diff -r 3c10f0e2fbe0 -r d56cc7387dad src/gl/compiler.cpp
--- a/src/gl/compiler.cpp	Fri Feb 07 01:58:34 2020 +0200
+++ b/src/gl/compiler.cpp	Fri Feb 07 02:01:21 2020 +0200
@@ -31,8 +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 idColor;
-layout(location=4) in int id;
+layout(location=3) in int id;
 out vec4 vColor;
 out vec3 vFragPos;
 out vec3 vNormal;
@@ -55,7 +54,13 @@
 	vNormal = normalize(normalMatrix * normal);
 	if (fragmentStyle == FRAGSTYLE_Id)
 	{
-		vColor = vec4(idColor, 1.0);
+		/* Calculate a color based from this index. This method caters for
+		 * 16777216 objects. I don't think that will be exceeded anytime soon.
+		 */
+		int r = (id / 0x10000) % 0x100;
+		int g = (id / 0x100) % 0x100;
+		int b = id % 0x100;
+		vColor = vec4(r / 255.0, g / 255.0, b / 255.0, 1.0);
 	}
 	else
 	{
@@ -153,7 +158,7 @@
 			object.buffer.setUsagePattern(QOpenGLBuffer::DynamicDraw);
 			object.vertexArray.create();
 			object.vertexArray.bind();
-			for (int k : {0, 1, 2, 3, 4})
+			for (int k : {0, 1, 2, 3})
 			{
 				object.program->enableAttributeArray(k);
 			}
@@ -161,8 +166,7 @@
 			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, idColor), 3, stride);
-			glVertexAttribIPointer(4, 1, GL_INT, stride, (void*)offsetof(gl::Vertex, id));
+			glVertexAttribIPointer(3, 1, GL_INT, stride, (void*)offsetof(gl::Vertex, id));
 			object.vertexArray.release();
 			object.buffer.release();
 			object.program->release();
@@ -207,16 +211,6 @@
 	return gl::ArrayClass::Lines;
 }
 
-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 / 255.0f, g / 255.0f, b / 255.0f};
-}
-
 ldraw::Id gl::Compiler::idFromColor(const std::array<GLbyte, 3>& data)
 {
 	return {data[0] * std::int32_t{0x10000} + data[1] * std::int32_t{0x100} + data[2]};
@@ -242,7 +236,6 @@
 		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.idColor = colorFromId(polygon.id);
 		vertex.id = polygon.id.value;
 	}
 }