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Thread: Max usable Texture Image Units in Fragment Shader

  1. #1
    Newbie Newbie
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    Sep 2013
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    Max usable Texture Image Units in Fragment Shader

    Hi,

    i want to active and bind as much textures as possible and then just switch the sampler that uses a different unit in fragment-shader.

    I have 2 Machines:

    1. Windows 7 with Nvidia graphic card
    GL_MAX_TEXTURE_IMAGE_UNITS: 32
    GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS: 192
    On this machine I can (only) use 32 Texture Image Units.

    2. Windows 7 and Arch-Linux with ATI graphic card
    GL_MAX_TEXTURE_IMAGE_UNITS: 16
    GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS: 32
    On this machine I can use 32 Texture Image Units too...

    Why it's the same? On both machines I can have max 32 Units and this ist ok but I want to know how to determine that.

  2. #2
    Member Regular Contributor
    Join Date
    Jun 2013
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    495
    Quote Originally Posted by KrisZero View Post
    i want to active and bind as much textures as possible and then just switch the sampler that uses a different unit in fragment-shader.

    I have 2 Machines:

    1. Windows 7 with Nvidia graphic card
    GL_MAX_TEXTURE_IMAGE_UNITS: 32
    GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS: 192
    On this machine I can (only) use 32 Texture Image Units.

    2. Windows 7 and Arch-Linux with ATI graphic card
    GL_MAX_TEXTURE_IMAGE_UNITS: 16
    GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS: 32
    On this machine I can use 32 Texture Image Units too...

    Why it's the same? On both machines I can have max 32 Units and this ist ok but I want to know how to determine that.
    GL_MAX_TEXTURE_IMAGE_UNITS is the maximum number of texture units which can be used from the fragment shader. There are similar variables for the other shaders, e.g. GL_MAX_VERTEX_TEXTURE_IMAGE_UNITS for the vertex shader. GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS is the maximum number of texture units in total, and represents the (exclusive) upper bound for the argument to glActiveTexture().

  3. #3
    Newbie Newbie
    Join Date
    Sep 2013
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    Quote Originally Posted by GClements View Post
    GL_MAX_TEXTURE_IMAGE_UNITS is the maximum number of texture units which can be used from the fragment shader. There are similar variables for the other shaders, e.g. GL_MAX_VERTEX_TEXTURE_IMAGE_UNITS for the vertex shader. GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS is the maximum number of texture units in total, and represents the (exclusive) upper bound for the argument to glActiveTexture().
    yeah, but if GL_MAX_TEXTURE_IMAGE_UNITS is the maximum number of texture units which can be used from the fragment shader
    and it shows 16, why can I use 32 in fragment shader?

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