From 8997f2f0174b0008dd38cb32e5076e7d021d3962 Mon Sep 17 00:00:00 2001
From: Kangning Li <likangning93@gmail.com>
Date: Thu, 28 Jun 2018 09:57:16 -0400
Subject: [PATCH] clamp to far plane for polyline on terrain volumes

---
 Source/Shaders/PolylineShadowVolumeFS.glsl | 6 ++++++
 Source/Shaders/PolylineShadowVolumeVS.glsl | 2 +-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/Source/Shaders/PolylineShadowVolumeFS.glsl b/Source/Shaders/PolylineShadowVolumeFS.glsl
index 1042fe7f2c2f..9bd21c42fa50 100644
--- a/Source/Shaders/PolylineShadowVolumeFS.glsl
+++ b/Source/Shaders/PolylineShadowVolumeFS.glsl
@@ -1,3 +1,7 @@
+#ifdef GL_EXT_frag_depth
+#extension GL_EXT_frag_depth : enable
+#endif
+
 varying vec4 v_startPlaneNormalEcAndHalfWidth;
 varying vec4 v_endPlaneNormalEcAndBatchId;
 varying vec4 v_rightPlaneEC; // Technically can compute distance for this here
@@ -78,4 +82,6 @@ void main(void)
     czm_material material = czm_getMaterial(materialInput);
     gl_FragColor = vec4(material.diffuse + material.emission, material.alpha);
 #endif // PER_INSTANCE_COLOR
+
+    czm_writeDepthClampedToFarPlane();
 }
diff --git a/Source/Shaders/PolylineShadowVolumeVS.glsl b/Source/Shaders/PolylineShadowVolumeVS.glsl
index c0ae4e2d1bee..9d17be9312d2 100644
--- a/Source/Shaders/PolylineShadowVolumeVS.glsl
+++ b/Source/Shaders/PolylineShadowVolumeVS.glsl
@@ -157,7 +157,7 @@ void main()
 #endif
 
     positionEC.xyz += width * normalEC;
-    gl_Position = czm_projection * positionEC;
+    gl_Position = czm_depthClampFarPlane(czm_projection * positionEC);
 
 #ifdef ANGLE_VARYING
     // Approximate relative screen space direction of the line.