Additional resources from the Raylib repo.

Examples/resources/shaders/glsl330/outline_hull.vs

@@ -0,0 +1,15 @@
+#version 330
+
+in vec3 vertexPosition;
+in vec3 vertexNormal;
+in vec2 vertexTexCoord;
+in vec4 vertexColor;
+
+uniform mat4 mvp;
+uniform float outlineThickness;
+
+void main() {
+    // Extrude vertex along its normal to create the hull.
+    vec3 extruded = vertexPosition + vertexNormal * outlineThickness;
+    gl_Position = mvp * vec4(extruded, 1.0);
+}