questions of rendering to texture

This topic contains 1 reply, has 2 voices, and was last updated by  Gordon 8 years, 1 month ago.

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  • #29951

    pset_chris
    Member

    Hello,
    I have 2 questions about rendering to texture of OpenGL ES 1.1.

    A.
    I find that the render result on the window surface is incorrect if
    calling eglBindTexImage after rendering something to the windows
    surface.
    I tested three cases:
    Case 1(call it after rendering to texture, the result is OK):
    1. Make current(pbuffer)
    2. Render to pbuffer
    3. Bind pbuffer and texture
    4. Make current(window surface)
    5. glClear
    6. glBindTexture(tex_id)
    7. glDrawArrays

    8. Release pbuffer from texture

    The result is Ok.

    Case 2(call it after making the main surface current, the result is OK):
    1. Make current(pbuffer)
    2. Render to pbuffer
    3. Make current(window surface)
    4. Bind pbuffer and texture
    5. glClear
    6. glBindTexture(tex_id)
    7. glDrawArrays

    8. Release pbuffer from texture

    Case 3(call it after calling glClear or rendering something and before
    rendering to the window surface with the texture maped, the result is
    incorrect):
    1. Make current(pbuffer)
    2. Render to pbuffer
    3. Make current(window surface)
    4. glClear or render something
    5. glBindTexture(tex_id)
    6. Bind pbuffer and texture
    7. glDrawArrays

    8. Release pbuffer from texture

    Why
    the final render result is not correct? Rendering to window surface
    should not affect the pbuffer surface and binding the pbuffer surface
    to a texture should not affect the content of the window surface.
    What time is the correct time to call eglBindTexImage?

    B.
    Is the eglReleaseTexImage a sync function? After the eglReleaseTexImage
    returned, has the release operation been done, or just a release
    command has been sent?

    Thank you!
    Chris

    #33456

    Gordon
    Moderator

    This is not expected behaviour – which device and OS are you seeing this on?

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