make particle billboard take into account non-uniform scale

scene/resources/material.cpp

@@ -955,11 +955,14 @@ void BaseMaterial3D::_update_shader() {
 		} break;
 		case BILLBOARD_PARTICLES: {
 			//make billboard
-			code += "	mat4 mat_world = mat4(normalize(INV_VIEW_MATRIX[0]) * length(MODEL_MATRIX[0]), normalize(INV_VIEW_MATRIX[1]) * length(MODEL_MATRIX[0]),normalize(INV_VIEW_MATRIX[2]) * length(MODEL_MATRIX[2]), MODEL_MATRIX[3]);\n";
+			code += "	mat4 mat_world = mat4(normalize(INV_VIEW_MATRIX[0]), normalize(INV_VIEW_MATRIX[1]) ,normalize(INV_VIEW_MATRIX[2]), MODEL_MATRIX[3]);\n";
 			//rotate by rotation
 			code += "	mat_world = mat_world * mat4(vec4(cos(INSTANCE_CUSTOM.x), -sin(INSTANCE_CUSTOM.x), 0.0, 0.0), vec4(sin(INSTANCE_CUSTOM.x), cos(INSTANCE_CUSTOM.x), 0.0, 0.0), vec4(0.0, 0.0, 1.0, 0.0), vec4(0.0, 0.0, 0.0, 1.0));\n";
 			//set modelview
 			code += "	MODELVIEW_MATRIX = VIEW_MATRIX * mat_world;\n";
+			if (flags[FLAG_BILLBOARD_KEEP_SCALE]) {
+				code += "	MODELVIEW_MATRIX = MODELVIEW_MATRIX * mat4(vec4(length(MODEL_MATRIX[0].xyz), 0.0, 0.0, 0.0),vec4(0.0, length(MODEL_MATRIX[1].xyz), 0.0, 0.0), vec4(0.0, 0.0, length(MODEL_MATRIX[2].xyz), 0.0), vec4(0.0, 0.0, 0.0, 1.0));\n";
+			}
 			//set modelview normal
 			code += "	MODELVIEW_NORMAL_MATRIX = mat3(MODELVIEW_MATRIX);\n";
 

scene/resources/visual_shader_nodes.cpp

@@ -7606,8 +7606,11 @@ String VisualShaderNodeBillboard::generate_code(Shader::Mode p_mode, VisualShade
 			break;
 		case BILLBOARD_TYPE_PARTICLES:
 			code += "	{\n";
-			code += "		mat4 __wm = mat4(normalize(INV_VIEW_MATRIX[0]) * length(MODEL_MATRIX[0]), normalize(INV_VIEW_MATRIX[1]) * length(MODEL_MATRIX[0]), normalize(INV_VIEW_MATRIX[2]) * length(MODEL_MATRIX[2]), MODEL_MATRIX[3]);\n";
+			code += "		mat4 __wm = mat4(normalize(INV_VIEW_MATRIX[0]), normalize(INV_VIEW_MATRIX[1]), normalize(INV_VIEW_MATRIX[2]), MODEL_MATRIX[3]);\n";
 			code += "		__wm = __wm * mat4(vec4(cos(INSTANCE_CUSTOM.x), -sin(INSTANCE_CUSTOM.x), 0.0, 0.0), vec4(sin(INSTANCE_CUSTOM.x), cos(INSTANCE_CUSTOM.x), 0.0, 0.0), vec4(0.0, 0.0, 1.0, 0.0), vec4(0.0, 0.0, 0.0, 1.0));\n";
+			if (keep_scale) {
+				code += "		__wm = __wm * mat4(vec4(length(MODEL_MATRIX[0].xyz), 0.0, 0.0, 0.0), vec4(0.0, length(MODEL_MATRIX[1].xyz), 0.0, 0.0), vec4(0.0, 0.0, length(MODEL_MATRIX[2].xyz), 0.0), vec4(0.0, 0.0, 0.0, 1.0));\n";
+			}
 			code += "		" + p_output_vars[0] + " = VIEW_MATRIX * __wm;\n";
 			code += "	}\n";
 			break;
@@ -7650,7 +7653,7 @@ bool VisualShaderNodeBillboard::is_keep_scale_enabled() const {
 Vector<StringName> VisualShaderNodeBillboard::get_editable_properties() const {
 	Vector<StringName> props;
 	props.push_back("billboard_type");
-	if (billboard_type == BILLBOARD_TYPE_ENABLED || billboard_type == BILLBOARD_TYPE_FIXED_Y) {
+	if (billboard_type == BILLBOARD_TYPE_ENABLED || billboard_type == BILLBOARD_TYPE_FIXED_Y || billboard_type == BILLBOARD_TYPE_PARTICLES) {
 		props.push_back("keep_scale");
 	}
 	return props;