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macosopenglantialiasingmultisampling

Anti aliasing with multisampling in opengl 2.1?

I have a 2007 Macbook pro with ATI radeon X1600 graphics card. I am trying to get anti aliasing working using multisampling feature.

Using GlView , this is the information that I have at hand:

The renderer information is:

Renderer: ATI Radeon X1600 OpenGL Engine
Vendor: ATI Technologies Inc.
Memory: 128 MB
Version: 2.1 ATI-7.0.52
Device: MacBookPro2,2
Shading language version: 1.20


I checked the extension information for the arb_multisample and it says: "Promoted to core feature in OpenGL 1.3", is it then correct to assume that in my code I can simply say (as I am on Opengl 2.1):

glEnable(GL_MULTISAMPLE)

In my application code, I have a data structure, which has the following information: vertices, indices and textures which I then render using glDrawElements etc. Also all are triangular meshes.

The code looks something like this:

    (capi:define-interface stad-viewer (capi:interface)
      ((double-buffered-p :initform t :initarg :double-buffered-p :accessor double-
          buffered-p))
      (:panes 
         (canvas opengl:opengl-pane
              :configuration (list :rgba t :depth t :depth-buffer 32 :double-buffered t)
              :min-width 1440 
              :min-height 900 
              :message "Stadium demo"
              :drawing-mode :quality
              :reader canvas
              :resize-callback 'resize-stad-canvas
              :display-callback 'redisplay-stad-canvas))
      (:layouts
         (main capi:column-layout '(canvas)))
      (:default-initargs :auto-menus NIL :title "Stadium Viewer"))    


;;; enable multisampling
(opengl:gl-enable opengl:*gl-multisample*)
(opengl:gl-sample-coverage 0.70 opengl:*gl-false*)

;;; some more opengl commands....

;;; rendering meshes
(dolist (wfmesh *wfmeshes*)
   (format t " ------ PREPARING MESH ---- ~A ~% " (mesh-name wfmesh))
   (multiple-value-bind (vertices indices)
        (prepare-mesh wfmesh)
      (let* ((gl-vertices (gl-vertexes vertices))
             (gl-indices (gl-indexes indices)))
        (if *texture-ids*
          (multiple-value-bind (texture-id found)
                    (gethash (mesh-name wfmesh) *texture-ids*)
             (when found
                (opengl:gl-bind-texture opengl:*gl-texture-2d* texture-id)
                (opengl:gl-tex-coord-pointer 2 opengl:*gl-float* 0 
                                                   (gl-texels (mesh-vertices wfmesh)   
                                                        1.0 t)))))      
        (opengl:gl-vertex-pointer 3 opengl:*gl-float* 0 gl-vertices)
        (opengl:gl-draw-elements opengl:*gl-triangles* 
                                   (length indices) 
                                   opengl:*gl-unsigned-int*
                                   gl-indices))))

Also I have enabled multisampling as above. However this is what I get:

The jagged edges are clearly visible.

So my questions are:

  1. Is my understanding that multisampling is a core feature correct?
  2. Does just enabling multisampling and calling drawing code work or some more steps are required to get multisampling working?
Solution

  • Are you using a Cocoa NSOpenGLView? Because then you can just enable multisampling in Interface Builder. In any case, you must create your render context specifically with sample buffers. In any case, glEnable(GL_MULTISAMPLE) is not enough. In order to get more specific help, you need to state how you create your OpenGL window / view.