JVM crash while drawing a 0 vertex count mesh

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1

On my MacBook, JVM crashes when BitmapText with text “” (length 0).

I don’t know what is the best solution for this bug.

  1. Fix for the BitmapText class only?
  2. Don’t render Mesh with vertex count 0



    I suggest the second solution.

    [patch]

    Index: src/jogl/com/jme3/renderer/jogl/JoglRenderer.java

    ===================================================================

    — src/jogl/com/jme3/renderer/jogl/JoglRenderer.java (revision 6467)

    +++ src/jogl/com/jme3/renderer/jogl/JoglRenderer.java (working copy)

    @@ -1066,6 +1066,8 @@

    }



    public void renderMesh(Mesh mesh, int lod, int count) {
  •    if (mesh.getVertexCount() == 0)<br />

  •        return;<br />

if (context.pointSize != mesh.getPointSize()) {

gl.glPointSize(mesh.getPointSize());

context.pointSize = mesh.getPointSize();

Index: src/lwjgl-ogl/com/jme3/renderer/lwjgl/LwjglRenderer.java

===================================================================

— src/lwjgl-ogl/com/jme3/renderer/lwjgl/LwjglRenderer.java (revision 6467)

+++ src/lwjgl-ogl/com/jme3/renderer/lwjgl/LwjglRenderer.java (working copy)

@@ -2160,6 +2160,8 @@

}



public void renderMesh(Mesh mesh, int lod, int count) {

  •    if (mesh.getVertexCount() == 0)<br />

  •        return;<br />

if (context.pointSize != mesh.getPointSize()) {

glPointSize(mesh.getPointSize());

context.pointSize = mesh.getPointSize();

[/patch]

2

yeah the second solution looks better to me, since the mesh won’t be sent to the gpu.

3

Second solution sound better yes, since there are rare circumstances in other parts of the engine where you have a null mesh as well ( just say particles, morphing models and hard lod here)

4

Yes I agree with the 2nd solution

5

Thank you for the answers.

Committed rev. 6487

6

Sorry for the bump, but I’ve found that creating an empty mesh and rendering it will bypass this check where an empty mesh have a vertex count of -1. Either 1) a new empty mesh should have a vertex count of 0 ( which then willnot decrease the overall vertex count statistic) or 2 ) the renderMesh(Mesh mesh, int lod, int count) implementation should skip any vertex count <=0.
Form me the first solution is the better.
This caused me troubles where rendering an empty mesh resulted in a org.lwjgl.opengl.OpenGLException: Invalid value (1281)

7

Are you using 3.0 or the new 3.1? The latter has some fix related to this already… don’t know if it covers your issue but something was changed here.

8

Well there’s a somewhat related issue here:

9

How about this for both issues:

make the initial value -1.
Then in the update change that to 0 or higher depending on the actual mesh.
If getVertexCount/( is called and -1 is still present throw a hard exeption that the mesh is not properly updated.

This comes at the cost of an additional if however, but i guess the jvm would be intelligent enough to discard it quite soon as the field rarly changes at all.

10

To solve my problem I changed the value from -1 to 0 through reflexion. I don’t think that updating the count will work since you must have a Position buffer to update the value :

public void updateCounts(){
    [...]
    VertexBuffer pb = getBuffer(Type.Position);
    VertexBuffer ib = getBuffer(Type.Index);
    if (pb != null){
        vertCount = pb.getData().limit() / pb.getNumComponents(); <-- THIS WILL NEVER BE UPDATED IF THERE IS NO POSITION BUFFER
    }
    if (ib != null){
        elementCount = computeNumElements(ib.getData().limit());
    }else{
        elementCount = computeNumElements(vertCount);
    }
}

And to reply to @pspeed, i’m using 3.0 from the maven repo. However, from what I saw in the 3.1 Master, the problem might still be present.