simulator: add red circle model for recognizing

clover_simulation/models/red_circle/materials/scripts/red_circle.material

@@ -0,0 +1,16 @@
+material red_circle
+{
+	technique
+	{
+		pass
+		{
+			scene_blend alpha_blend
+			texture_unit
+			{
+				texture red_circle.png
+				filtering none
+				scale 1.0 1.0
+			}
+		}
+	}
+}

clover_simulation/models/red_circle/model.config

@@ -0,0 +1,13 @@
+<?xml version="1.0"?>
+<model>
+    <name>Red Circle</name>
+    <version>1.0</version>
+    <sdf version="1.5">red_circle.sdf</sdf>
+    <author>
+        <name>Oleg Kalachev</name>
+        <email>okalachev@gmail.com</email>
+    </author>
+    <description>
+        Red circle of size 40 cm on the floor for recognizing by a drone
+    </description>
+</model>

clover_simulation/models/red_circle/red_circle.sdf

@@ -0,0 +1,24 @@
+<?xml version="1.0"?>
+<sdf version="1.5">
+    <model name="red_circle">
+        <static>true</static>
+        <link name="red_circle_link">
+            <pose>0 0 1e-3 0 0 0</pose>
+            <visual name="red_circle_texture">
+                <cast_shadows>false</cast_shadows>
+                <geometry>
+                    <box>
+                        <size>0.4 0.4 1e-3</size>
+                    </box>
+                </geometry>
+                <material>
+                    <script>
+                        <uri>model://red_circle/materials/scripts</uri>
+                        <uri>model://red_circle/materials/textures</uri>
+                        <name>red_circle</name>
+                    </script>
+                </material>
+            </visual>
+        </link>
+    </model>
+</sdf>

clover_simulation/models/red_circle/red_circle.svg

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 20 20">
+	<title>
+		red_circle
+	</title><g fill="red">
+	<circle cx="10.05" cy="10.05" r="9.9"/>
+</g></svg>