Implement shadow to opacity

7 files changed, 94 insertions, 29 deletions

diff --git a/drivers/gles2/shader_compiler_gles2.cpp b/drivers/gles2/shader_compiler_gles2.cpp
index d00b03fb8a..6ba4004f20 100644
--- a/drivers/gles2/shader_compiler_gles2.cpp
+++ b/drivers/gles2/shader_compiler_gles2.cpp
@@ -934,6 +934,7 @@ ShaderCompilerGLES2::ShaderCompilerGLES2() {
 	actions[VS::SHADER_SPATIAL].render_mode_defines["specular_disabled"] = "#define SPECULAR_DISABLED\n";
 	actions[VS::SHADER_SPATIAL].render_mode_defines["shadows_disabled"] = "#define SHADOWS_DISABLED\n";
 	actions[VS::SHADER_SPATIAL].render_mode_defines["ambient_light_disabled"] = "#define AMBIENT_LIGHT_DISABLED\n";
+	actions[VS::SHADER_SPATIAL].render_mode_defines["shadow_to_opacity"] = "#define USE_SHADOW_TO_OPACITY\n";
 
 	// No defines for particle shaders in GLES2, there are no GPU particles
 
diff --git a/drivers/gles2/shaders/scene.glsl b/drivers/gles2/shaders/scene.glsl
index 0fa290e57c..ac5af31153 100644
--- a/drivers/gles2/shaders/scene.glsl
+++ b/drivers/gles2/shaders/scene.glsl
@@ -1151,7 +1151,8 @@ void light_compute(
 		float clearcoat_gloss,
 		float anisotropy,
 		inout vec3 diffuse_light,
-		inout vec3 specular_light) {
+		inout vec3 specular_light,
+		inout float alpha) {
 
 //this makes lights behave closer to linear, but then addition of lights looks bad
 //better left disabled
@@ -1306,10 +1307,10 @@ LIGHT_SHADER_CODE
 		// shlick+ggx as default
 
 #if defined(LIGHT_USE_ANISOTROPY)
-		float alpha = roughness * roughness;
+		float alpha_ggx = roughness * roughness;
 		float aspect = sqrt(1.0 - anisotropy * 0.9);
-		float ax = alpha / aspect;
-		float ay = alpha * aspect;
+		float ax = alpha_ggx / aspect;
+		float ay = alpha_ggx * aspect;
 		float XdotH = dot(T, H);
 		float YdotH = dot(B, H);
 		float D = D_GGX_anisotropic(cNdotH, ax, ay, XdotH, YdotH, cNdotH);
@@ -1317,10 +1318,10 @@ LIGHT_SHADER_CODE
 		float G = V_GGX_anisotropic(ax, ay, dot(T, V), dot(T, L), dot(B, V), dot(B, L), cNdotV, cNdotL);
 
 #else
-		float alpha = roughness * roughness;
-		float D = D_GGX(cNdotH, alpha);
-		//float G = G_GGX_2cos(cNdotL, alpha) * G_GGX_2cos(cNdotV, alpha);
-		float G = V_GGX(cNdotL, cNdotV, alpha);
+		float alpha_ggx = roughness * roughness;
+		float D = D_GGX(cNdotH, alpha_ggx);
+		//float G = G_GGX_2cos(cNdotL, alpha_ggx) * G_GGX_2cos(cNdotV, alpha_ggx);
+		float G = V_GGX(cNdotL, cNdotV, alpha_ggx);
 #endif
 		// F
 		vec3 f0 = F0(metallic, specular, diffuse_color);
@@ -1350,6 +1351,10 @@ LIGHT_SHADER_CODE
 #endif
 	}
 
+#ifdef USE_SHADOW_TO_OPACITY
+	alpha = min(alpha, clamp(1.0 - length(attenuation), 0.0, 1.0));
+#endif
+
 #endif //defined(USE_LIGHT_SHADER_CODE)
 }
 
@@ -1535,17 +1540,21 @@ FRAGMENT_SHADER_CODE
 
 	vec3 eye_position = view;
 
+#if !defined(USE_SHADOW_TO_OPACITY)
+
 #if defined(ALPHA_SCISSOR_USED)
 	if (alpha < alpha_scissor) {
 		discard;
 	}
-#endif
+#endif // ALPHA_SCISSOR_USED
 
 #ifdef USE_DEPTH_PREPASS
 	if (alpha < 0.99) {
 		discard;
 	}
-#endif
+#endif // USE_DEPTH_PREPASS
+
+#endif // !USE_SHADOW_TO_OPACITY
 
 #ifdef BASE_PASS
 	//none
@@ -2061,13 +2070,32 @@ FRAGMENT_SHADER_CODE
 			clearcoat_gloss,
 			anisotropy,
 			diffuse_light,
-			specular_light);
+			specular_light,
+			alpha);
 
 #endif //vertex lighting
 
 #endif //USE_LIGHTING
 	//compute and merge
 
+#ifdef USE_SHADOW_TO_OPACITY
+
+	alpha = min(alpha, clamp(length(ambient_light), 0.0, 1.0));
+
+#if defined(ALPHA_SCISSOR_USED)
+	if (alpha < alpha_scissor) {
+		discard;
+	}
+#endif // ALPHA_SCISSOR_USED
+
+#ifdef USE_DEPTH_PREPASS
+	if (alpha < 0.99) {
+		discard;
+	}
+#endif // USE_DEPTH_PREPASS
+
+#endif // !USE_SHADOW_TO_OPACITY
+
 #ifndef RENDER_DEPTH
 
 #ifdef SHADELESS
diff --git a/drivers/gles3/shader_compiler_gles3.cpp b/drivers/gles3/shader_compiler_gles3.cpp
index ad26294527..e8417900ea 100644
--- a/drivers/gles3/shader_compiler_gles3.cpp
+++ b/drivers/gles3/shader_compiler_gles3.cpp
@@ -944,6 +944,7 @@ ShaderCompilerGLES3::ShaderCompilerGLES3() {
 	actions[VS::SHADER_SPATIAL].render_mode_defines["specular_disabled"] = "#define SPECULAR_DISABLED\n";
 	actions[VS::SHADER_SPATIAL].render_mode_defines["shadows_disabled"] = "#define SHADOWS_DISABLED\n";
 	actions[VS::SHADER_SPATIAL].render_mode_defines["ambient_light_disabled"] = "#define AMBIENT_LIGHT_DISABLED\n";
+	actions[VS::SHADER_SPATIAL].render_mode_defines["shadow_to_opacity"] = "#define USE_SHADOW_TO_OPACITY\n";
 
 	/* PARTICLES SHADER */
 
diff --git a/drivers/gles3/shaders/scene.glsl b/drivers/gles3/shaders/scene.glsl
index def924cd49..844028607d 100644
--- a/drivers/gles3/shaders/scene.glsl
+++ b/drivers/gles3/shaders/scene.glsl
@@ -993,7 +993,7 @@ vec3 F0(float metallic, float specular, vec3 albedo) {
 	return mix(vec3(dielectric), albedo, vec3(metallic));
 }
 
-void light_compute(vec3 N, vec3 L, vec3 V, vec3 B, vec3 T, vec3 light_color, vec3 attenuation, vec3 diffuse_color, vec3 transmission, float specular_blob_intensity, float roughness, float metallic, float specular, float rim, float rim_tint, float clearcoat, float clearcoat_gloss, float anisotropy, inout vec3 diffuse_light, inout vec3 specular_light) {
+void light_compute(vec3 N, vec3 L, vec3 V, vec3 B, vec3 T, vec3 light_color, vec3 attenuation, vec3 diffuse_color, vec3 transmission, float specular_blob_intensity, float roughness, float metallic, float specular, float rim, float rim_tint, float clearcoat, float clearcoat_gloss, float anisotropy, inout vec3 diffuse_light, inout vec3 specular_light, inout float alpha) {
 
 #if defined(USE_LIGHT_SHADER_CODE)
 	// light is written by the light shader
@@ -1135,19 +1135,19 @@ LIGHT_SHADER_CODE
 
 #if defined(LIGHT_USE_ANISOTROPY)
 
-		float alpha = roughness * roughness;
+		float alpha_ggx = roughness * roughness;
 		float aspect = sqrt(1.0 - anisotropy * 0.9);
-		float ax = alpha / aspect;
-		float ay = alpha * aspect;
+		float ax = alpha_ggx / aspect;
+		float ay = alpha_ggx * aspect;
 		float XdotH = dot(T, H);
 		float YdotH = dot(B, H);
 		float D = D_GGX_anisotropic(cNdotH, ax, ay, XdotH, YdotH);
 		float G = G_GGX_anisotropic_2cos(cNdotL, ax, ay, XdotH, YdotH) * G_GGX_anisotropic_2cos(cNdotV, ax, ay, XdotH, YdotH);
 
 #else
-		float alpha = roughness * roughness;
-		float D = D_GGX(cNdotH, alpha);
-		float G = G_GGX_2cos(cNdotL, alpha) * G_GGX_2cos(cNdotV, alpha);
+		float alpha_ggx = roughness * roughness;
+		float D = D_GGX(cNdotH, alpha_ggx);
+		float G = G_GGX_2cos(cNdotL, alpha_ggx) * G_GGX_2cos(cNdotV, alpha_ggx);
 #endif
 		// F
 		vec3 f0 = F0(metallic, specular, diffuse_color);
@@ -1174,6 +1174,10 @@ LIGHT_SHADER_CODE
 #endif
 	}
 
+#ifdef USE_SHADOW_TO_OPACITY
+	alpha = min(alpha, clamp(1.0 - length(attenuation), 0.0, 1.0));
+#endif
+
 #endif //defined(USE_LIGHT_SHADER_CODE)
 }
 
@@ -1250,7 +1254,7 @@ vec3 light_transmittance(float translucency,vec3 light_vec, vec3 normal, vec3 po
 }
 #endif
 
-void light_process_omni(int idx, vec3 vertex, vec3 eye_vec, vec3 normal, vec3 binormal, vec3 tangent, vec3 albedo, vec3 transmission, float roughness, float metallic, float specular, float rim, float rim_tint, float clearcoat, float clearcoat_gloss, float anisotropy, float p_blob_intensity, inout vec3 diffuse_light, inout vec3 specular_light) {
+void light_process_omni(int idx, vec3 vertex, vec3 eye_vec, vec3 normal, vec3 binormal, vec3 tangent, vec3 albedo, vec3 transmission, float roughness, float metallic, float specular, float rim, float rim_tint, float clearcoat, float clearcoat_gloss, float anisotropy, float p_blob_intensity, inout vec3 diffuse_light, inout vec3 specular_light, inout float alpha) {
 
 	vec3 light_rel_vec = omni_lights[idx].light_pos_inv_radius.xyz - vertex;
 	float light_length = length(light_rel_vec);
@@ -1304,10 +1308,10 @@ void light_process_omni(int idx, vec3 vertex, vec3 eye_vec, vec3 normal, vec3 bi
 		light_attenuation *= mix(omni_lights[idx].shadow_color_contact.rgb, vec3(1.0), shadow);
 	}
 #endif //SHADOWS_DISABLED
-	light_compute(normal, normalize(light_rel_vec), eye_vec, binormal, tangent, omni_lights[idx].light_color_energy.rgb, light_attenuation, albedo, transmission, omni_lights[idx].light_params.z * p_blob_intensity, roughness, metallic, specular, rim * omni_attenuation, rim_tint, clearcoat, clearcoat_gloss, anisotropy, diffuse_light, specular_light);
+	light_compute(normal, normalize(light_rel_vec), eye_vec, binormal, tangent, omni_lights[idx].light_color_energy.rgb, light_attenuation, albedo, transmission, omni_lights[idx].light_params.z * p_blob_intensity, roughness, metallic, specular, rim * omni_attenuation, rim_tint, clearcoat, clearcoat_gloss, anisotropy, diffuse_light, specular_light, alpha);
 }
 
-void light_process_spot(int idx, vec3 vertex, vec3 eye_vec, vec3 normal, vec3 binormal, vec3 tangent, vec3 albedo, vec3 transmission, float roughness, float metallic, float specular, float rim, float rim_tint, float clearcoat, float clearcoat_gloss, float anisotropy, float p_blob_intensity, inout vec3 diffuse_light, inout vec3 specular_light) {
+void light_process_spot(int idx, vec3 vertex, vec3 eye_vec, vec3 normal, vec3 binormal, vec3 tangent, vec3 albedo, vec3 transmission, float roughness, float metallic, float specular, float rim, float rim_tint, float clearcoat, float clearcoat_gloss, float anisotropy, float p_blob_intensity, inout vec3 diffuse_light, inout vec3 specular_light, inout float alpha) {
 
 	vec3 light_rel_vec = spot_lights[idx].light_pos_inv_radius.xyz - vertex;
 	float light_length = length(light_rel_vec);
@@ -1339,7 +1343,7 @@ void light_process_spot(int idx, vec3 vertex, vec3 eye_vec, vec3 normal, vec3 bi
 	}
 #endif //SHADOWS_DISABLED
 
-	light_compute(normal, normalize(light_rel_vec), eye_vec, binormal, tangent, spot_lights[idx].light_color_energy.rgb, light_attenuation, albedo, transmission, spot_lights[idx].light_params.z * p_blob_intensity, roughness, metallic, specular, rim * spot_attenuation, rim_tint, clearcoat, clearcoat_gloss, anisotropy, diffuse_light, specular_light);
+	light_compute(normal, normalize(light_rel_vec), eye_vec, binormal, tangent, spot_lights[idx].light_color_energy.rgb, light_attenuation, albedo, transmission, spot_lights[idx].light_params.z * p_blob_intensity, roughness, metallic, specular, rim * spot_attenuation, rim_tint, clearcoat, clearcoat_gloss, anisotropy, diffuse_light, specular_light, alpha);
 }
 
 void reflection_process(int idx, vec3 vertex, vec3 normal, vec3 binormal, vec3 tangent, float roughness, float anisotropy, vec3 ambient, vec3 skybox, inout highp vec4 reflection_accum, inout highp vec4 ambient_accum) {
@@ -1705,11 +1709,13 @@ FRAGMENT_SHADER_CODE
 		/* clang-format on */
 	}
 
+#if !defined(USE_SHADOW_TO_OPACITY)
+
 #if defined(ALPHA_SCISSOR_USED)
 	if (alpha < alpha_scissor) {
 		discard;
 	}
-#endif
+#endif // ALPHA_SCISSOR_USED
 
 #ifdef USE_OPAQUE_PREPASS
 
@@ -1717,7 +1723,9 @@ FRAGMENT_SHADER_CODE
 		discard;
 	}
 
-#endif
+#endif // USE_OPAQUE_PREPASS
+
+#endif // !USE_SHADOW_TO_OPACITY
 
 #if defined(ENABLE_NORMALMAP)
 
@@ -1970,7 +1978,7 @@ FRAGMENT_SHADER_CODE
 	specular_light *= mix(vec3(1.0), light_attenuation, specular_light_interp.a);
 
 #else
-	light_compute(normal, -light_direction_attenuation.xyz, eye_vec, binormal, tangent, light_color_energy.rgb, light_attenuation, albedo, transmission, light_params.z * specular_blob_intensity, roughness, metallic, specular, rim, rim_tint, clearcoat, clearcoat_gloss, anisotropy, diffuse_light, specular_light);
+	light_compute(normal, -light_direction_attenuation.xyz, eye_vec, binormal, tangent, light_color_energy.rgb, light_attenuation, albedo, transmission, light_params.z * specular_blob_intensity, roughness, metallic, specular, rim, rim_tint, clearcoat, clearcoat_gloss, anisotropy, diffuse_light, specular_light, alpha);
 #endif
 
 #endif //#USE_LIGHT_DIRECTIONAL
@@ -2044,17 +2052,36 @@ FRAGMENT_SHADER_CODE
 #else
 
 	for (int i = 0; i < omni_light_count; i++) {
-		light_process_omni(omni_light_indices[i], vertex, eye_vec, normal, binormal, tangent, albedo, transmission, roughness, metallic, specular, rim, rim_tint, clearcoat, clearcoat_gloss, anisotropy, specular_blob_intensity, diffuse_light, specular_light);
+		light_process_omni(omni_light_indices[i], vertex, eye_vec, normal, binormal, tangent, albedo, transmission, roughness, metallic, specular, rim, rim_tint, clearcoat, clearcoat_gloss, anisotropy, specular_blob_intensity, diffuse_light, specular_light, alpha);
 	}
 
 	for (int i = 0; i < spot_light_count; i++) {
-		light_process_spot(spot_light_indices[i], vertex, eye_vec, normal, binormal, tangent, albedo, transmission, roughness, metallic, specular, rim, rim_tint, clearcoat, clearcoat_gloss, anisotropy, specular_blob_intensity, diffuse_light, specular_light);
+		light_process_spot(spot_light_indices[i], vertex, eye_vec, normal, binormal, tangent, albedo, transmission, roughness, metallic, specular, rim, rim_tint, clearcoat, clearcoat_gloss, anisotropy, specular_blob_intensity, diffuse_light, specular_light, alpha);
 	}
 
 #endif //USE_VERTEX_LIGHTING
 
 #endif
 
+#ifdef USE_SHADOW_TO_OPACITY
+	alpha = min(alpha, clamp(length(ambient_light), 0.0, 1.0));
+
+#if defined(ALPHA_SCISSOR_USED)
+	if (alpha < alpha_scissor) {
+		discard;
+	}
+#endif // ALPHA_SCISSOR_USED
+
+#ifdef USE_OPAQUE_PREPASS
+
+	if (alpha < opaque_prepass_threshold) {
+		discard;
+	}
+
+#endif // USE_OPAQUE_PREPASS
+
+#endif // USE_SHADOW_TO_OPACITY
+
 #ifdef RENDER_DEPTH
 //nothing happens, so a tree-ssa optimizer will result in no fragment shader :)
 #else
diff --git a/scene/resources/material.cpp b/scene/resources/material.cpp
index 766c7bbd9f..2e035bbd1f 100644
--- a/scene/resources/material.cpp
+++ b/scene/resources/material.cpp
@@ -468,6 +468,9 @@ void SpatialMaterial::_update_shader() {
 	if (flags[FLAG_ENSURE_CORRECT_NORMALS]) {
 		code += ",ensure_correct_normals";
 	}
+	if (flags[FLAG_USE_SHADOW_TO_OPACITY]) {
+		code += ",shadow_to_opacity";
+	}
 	code += ";\n";
 
 	code += "uniform vec4 albedo : hint_color;\n";
@@ -849,7 +852,7 @@ void SpatialMaterial::_update_shader() {
 		code += "\tALBEDO *= 1.0 - ref_amount;\n";
 		code += "\tALPHA = 1.0;\n";
 
-	} else if (features[FEATURE_TRANSPARENT] || flags[FLAG_USE_ALPHA_SCISSOR] || (distance_fade == DISTANCE_FADE_PIXEL_ALPHA) || proximity_fade_enabled) {
+	} else if (features[FEATURE_TRANSPARENT] || flags[FLAG_USE_ALPHA_SCISSOR] || flags[FLAG_USE_SHADOW_TO_OPACITY] || (distance_fade == DISTANCE_FADE_PIXEL_ALPHA) || proximity_fade_enabled) {
 		code += "\tALPHA = albedo.a * albedo_tex.a;\n";
 	}
 
@@ -1349,7 +1352,7 @@ void SpatialMaterial::set_flag(Flags p_flag, bool p_enabled) {
 		return;
 
 	flags[p_flag] = p_enabled;
-	if (p_flag == FLAG_USE_ALPHA_SCISSOR || p_flag == FLAG_UNSHADED) {
+	if ((p_flag == FLAG_USE_ALPHA_SCISSOR) || (p_flag == FLAG_UNSHADED) || (p_flag == FLAG_USE_SHADOW_TO_OPACITY)) {
 		_change_notify();
 	}
 	_queue_shader_change();
@@ -2060,6 +2063,7 @@ void SpatialMaterial::_bind_methods() {
 
 	ADD_GROUP("Flags", "flags_");
 	ADD_PROPERTYI(PropertyInfo(Variant::BOOL, "flags_transparent"), "set_feature", "get_feature", FEATURE_TRANSPARENT);
+	ADD_PROPERTYI(PropertyInfo(Variant::BOOL, "flags_use_shadow_to_opacity"), "set_flag", "get_flag", FLAG_USE_SHADOW_TO_OPACITY);
 	ADD_PROPERTYI(PropertyInfo(Variant::BOOL, "flags_unshaded"), "set_flag", "get_flag", FLAG_UNSHADED);
 	ADD_PROPERTYI(PropertyInfo(Variant::BOOL, "flags_vertex_lighting"), "set_flag", "get_flag", FLAG_USE_VERTEX_LIGHTING);
 	ADD_PROPERTYI(PropertyInfo(Variant::BOOL, "flags_no_depth_test"), "set_flag", "get_flag", FLAG_DISABLE_DEPTH_TEST);
@@ -2266,6 +2270,7 @@ void SpatialMaterial::_bind_methods() {
 	BIND_ENUM_CONSTANT(FLAG_DONT_RECEIVE_SHADOWS);
 	BIND_ENUM_CONSTANT(FLAG_DISABLE_AMBIENT_LIGHT);
 	BIND_ENUM_CONSTANT(FLAG_ENSURE_CORRECT_NORMALS);
+	BIND_ENUM_CONSTANT(FLAG_USE_SHADOW_TO_OPACITY);
 	BIND_ENUM_CONSTANT(FLAG_MAX);
 
 	BIND_ENUM_CONSTANT(DIFFUSE_BURLEY);
diff --git a/scene/resources/material.h b/scene/resources/material.h
index 1f7fc267af..29b45f769b 100644
--- a/scene/resources/material.h
+++ b/scene/resources/material.h
@@ -196,6 +196,7 @@ public:
 		FLAG_DONT_RECEIVE_SHADOWS,
 		FLAG_ENSURE_CORRECT_NORMALS,
 		FLAG_DISABLE_AMBIENT_LIGHT,
+		FLAG_USE_SHADOW_TO_OPACITY,
 		FLAG_MAX
 	};
 
diff --git a/servers/visual/shader_types.cpp b/servers/visual/shader_types.cpp
index 8fd5dfc738..bc6010117c 100644
--- a/servers/visual/shader_types.cpp
+++ b/servers/visual/shader_types.cpp
@@ -147,6 +147,7 @@ ShaderTypes::ShaderTypes() {
 	shader_modes[VS::SHADER_SPATIAL].functions["light"].built_ins["DIFFUSE_LIGHT"] = ShaderLanguage::TYPE_VEC3;
 	shader_modes[VS::SHADER_SPATIAL].functions["light"].built_ins["SPECULAR_LIGHT"] = ShaderLanguage::TYPE_VEC3;
 	shader_modes[VS::SHADER_SPATIAL].functions["light"].built_ins["OUTPUT_IS_SRGB"] = constt(ShaderLanguage::TYPE_BOOL);
+	shader_modes[VS::SHADER_SPATIAL].functions["light"].built_ins["ALPHA"] = ShaderLanguage::TYPE_FLOAT;
 
 	shader_modes[VS::SHADER_SPATIAL].functions["light"].can_discard = true;
 
@@ -187,6 +188,7 @@ ShaderTypes::ShaderTypes() {
 
 	shader_modes[VS::SHADER_SPATIAL].modes.push_back("shadows_disabled");
 	shader_modes[VS::SHADER_SPATIAL].modes.push_back("ambient_light_disabled");
+	shader_modes[VS::SHADER_SPATIAL].modes.push_back("shadow_to_opacity");
 
 	shader_modes[VS::SHADER_SPATIAL].modes.push_back("vertex_lighting");