diff -r 272c84c7c87e -r 98645c8e7704 src/gl/compiler.cpp
--- a/src/gl/compiler.cpp	Sun Feb 02 00:58:59 2020 +0200
+++ b/src/gl/compiler.cpp	Thu Feb 06 20:33:05 2020 +0200
@@ -31,6 +31,7 @@
 layout(location=0) in vec3 position;
 layout(location=1) in vec4 color;
 layout(location=2) in vec3 normal;
+layout(location=3) in vec3 id;
 out vec4 vColor;
 out vec3 vFragPos;
 out vec3 vNormal;
@@ -43,6 +44,7 @@
 const int FRAGSTYLE_BfcGreen = 1;
 const int FRAGSTYLE_BfcRed = 2;
 const int FRAGSTYLE_Random = 3;
+const int FRAGSTYLE_Id = 4;
 
 void main()
 {
@@ -56,6 +58,10 @@
 	{
 		vColor = vec4(0.9, 0.2, 0.2, 1.0);
 	}
+	else if (fragmentStyle == FRAGSTYLE_Id)
+	{
+		vColor = vec4(id, 1.0);
+	}
 	else
 	{
 		vColor = color;
@@ -75,13 +81,21 @@
 const vec3 lightPos = vec3(0.5, 0.5, 0.5);
 const vec4 lightColor = vec4(1.0, 1.0, 1.0, 1.0);
 const float ambientStrength = 0.7;
+uniform bool useLighting;
 
 void main()
 {
-	vec4 ambient = ambientStrength * lightColor;
-	vec3 lightDirection = normalize(lightPos - vFragPos);
-	vec4 diffuse = max(dot(vNormal, lightDirection), 0.0) * lightColor;
-	fColor = (ambient + diffuse) * vColor;
+	if (useLighting)
+	{
+		vec4 ambient = ambientStrength * lightColor;
+		vec3 lightDirection = normalize(lightPos - vFragPos);
+		vec4 diffuse = max(dot(vNormal, lightDirection), 0.0) * lightColor;
+		fColor = (ambient + diffuse) * vColor;
+	}
+	else
+	{
+		fColor = vColor;
+	}
 }
 )";
 
@@ -131,10 +145,12 @@
 			object.program->enableAttributeArray(0);
 			object.program->enableAttributeArray(1);
 			object.program->enableAttributeArray(2);
+			object.program->enableAttributeArray(3);
 			constexpr int stride = sizeof(gl::Vertex);
 			object.program->setAttributeBuffer(0, GL_FLOAT, offsetof(gl::Vertex, position), 3, stride);
 			object.program->setAttributeBuffer(1, GL_FLOAT, offsetof(gl::Vertex, color), 4, stride);
 			object.program->setAttributeBuffer(2, GL_FLOAT, offsetof(gl::Vertex, normal), 3, stride);
+			object.program->setAttributeBuffer(3, GL_FLOAT, offsetof(gl::Vertex, id), 3, stride);
 			object.vertexArray.release();
 			object.buffer.release();
 			object.program->release();
@@ -179,15 +195,14 @@
 	return gl::ArrayClass::Lines;
 }
 
-[[maybe_unused]]
-static QColor colorFromId(ldraw::Id id)
+static glm::vec3 colorFromId(ldraw::Id id)
 {
 	// Calculate a color based from this index. This method caters for
 	// 16777216 objects. I don't think that will be exceeded anytime soon.
 	const int r = (id.value / 0x10000) % 0x100;
 	const int g = (id.value / 0x100) % 0x100;
 	const int b = id.value % 0x100;
-	return {r, g, b};
+	return {r / 255.0f, g / 255.0f, b / 255.0f};
 }
 
 void gl::Compiler::buildPolygon(
@@ -210,6 +225,7 @@
 		vertex.position = polygon.vertices[i];
 		vertex.normal = glm::normalize(glm::cross(v1 - v2, v3 - v2));
 		vertex.color = glm::vec4{color.redF(), color.greenF(), color.blueF(), color.alphaF()};
+		vertex.id = colorFromId(polygon.id);
 	}
 }