use program pipelines instead

vis/shaders/ortho.vs.glsl

@@ -1,5 +1,9 @@
 #version 430
 
+out gl_PerVertex {
+    vec4 gl_Position;
+};
+
 layout(location=0) uniform mat4 proj;
 layout(location=1) uniform mat4 view;
 
@@ -8,8 +12,6 @@ layout(location=0) in vec4 pos;
 out vec4 vpos;
 
 void main() {
-    int i = gl_VertexID;
     vpos = view * pos;
     gl_Position = proj * vec4(vpos.xyz / (1), 1);
-    gl_PointSize = 5;
 }