Fixed unsuported R8 texture format in GLES2.

ScriptableRenderPipeline/LightweightPipeline/LWRP/LightweightPipeline.cs

         public Vector3  directionalLightCascades;
         public float    directionalLightNearPlaneOffset;
 
-        public RenderTextureFormat renderTextureFormat;
+        public RenderTextureFormat shadowmapTextureFormat;
+        public RenderTextureFormat screenspaceShadowmapTextureFormat;
 
         static ShadowSettings defaultShadowSettings = null;
 
                     defaultShadowSettings.directionalLightCascades = new Vector3(0.05F, 0.2F, 0.3F);
                     defaultShadowSettings.directionalLightNearPlaneOffset = 5;
                     defaultShadowSettings.maxShadowDistance = 1000.0F;
-                    defaultShadowSettings.renderTextureFormat = RenderTextureFormat.Shadowmap;
+                    defaultShadowSettings.shadowmapTextureFormat = RenderTextureFormat.Shadowmap;
+                    defaultShadowSettings.screenspaceShadowmapTextureFormat = RenderTextureFormat.R8;
                 }
                 return defaultShadowSettings;
             }
                 if (!shadows)
                 {
                     var setRT = CommandBufferPool.Get("Generate Small Shadow Buffer");
-                    int shadowmapID = m_ShadowSettings.screenSpace ? m_ScreenSpaceShadowMapRTID : m_ShadowMapRTID;
-                    setRT.GetTemporaryRT(shadowmapID, 4, 4, 0, FilterMode.Bilinear, RenderTextureFormat.ARGB32);
+                    if (m_ShadowSettings.screenSpace)
+                        setRT.GetTemporaryRT(m_ScreenSpaceShadowMapRTID, 4, 4, 0, FilterMode.Bilinear, m_ShadowSettings.screenspaceShadowmapTextureFormat);
+                    else
+                        setRT.GetTemporaryRT(m_ShadowMapRTID, 4, 4, 0, FilterMode.Bilinear, m_ShadowSettings.shadowmapTextureFormat);
                     setRT.Blit(Texture2D.whiteTexture, m_ScreenSpaceShadowMapRT);
                     context.ExecuteCommandBuffer(setRT);
                 }
             {
                 var desc = XRSettings.eyeTextureDesc;
                 desc.depthBufferBits = 0;
-                desc.colorFormat = RenderTextureFormat.R8;
+                desc.colorFormat = m_ShadowSettings.screenspaceShadowmapTextureFormat;
-                cmd.GetTemporaryRT(m_ScreenSpaceShadowMapRTID, m_CurrCamera.pixelWidth, m_CurrCamera.pixelHeight, 0, FilterMode.Bilinear, RenderTextureFormat.R8);
+                cmd.GetTemporaryRT(m_ScreenSpaceShadowMapRTID, m_CurrCamera.pixelWidth, m_CurrCamera.pixelHeight, 0, FilterMode.Bilinear, m_ShadowSettings.screenspaceShadowmapTextureFormat);
-            // Note: The source isn't actually 'used', but there's an engine peculiarity (bug) that 
+            // Note: The source isn't actually 'used', but there's an engine peculiarity (bug) that
             // doesn't like null sources when trying to determine a stereo-ized blit.  So for proper
             // stereo functionality, we use the screen-space shadow map as the source (until we have
             // a better solution).
             m_ShadowSettings.shadowAtlasWidth = m_Asset.ShadowAtlasResolution;
             m_ShadowSettings.shadowAtlasHeight = m_Asset.ShadowAtlasResolution;
             m_ShadowSettings.maxShadowDistance = m_Asset.ShadowDistance;
-            m_ShadowSettings.renderTextureFormat = SystemInfo.SupportsRenderTextureFormat(RenderTextureFormat.Shadowmap)
+            m_ShadowSettings.shadowmapTextureFormat = SystemInfo.SupportsRenderTextureFormat(RenderTextureFormat.Shadowmap)
+
+            m_ShadowSettings.screenspaceShadowmapTextureFormat = SystemInfo.SupportsRenderTextureFormat(RenderTextureFormat.R8)
+                    ? RenderTextureFormat.R8
+                    : RenderTextureFormat.ARGB32;
 
             switch (m_ShadowSettings.directionalLightCascadeCount)
             {
 
             var cmd = CommandBufferPool.Get("Prepare Shadowmap");
             cmd.GetTemporaryRT(m_ShadowMapRTID, m_ShadowSettings.shadowAtlasWidth,
-                m_ShadowSettings.shadowAtlasHeight, kShadowBufferBits, FilterMode.Bilinear, m_ShadowSettings.renderTextureFormat);
+                m_ShadowSettings.shadowAtlasHeight, kShadowBufferBits, FilterMode.Bilinear, m_ShadowSettings.shadowmapTextureFormat);
             // LightweightPipeline.SetRenderTarget is meant to be used with camera targets, not shadowmaps
             CoreUtils.SetRenderTarget(cmd, m_ShadowMapRT, ClearFlag.Depth, CoreUtils.ConvertSRGBToActiveColorSpace(m_CurrCamera.backgroundColor));