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Re: [Public WebGL] FF generating: WebGL: bendFunc: dfactor: invaldi enum value 0x201



Title: Re: [Public WebGL] FF generating: WebGL: bendFunc: dfactor
At 9:30 PM -0600 3/10/11, Patrick Baggett wrote:
This is invalid OpenGL/ES. See http://www.opengl.org/sdk/docs/man/xhtml/glBlendFunc.xml

The second argument needs to be a destination factor. What are you trying to achieve?

Thanks for responding Patrick,

I'm debugging what the SceneJS framework renders.

Lindsay Kay is the author so he'll probably know more about why he's calling blendFunc this way.

Perhaps it's just a mistake -- I'm still learning how OpenGL works.


On Thu, Mar 10, 2011 at 8:34 PM, Stephen Bannasch <stephen.bannasch@deanbrook.org> wrote:

When I set webgl.berbose to true in FF/Minefield I'm getting this error:

 WebGL: bendFunc: dfactor: invaldi enum value 0x201

when executing:
 gl.blendFunc(gl.ONE_MINUS_SRC_ALPHA, gl.LESS)

You can see this happen on this page:

 http://scenejs.org/dist/curr/extr/examples/hello-teapot/index.html

The spec states LESS is not supported:

 http://www.khronos.org/registry/webgl/specs/latest/#CONSTANT_COLOR_BLEND

 /* AlphaFunction (not supported in ES20) */
 /*      NEVER */
 /*      LESS */
 /*      EQUAL */
 /*      LEQUAL */
 /*      GREATER */
 /*      NOTEQUAL */
 /*      GEQUAL */
 /*      ALWAYS */

 /* BlendingFactorDest */
 const GLenum ZERO                           = 0;
 const GLenum ONE                            = 1;
 const GLenum SRC_COLOR                     = 0x0300;
 const GLenum ONE_MINUS_SRC_COLOR            = 0x0301;
 const GLenum SRC_ALPHA                     = 0x0302;
 const GLenum ONE_MINUS_SRC_ALPHA            = 0x0303;
 const GLenum DST_ALPHA                     = 0x0304;
 const GLenum ONE_MINUS_DST_ALPHA            = 0x0305;

Is this operation supported?
I don't see a way to turn on something equivalent to webgl.verbose in Safari/WebKit or Chrome but I haven't seen those errors/warnings running in these browsers.