From 26dedb83988154d3f6af3bcbba1a3bb9abe770e9 Mon Sep 17 00:00:00 2001
From: Elliot Cameron <eacameron@gmail.com>
Date: Thu, 7 Jan 2021 23:46:47 -0500
Subject: [PATCH] vtk: use system png

VTK doesn't seem produce png symbols on aarch64. We could probably
figure out how to fix that but we can also just tell it to use the
libpng we already have, which already works on aarch64.
---
 pkgs/development/libraries/vtk/generic.nix | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/pkgs/development/libraries/vtk/generic.nix b/pkgs/development/libraries/vtk/generic.nix
index 7bfd8d9fcff..2cb0fe33d52 100644
--- a/pkgs/development/libraries/vtk/generic.nix
+++ b/pkgs/development/libraries/vtk/generic.nix
@@ -1,5 +1,5 @@
 { majorVersion, minorVersion, sourceSha256, patchesToFetch ? [] }:
-{ stdenv, lib, fetchurl, cmake, libGLU, libGL, libX11, xorgproto, libXt, libtiff
+{ stdenv, lib, fetchurl, cmake, libGLU, libGL, libX11, xorgproto, libXt, libpng, libtiff
 , fetchpatch
 , enableQt ? false, wrapQtAppsHook, qtbase, qtx11extras, qttools
 , enablePython ? false, pythonInterpreter ? throw "vtk: Python support requested, but no python interpreter was given."
@@ -24,7 +24,7 @@ in stdenv.mkDerivation rec {
 
   nativeBuildInputs = [ cmake ];
 
-  buildInputs = [ libtiff ]
+  buildInputs = [ libpng libtiff ]
     ++ optionals enableQt [ qtbase qtx11extras qttools ]
     ++ optionals stdenv.isLinux [
       libGLU
@@ -65,6 +65,7 @@ in stdenv.mkDerivation rec {
   cmakeFlags = [
     "-DCMAKE_C_FLAGS=-fPIC"
     "-DCMAKE_CXX_FLAGS=-fPIC"
+    "-DVTK_USE_SYSTEM_PNG=ON"
     "-DVTK_USE_SYSTEM_TIFF=1"
     "-DOPENGL_INCLUDE_DIR=${libGL}/include"
     "-DCMAKE_INSTALL_LIBDIR=lib"