Hi, I am experimenting with Gazebo SDF world files.
I noticed that when I turn on the <cast_shadow> property of a directional light I added to the world, the sky starts “flickering” with weird horizontal lines.
Here is a screenshot of the simulation and the SDF file:
<?xml version="1.0"?>
<sdf version="1.8">
<world name="test">
<scene>
<ambient>1.0 1.0 1.0 1.0</ambient>
<background>0.5 0.5 0.5 1.0</background>
<sky>
<time>10.0</time>
<sunrise>6.0</sunrise>
<sunset>18.0</sunset>
</sky>
<shadows>True</shadows>
<grid>True</grid>
<origin_visual>True</origin_visual>
</scene>
<light name="Sun" type="directional">
<diffuse>0.7 0.7 0.7 0.0</diffuse>
<specular>1.0 1.0 1.0 0.0</specular>
<direction>-1.0 -1.0 -1.0</direction>
<cast_shadows>True</cast_shadows>
</light>
<model name="ground">
<static>True</static>
<link name="ground">
<pose>0 0 -0.25 0.0 0.0 0.0</pose>
<inertial>
<mass>1.0</mass>
<inertia>
<ixx>1.0</ixx>
<iyy>1.0</iyy>
<izz>1.0</izz>
<ixy>0.0</ixy>
<ixz>0.0</ixz>
<iyz>0.0</iyz>
</inertia>
</inertial>
<collision name="visual">
<geometry>
<box>
<size>100.0 100.0 0.5</size>
</box>
</geometry>
</collision>
<visual name="visual">
<geometry>
<box>
<size>100.0 100.0 0.5</size>
</box>
</geometry>
<material>
<ambient>0.5 0.5 0.5 1.0</ambient>
<diffuse>0.5 0.5 0.5 1.0</diffuse>
<specular>0 0 0 0</specular>
<emissive>0 0 0 1</emissive>
</material>
</visual>
</link>
</model>
<model name="box">
<static>True</static>
<link name="box">
<pose>0.0 0.0 2.0 0.0 0.0 0.0</pose>
<inertial>
<mass>1.0</mass>
<inertia>
<ixx>1.0</ixx>
<iyy>1.0</iyy>
<izz>1.0</izz>
<ixy>0.0</ixy>
<ixz>0.0</ixz>
<iyz>0.0</iyz>
</inertia>
</inertial>
<collision name="visual">
<geometry>
<box>
<size>1.0 1.0 1.0</size>
</box>
</geometry>
</collision>
<visual name="visual">
<geometry>
<box>
<size>1.0 1.0 1.0</size>
</box>
</geometry>
<material>
<ambient>0.0 0.0 1.0 1.0</ambient>
<diffuse>0.0 0.0 1.0 1.0</diffuse>
<specular>0 0 0 0</specular>
<emissive>0 0 0 1</emissive>
</material>
</visual>
</link>
</model>
<model name="cylinder">
<static>True</static>
<link name="cylinder">
<pose>2.0 1.0 2.0 0.0 0.0 0.0</pose>
<inertial>
<mass>1.0</mass>
<inertia>
<ixx>1.0</ixx>
<iyy>1.0</iyy>
<izz>1.0</izz>
<ixy>0.0</ixy>
<ixz>0.0</ixz>
<iyz>0.0</iyz>
</inertia>
</inertial>
<collision name="visual">
<geometry>
<cylinder>
<radius>1.0</radius>
<length>1.0</length>
</cylinder>
</geometry>
</collision>
<visual name="visual">
<geometry>
<cylinder>
<radius>1.0</radius>
<length>1.0</length>
</cylinder>
</geometry>
<material>
<ambient>0.0 1.0 0.0 1.0</ambient>
<diffuse>0.0 1.0 0.0 1.0</diffuse>
<specular>0 0 0 0</specular>
<emissive>0 0 0 1</emissive>
</material>
</visual>
</link>
</model>
<model name="sphere">
<static>True</static>
<link name="sphere">
<pose>0.1 -5.0 2.0 0.0 0.0 0.0</pose>
<inertial>
<mass>1.0</mass>
<inertia>
<ixx>1.0</ixx>
<iyy>1.0</iyy>
<izz>1.0</izz>
<ixy>0.0</ixy>
<ixz>0.0</ixz>
<iyz>0.0</iyz>
</inertia>
</inertial>
<collision name="visual">
<geometry>
<sphere>
<radius>1.0</radius>
</sphere>
</geometry>
</collision>
<visual name="visual">
<geometry>
<sphere>
<radius>1.0</radius>
</sphere>
</geometry>
<material>
<ambient>1.0 0.0 0.0 1.0</ambient>
<diffuse>1.0 0.0 0.0 1.0</diffuse>
<specular>0 0 0 0</specular>
<emissive>0 0 0 1</emissive>
</material>
</visual>
</link>
</model>
</world>
</sdf>