[android-developers] Re: GL10 access from outside of the rendering thread ...

Below is my curet uploading and use of the texture from the renderer's onDrawFrame(GL10 go) method.  I would simply like to call gl.glCompressedTexImage2D from another thread, oftentimes many milliseconds before the rendering thread is ready to be called.  I place the rendering code within a try lock block and on  other platform, I place the upload request within a lock block.  If the renderer comes along why another thread is uploading the texture, it request that the context be rendered again and returns from the request without doing anything.  When the renderer successfully enters the try lock block, then outside threads are blocked from updating the texture until the rendering thread completes it's work and releases the lock.  This is very basic and works on smoothly on 4 other platforms, but my research so far has led me to a universal answer of "you can't do this".  I imagine that I could if I wanted to kick the rendering in the realm of the NDK, but I thought I'd ask for an authoritative answer first ...

                m_textureBuffer.rewind();

                gl.glCompressedTexImage2D(  GL10.GL_TEXTURE_2D,

                                            0,

                                            GL10.GL_PALETTE8_RGBA8_OES,

                                            m_textureWidth,

                                            m_textureHeight,

                                            0,

                                            m_textureSize,

                                            m_textureBuffer);

                gl.glColor4f(   m_textureColor,

                                m_textureColor,

                                m_textureColor,

                                1);

                gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, 0, 4);

On Sunday, July 1, 2012 12:26:01 AM UTC-7, Romain Guy (Google) wrote:

Hi,

How exactly are you uploading the texture on that other platform? Are you simply doing an eglMakeCurrent() to reassign the GL context to another thread or are you using an EGLImage?

On Saturday, June 30, 2012 4:33:32 PM UTC-7, gl...@wanderfulstorybooks.com wrote:

Hello,

I am optimizing an OpenGL-based application ported from that other
major mobile OS and find that I cannot successfully access the GL
context from anything other than the rendering thread of
GLSurfaceView.  What I CAN do on other platforms is upload my single
(and large) texture to GL prior to needing to render the texture
itself.  This is a 640x480 8-bit RGB texture that takes some time to
upload to the chip and needs to be done every time I realize a new
frame of animation from the background system memory buffer.  I'm sure
you can appreciate the savings in execution time if I can perform this
upload from another thread when I have nothing left to do but wait for
GLSurfaceView's rendering thread to call me.  All is synchronized
safely as evidenced by the successful release of this software using
this very same technique on that-other-platform-that-shall-not-be
named.  Things are very smooth and zippy on that platform, but Android
currently suffers by comparison.  Is there any way to do this?


Thanks

Glenn

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