From 8f0e595e23b8665d8a5b9f67637f11e4e19d1bb6 Mon Sep 17 00:00:00 2001
From: Caleb Maclennan <caleb@alerque.com>
Date: Tue, 5 Jan 2021 12:26:50 +0300
Subject: [PATCH] fix(renderings): Avoid too-thin books from rendering
 inside-out

---
 rules/functions.mk | 1 +
 rules/rules.mk     | 4 ++--
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/rules/functions.mk b/rules/functions.mk
index 2d082fa6..ea2ea3df 100644
--- a/rules/functions.mk
+++ b/rules/functions.mk
@@ -298,6 +298,7 @@ define povray ?=
 		#declare Rand1 = seed(1234);
 		#declare Rand2 = seed(4123);
 		#declare Rand3 = seed(2134);
+		#declare MinThickness = 0.005;
 	EOF
 	sleep 1.$${RANDOM} # block parallel execution
 	while $(PGREP) povray > /dev/null; do sleep 2.$${RANDOM}; done
diff --git a/rules/rules.mk b/rules/rules.mk
index 99620f73..9de7434f 100644
--- a/rules/rules.mk
+++ b/rules/rules.mk
@@ -1149,7 +1149,7 @@ $(BOOKSCENESINC): %.inc: $$(geometryfile) %-pov-$(_front).png %-pov-$(_back).png
 		#declare CoilWidth = $(COILWIDTH);
 		#declare CoilColor = $(COILCOLOR);
 		#declare PaperWeight = $(PAPERWEIGHT);
-		#declare BookThickness = $${spinemm} / $${pagewmm} / 2;
+		#declare BookThickness = max($${spinemm} / $${pagewmm} / 2, MinThickness);
 		#declare HalfThick = BookThickness / 2;
 	EOF
 
@@ -1160,7 +1160,7 @@ $(BOOKSCENES): %-$(_3d).pov: $$(geometryfile) %.inc
 		#declare DefaultBook = "$(filter %.inc,$^)";
 		#declare Lights = $(call scale,8,2);
 		#declare BookAspect = $${pagewmm} / $${pagehmm};
-		#declare BookThickness = $${spinemm} / $${pagewmm} / 2;
+		#declare BookThickness = max($${spinemm} / $${pagewmm} / 2, MinThickness);
 		#declare HalfThick = BookThickness / 2;
 		#declare toMM = 1 / $${pagehmm};
 	EOF