SHADER_CODE

} else {
shadow_att = shadow4;
pssm_fade = smoothstep(light_split_offsets.z, light_split_offsets.w, depth_z);

#if defined(LIGHT_USE_PSSM_BLEND)
use_blend = false;
Expand All @@ -2047,7 +2047,6 @@ FRAGMENT_SHADER_CODE
float shadow3 = sample_shadow(light_directional_shadow, shadow_coord3);

if (depth_z < light_split_offsets.z) {
float pssm_fade = 0.0;
float shadow_att = 1.0;
#ifdef LIGHT_USE_PSSM_BLEND
float shadow_att2 = 1.0;
Expand Down Expand Up @@ -2097,15 +2096,13 @@ FRAGMENT_SHADER_CODE

if (depth_z < light_split_offsets.y) {
float shadow_att = 1.0;
float pssm_fade = 0.0;

#ifdef LIGHT_USE_PSSM_BLEND
float shadow_att2 = 1.0;
float pssm_blend = 0.0;
bool use_blend = true;
#endif
if (depth_z < light_split_offsets.x) {
float pssm_fade = 0.0;
shadow_att = shadow1;

#ifdef LIGHT_USE_PSSM_BLEND
Expand All @@ -2114,7 +2111,6 @@ FRAGMENT_SHADER_CODE
#endif
} else {
shadow_att = shadow2;
pssm_fade = smoothstep(light_split_offsets.x, light_split_offsets.y, depth_z);
#ifdef LIGHT_USE_PSSM_BLEND
use_blend = false;
#endif
Expand Down Expand Up @@ -2148,7 +2144,6 @@ FRAGMENT_SHADER_CODE
#endif //pssm2

highp vec4 pssm_coord;
float pssm_fade = 0.0;

#ifdef LIGHT_USE_PSSM_BLEND
float pssm_blend;
Expand Down Expand Up @@ -2187,7 +2182,6 @@ FRAGMENT_SHADER_CODE

} else {
pssm_coord = shadow_coord4;
pssm_fade = smoothstep(light_split_offsets.z, light_split_offsets.w, depth_z);

#if defined(LIGHT_USE_PSSM_BLEND)
use_blend = false;
Expand Down Expand Up @@ -2217,7 +2211,6 @@ FRAGMENT_SHADER_CODE
}
} else {
pssm_coord = shadow_coord3;
pssm_fade = smoothstep(light_split_offsets.y, light_split_offsets.z, depth_z);

#if defined(LIGHT_USE_PSSM_BLEND)
use_blend = false;
Expand All @@ -2236,7 +2229,6 @@ FRAGMENT_SHADER_CODE
#endif
} else {
pssm_coord = shadow_coord2;
pssm_fade = smoothstep(light_split_offsets.x, light_split_offsets.y, depth_z);
#ifdef LIGHT_USE_PSSM_BLEND
use_blend = false;
#endif
Expand All @@ -2258,7 +2250,8 @@ FRAGMENT_SHADER_CODE
}
#endif

light_att *= mix(shadow_color.rgb, vec3(1.0), shadow);
float pssm_fade = smoothstep(fade_from, fade_to, vertex.z);
light_att *= mix(mix(shadow_color.rgb, vec3(1.0), shadow), vec3(1.0), pssm_fade);
}
}
#endif //use vertex lighting
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6 changes: 6 additions & 0 deletions drivers/gles3/rasterizer_scene_gles3.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -2766,6 +2766,7 @@ void RasterizerSceneGLES3::_setup_directional_light(int p_index, const Transform
}
}

// Store the fade distance factor relative to the last split's end.
ubo_data.shadow_split_offsets[j] = li->shadow_transform[j].split;

Transform modelview = (p_camera_inverse_transform * li->shadow_transform[j].transform).affine_inverse();
Expand All @@ -2785,6 +2786,11 @@ void RasterizerSceneGLES3::_setup_directional_light(int p_index, const Transform
ubo_data.light_clamp[2] = atlas_rect.size.x;
ubo_data.light_clamp[3] = atlas_rect.size.y;
}

const float fade_start = li->light_ptr->param[VS::LIGHT_PARAM_SHADOW_FADE_START];
// Using 1.0 would break `smoothstep()` in the shader.
ubo_data.fade_from = -ubo_data.shadow_split_offsets[shadow_count - 1] * MIN(fade_start, 0.999);
ubo_data.fade_to = -ubo_data.shadow_split_offsets[shadow_count - 1];
}

glBindBuffer(GL_UNIFORM_BUFFER, state.directional_ubo);
Expand Down
4 changes: 4 additions & 0 deletions drivers/gles3/rasterizer_scene_gles3.h
Original file line number Diff line number Diff line change
Expand Up @@ -587,6 +587,10 @@ class RasterizerSceneGLES3 : public RasterizerScene {
float matrix[4 * 16];
} shadow;
float shadow_split_offsets[4];

float fade_from;
float fade_to;
float pad[2];
};

struct LightInstance : public RID_Data {
Expand Down
4 changes: 3 additions & 1 deletion drivers/gles3/rasterizer_storage_gles3.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -5450,6 +5450,7 @@ RID RasterizerStorageGLES3::light_create(VS::LightType p_type) {
light->param[VS::LIGHT_PARAM_SHADOW_SPLIT_3_OFFSET] = 0.6;
light->param[VS::LIGHT_PARAM_SHADOW_NORMAL_BIAS] = 0.1;
light->param[VS::LIGHT_PARAM_SHADOW_BIAS_SPLIT_SCALE] = 0.1;
light->param[VS::LIGHT_PARAM_SHADOW_FADE_START] = 0.8;

light->color = Color(1, 1, 1, 1);
light->shadow = false;
Expand Down Expand Up @@ -5486,7 +5487,8 @@ void RasterizerStorageGLES3::light_set_param(RID p_light, VS::LightParam p_param
case VS::LIGHT_PARAM_SHADOW_SPLIT_2_OFFSET:
case VS::LIGHT_PARAM_SHADOW_SPLIT_3_OFFSET:
case VS::LIGHT_PARAM_SHADOW_NORMAL_BIAS:
case VS::LIGHT_PARAM_SHADOW_BIAS: {
case VS::LIGHT_PARAM_SHADOW_BIAS:
case VS::LIGHT_PARAM_SHADOW_FADE_START: {
light->version++;
light->instance_change_notify(true, false);
} break;
Expand Down
13 changes: 9 additions & 4 deletions drivers/gles3/shaders/scene.glsl
Original file line number Diff line number Diff line change
Expand Up @@ -146,6 +146,10 @@ layout(std140) uniform DirectionalLightData { //ubo:3
highp mat4 shadow_matrix3;
highp mat4 shadow_matrix4;
mediump vec4 shadow_split_offsets;

mediump float fade_from;
mediump float fade_to;
mediump vec2 pad;
};

#endif //ubershader-skip
Expand Down Expand Up @@ -842,6 +846,10 @@ layout(std140) uniform DirectionalLightData {
highp mat4 shadow_matrix3;
highp mat4 shadow_matrix4;
mediump vec4 shadow_split_offsets;

mediump float fade_from;
mediump float fade_to;
mediump vec2 pad;
};

uniform highp sampler2DShadow directional_shadow; // texunit:-5
Expand Down Expand Up @@ -2141,7 +2149,6 @@ FRAGMENT_SHADER_CODE
#endif //LIGHT_USE_PSSM4 //ubershader-runtime
if (depth_z < value) {
vec3 pssm_coord;
float pssm_fade = 0.0;

#ifdef LIGHT_USE_PSSM_BLEND //ubershader-skip
float pssm_blend;
Expand Down Expand Up @@ -2187,7 +2194,6 @@ FRAGMENT_SHADER_CODE
} else {
highp vec4 splane = (shadow_matrix4 * vec4(vertex, 1.0));
pssm_coord = splane.xyz / splane.w;
pssm_fade = smoothstep(shadow_split_offsets.z, shadow_split_offsets.w, depth_z);

#ifdef LIGHT_USE_PSSM_BLEND //ubershader-runtime
use_blend = false;
Expand Down Expand Up @@ -2225,7 +2231,6 @@ FRAGMENT_SHADER_CODE
} else {
highp vec4 splane = (shadow_matrix3 * vec4(vertex, 1.0));
pssm_coord = splane.xyz / splane.w;
pssm_fade = smoothstep(shadow_split_offsets.y, shadow_split_offsets.z, depth_z);

#ifdef LIGHT_USE_PSSM_BLEND //ubershader-runtime
use_blend = false;
Expand All @@ -2250,7 +2255,6 @@ FRAGMENT_SHADER_CODE
} else {
highp vec4 splane = (shadow_matrix2 * vec4(vertex, 1.0));
pssm_coord = splane.xyz / splane.w;
pssm_fade = smoothstep(shadow_split_offsets.x, shadow_split_offsets.y, depth_z);
#ifdef LIGHT_USE_PSSM_BLEND //ubershader-runtime
use_blend = false;

Expand Down Expand Up @@ -2287,6 +2291,7 @@ FRAGMENT_SHADER_CODE
shadow = min(shadow, contact_shadow);
}
#endif //ubershader-runtime
float pssm_fade = smoothstep(fade_from, fade_to, vertex.z);
light_attenuation = mix(mix(shadow_color_contact.rgb, vec3(1.0), shadow), vec3(1.0), pssm_fade);
}

Expand Down
4 changes: 4 additions & 0 deletions scene/3d/light.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -267,6 +267,7 @@ void Light::_bind_methods() {
BIND_ENUM_CONSTANT(PARAM_SHADOW_NORMAL_BIAS);
BIND_ENUM_CONSTANT(PARAM_SHADOW_BIAS);
BIND_ENUM_CONSTANT(PARAM_SHADOW_BIAS_SPLIT_SCALE);
BIND_ENUM_CONSTANT(PARAM_SHADOW_FADE_START);
BIND_ENUM_CONSTANT(PARAM_MAX);

BIND_ENUM_CONSTANT(BAKE_DISABLED);
Expand Down Expand Up @@ -314,6 +315,7 @@ Light::Light(VisualServer::LightType p_type) {
set_param(PARAM_SHADOW_SPLIT_1_OFFSET, 0.1);
set_param(PARAM_SHADOW_SPLIT_2_OFFSET, 0.2);
set_param(PARAM_SHADOW_SPLIT_3_OFFSET, 0.5);
set_param(PARAM_SHADOW_FADE_START, 0.8);
set_param(PARAM_SHADOW_NORMAL_BIAS, 0.0);
set_param(PARAM_SHADOW_BIAS, 0.15);
set_disable_scale(true);
Expand Down Expand Up @@ -391,6 +393,7 @@ void DirectionalLight::_bind_methods() {
ADD_PROPERTYI(PropertyInfo(Variant::REAL, "directional_shadow_split_2", PROPERTY_HINT_RANGE, "0,1,0.001"), "set_param", "get_param", PARAM_SHADOW_SPLIT_2_OFFSET);
ADD_PROPERTYI(PropertyInfo(Variant::REAL, "directional_shadow_split_3", PROPERTY_HINT_RANGE, "0,1,0.001"), "set_param", "get_param", PARAM_SHADOW_SPLIT_3_OFFSET);
ADD_PROPERTY(PropertyInfo(Variant::BOOL, "directional_shadow_blend_splits"), "set_blend_splits", "is_blend_splits_enabled");
ADD_PROPERTYI(PropertyInfo(Variant::REAL, "directional_shadow_fade_start", PROPERTY_HINT_RANGE, "0,1,0.01"), "set_param", "get_param", PARAM_SHADOW_FADE_START);
ADD_PROPERTYI(PropertyInfo(Variant::REAL, "directional_shadow_normal_bias", PROPERTY_HINT_RANGE, "0,10,0.001"), "set_param", "get_param", PARAM_SHADOW_NORMAL_BIAS);
ADD_PROPERTYI(PropertyInfo(Variant::REAL, "directional_shadow_bias_split_scale", PROPERTY_HINT_RANGE, "0,1,0.001"), "set_param", "get_param", PARAM_SHADOW_BIAS_SPLIT_SCALE);
ADD_PROPERTY(PropertyInfo(Variant::INT, "directional_shadow_depth_range", PROPERTY_HINT_ENUM, "Stable,Optimized"), "set_shadow_depth_range", "get_shadow_depth_range");
Expand All @@ -411,6 +414,7 @@ DirectionalLight::DirectionalLight() :
set_param(PARAM_SHADOW_BIAS, 0.1);
set_param(PARAM_SHADOW_MAX_DISTANCE, 100);
set_param(PARAM_SHADOW_BIAS_SPLIT_SCALE, 0.25);
set_param(PARAM_SHADOW_FADE_START, 0.8);
set_shadow_mode(SHADOW_PARALLEL_4_SPLITS);
set_shadow_depth_range(SHADOW_DEPTH_RANGE_STABLE);

Expand Down
1 change: 1 addition & 0 deletions scene/3d/light.h
Original file line number Diff line number Diff line change
Expand Up @@ -57,6 +57,7 @@ class Light : public VisualInstance {
PARAM_SHADOW_NORMAL_BIAS = VS::LIGHT_PARAM_SHADOW_NORMAL_BIAS,
PARAM_SHADOW_BIAS = VS::LIGHT_PARAM_SHADOW_BIAS,
PARAM_SHADOW_BIAS_SPLIT_SCALE = VS::LIGHT_PARAM_SHADOW_BIAS_SPLIT_SCALE,
PARAM_SHADOW_FADE_START = VS::LIGHT_PARAM_SHADOW_FADE_START,
PARAM_MAX = VS::LIGHT_PARAM_MAX
};

Expand Down
1 change: 1 addition & 0 deletions servers/visual_server.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -2381,6 +2381,7 @@ void VisualServer::_bind_methods() {
BIND_ENUM_CONSTANT(LIGHT_PARAM_SHADOW_NORMAL_BIAS);
BIND_ENUM_CONSTANT(LIGHT_PARAM_SHADOW_BIAS);
BIND_ENUM_CONSTANT(LIGHT_PARAM_SHADOW_BIAS_SPLIT_SCALE);
BIND_ENUM_CONSTANT(LIGHT_PARAM_SHADOW_FADE_START);
BIND_ENUM_CONSTANT(LIGHT_PARAM_MAX);

BIND_ENUM_CONSTANT(LIGHT_BAKE_DISABLED);
Expand Down
1 change: 1 addition & 0 deletions servers/visual_server.h
Original file line number Diff line number Diff line change
Expand Up @@ -448,6 +448,7 @@ class VisualServer : public Object {
LIGHT_PARAM_SHADOW_NORMAL_BIAS,
LIGHT_PARAM_SHADOW_BIAS,
LIGHT_PARAM_SHADOW_BIAS_SPLIT_SCALE,
LIGHT_PARAM_SHADOW_FADE_START,
LIGHT_PARAM_MAX
};

Expand Down

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