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Type: Posts; User: Xmas

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    Re: gl_VertexID alternative?

    Unfortunately an ID stream is the only possible alternative, unless your vertices are e.g. arranged as a grid so that you have a simple relation between index and position.

    GLES2 implementations...
  2. Re: Quick question about GL_MAX_VERTEX_UNIFORM_VECTORS.

    Whether they are actually packed is implementation specific (but also completely invisible to the application). However there is a packing rule (described in appendix A.7 of the GLSL ES spec) which...
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    Re: Fragment shader for detecting contour pixels

    OpenGL ES 2.0 is widely supported on Android smartphones today.

    It's certainly doable, you just sample the sprite texture several times in your fragment shader with texture coordinates adjusted...
  4. Re: Compile: "ERROR: Missing main()" but spec says linking L

    OpenGL ES 2.0 does not support linking of multiple shader objects for the same shader stage. Thus a shader object without main would be of no use.

    GLSL ES does support branching and function calls.
  5. Thread: Handedness

    by Xmas
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    Re: Handedness

    By default clip space +X is right in screen space, +Y is up, and +Z is far, actually making clip space left-handed. While you cannot change the mapping direction of the first two (negative viewport...
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    Re: When to call glEnableVertexAttribArray()

    You don't have to repeatedly call glEnableVertexAttribArray, unless you are calling any code which might disable it.


    That's because glVertexAttribPointer sets up the vertex attribute to use the...
  7. Re: Android SDK // Eclipse // OPENGL ES 2.0 -> Shader Quest

    Your fragment shader seems to be lacking a closing }. That shouldn't cause a crash, though.
  8. Re: How to read Pixel data from the MultiSampled framebuffer

    You cannot read pixel data from a multisampled framebuffer, you need to blit it to a single-sampled framebuffer first.
  9. Thread: Shader Issues

    by Xmas
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    Re: Shader Issues

    I'm curious, what platforms are these?

    The vast majority of OpenGL ES 2.0 implementations support compiling shaders from source, especially those that represent a viable market for games.
  10. Thread: EGL attribute

    by Xmas
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    Re: EGL attribute

    If the bit is not set for a specific API, it means that the implementation does not conform to the specification of the API in some way when using this EGL config.

    In which way it deviates from...
  11. Re: glClear alpha vs geometry alpha -- blending result conf

    Try to formulate what you want to achieve in terms of addition and multiplication of the RGB and alpha values, and it should quickly become clear what you need to do.

    Note that OpenGL ES 2.0 has...
  12. Re: Difference between uniform and constant vertex attribute

    Whether it's quicker to do one or the other is an implementation detail, in reality it's unlikely to make much of a difference.

    However, duplicating the colours is likely to be much faster than...
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    Re: Keeping resources on server side alive

    OpenGL (ES) resources belong to a GL context. A context is independent of any windows you might create or destroy.
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    Re: What is the meaning of a naked type?

    The grammar is not a full description of valid shader code. There are semantic rules as well.
  15. Re: Peformance for using Frame buffers and glReadPixels

    You can't make copying pixels itself faster that way, but if you are rendering multiple frames then you can avoid stalling the CPU and GPU when using glReadPixels. As GPUs operate in parallel to the...
  16. Re: VBO Test - glBufferData vs glBufferSubData vs glMapBuffe

    Are you replacing the entire buffer contents or just a subset?
  17. Re: Specification for Enable(), Disable() functions?

    It probably would be easiest to refer to the reference pages:
    http://www.khronos.org/opengles/sdk/docs/man/
  18. Re: OpenGL ES 2.0 shaders off-screen blend and color convers

    You need a vertex shader.
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    Re: Blending Bitmap Fonts, Retain Antialiasing?

    What texture format are you using?
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    Re: How does the Current shader affect glClear ?

    The current shader does not affect glClear.
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    Re: Problem with glGetTexImage

    glGetTexImage is not part of either OpenGL ES 1.x or 2.0 core specifications. Are you using an extension?
  22. Thread: ES2 and VBOs

    by Xmas
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    Re: ES2 and VBOs

    You can and should use VBOs in OpenGL ES 2.0, too. The commands to handle buffer objects (e.g. glBindBuffer, glBufferData) are available in ES2.0, you just use the generic glVertexAttribPointer...
  23. Re: glteximage2D with odd width and height possible or not?

    OpenGL ES 2.0 supports non-power-of-two textures, but with restrictions (no mipmaps, wrap mode must be GL_CLAMP_TO_EDGE). If OES_texture_npot is supported, those restrictions no longer apply.
    ...
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    Re: Problem when moving object in Z coord...

    gl_Position is the position of the vertex in homogeneous clip space. Its Z component is only used for clipping against the near and far planes as well as for the depth test. It does not affect the...
  25. Thread: GL_FLOAT

    by Xmas
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    Re: GL_FLOAT

    What OpenGL ES implementation are you using? If it only supports the Common Lite profile, you have to use fixed point data, floats are not supported on Common Lite.
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