Fix color properties of particle nodes/material

(cherry picked from commit 3a4a2198edbdd5222eac2746881ceda3b96fbe48)

doc/classes/CPUParticles.xml

@@ -150,10 +150,10 @@
 			Animation speed randomness ratio.
 		</member>
 		<member name="color" type="Color" setter="set_color" getter="get_color" default="Color( 1, 1, 1, 1 )">
-			Unused for 3D particles.
+			Each particle's initial color. To have particle display color in a [SpatialMaterial] make sure to set [member SpatialMaterial.vertex_color_use_as_albedo] to [code]true[/code].
 		</member>
 		<member name="color_ramp" type="Gradient" setter="set_color_ramp" getter="get_color_ramp">
-			Unused for 3D particles.
+			Each particle's color will vary along this [GradientTexture] over its lifetime (multiplied with [member color]).
 		</member>
 		<member name="damping" type="float" setter="set_param" getter="get_param" default="0.0">
 			The rate at which particles lose velocity.

doc/classes/CPUParticles2D.xml

@@ -154,7 +154,7 @@
 			Each particle's initial color. If [member texture] is defined, it will be multiplied by this color.
 		</member>
 		<member name="color_ramp" type="Gradient" setter="set_color_ramp" getter="get_color_ramp">
-			Each particle's color will vary along this [Gradient].
+			Each particle's color will vary along this [Gradient] (multiplied with [member color]).
 		</member>
 		<member name="damping" type="float" setter="set_param" getter="get_param" default="0.0">
 			The rate at which particles lose velocity.

doc/classes/ParticlesMaterial.xml

@@ -135,7 +135,7 @@
 			Each particle's initial color. If the [Particles2D]'s [code]texture[/code] is defined, it will be multiplied by this color. To have particle display color in a [SpatialMaterial] make sure to set [member SpatialMaterial.vertex_color_use_as_albedo] to [code]true[/code].
 		</member>
 		<member name="color_ramp" type="Texture" setter="set_color_ramp" getter="get_color_ramp">
-			Each particle's color will vary along this [GradientTexture].
+			Each particle's color will vary along this [GradientTexture] over its lifetime (multiplied with [member color]).
 		</member>
 		<member name="damping" type="float" setter="set_param" getter="get_param" default="0.0">
 			The rate at which particles lose velocity.

scene/2d/cpu_particles_2d.cpp

@@ -458,10 +458,6 @@ Vector2 CPUParticles2D::get_gravity() const {
 }
 
 void CPUParticles2D::_validate_property(PropertyInfo &property) const {
-	if (property.name == "color" && color_ramp.is_valid()) {
-		property.usage = 0;
-	}
-
 	if (property.name == "emission_sphere_radius" && emission_shape != EMISSION_SHAPE_SPHERE) {
 		property.usage = 0;
 	}

scene/3d/cpu_particles.cpp

@@ -450,10 +450,6 @@ Vector3 CPUParticles::get_gravity() const {
 }
 
 void CPUParticles::_validate_property(PropertyInfo &property) const {
-	if (property.name == "color" && color_ramp.is_valid()) {
-		property.usage = 0;
-	}
-
 	if (property.name == "emission_sphere_radius" && emission_shape != EMISSION_SHAPE_SPHERE) {
 		property.usage = 0;
 	}

scene/resources/particles_material.cpp

@@ -575,7 +575,7 @@ void ParticlesMaterial::_update_shader() {
 	code += "			vec4(1.250, -1.050, -0.203, 0.0),\n";
 	code += "			vec4(0.000, 0.000, 0.000, 0.0)) * hue_rot_s;\n";
 	if (color_ramp.is_valid()) {
-		code += "	COLOR = hue_rot_mat * textureLod(color_ramp, vec2(tv, 0.0), 0.0);\n";
+		code += "	COLOR = hue_rot_mat * textureLod(color_ramp, vec2(tv, 0.0), 0.0) * color_value;\n";
 	} else {
 		code += "	COLOR = hue_rot_mat * color_value;\n";
 	}
@@ -1095,10 +1095,6 @@ RID ParticlesMaterial::get_shader_rid() const {
 }
 
 void ParticlesMaterial::_validate_property(PropertyInfo &property) const {
-	if (property.name == "color" && color_ramp.is_valid()) {
-		property.usage = 0;
-	}
-
 	if (property.name == "emission_sphere_radius" && emission_shape != EMISSION_SHAPE_SPHERE) {
 		property.usage = 0;
 	}