add linear_depth material

materials/build.sh

@@ -1,4 +1,4 @@
-for material in image unlit_fixed_size grid; do \
+for material in image unlit_fixed_size grid linear_depth; do \
     echo $material
     ${FILAMENT_PATH}/matc -a opengl -a metal -a vulkan -o materials/$material.filamat materials/$material.mat || exit 1; \
 	${FILAMENT_PATH}/resgen -c -p $material -x thermion_dart/native/include/material/ materials/$material.filamat || exit 1; \

materials/linear_depth.mat

@@ -1,7 +1,7 @@
 material {
     name : LinearDepth,
     shadingModel : unlit,
-    requires : [ position, uv0 ],
+    requires : [ position ],
     shadingModel : unlit,
     doubleSided : false,
     blending: opaque,