magnum/doc/troubleshooting.dox

/*
    This file is part of Magnum.

    Copyright © 2010, 2011, 2012, 2013 Vladimír Vondruš <mosra@centrum.cz>

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*/

namespace Magnum {
/** @page troubleshooting Troubleshooting

@brief Various tricks to overcome to common building and rendering issues.

@section troubleshooting-building Building issues

If your project suddenly stops building after %Magnum upgrade, check these
things:

-   If the building fails on CMake step, be sure that you have up-to-date
    `FindCorrade.cmake`, `FindMagnum.cmake` and other CMake modules in your
    project (`FindSDL2.cmake`). They are contained in `modules/` directory of
    %Magnum sources (and sources of other projects) also are installed into
    `share/cmake/Magnum`.
-   In some cases when the changes done to build system are too drastic,
    recreating the build dir or clearing CMake cache is needed, but this is
    a very rare occasion.
-   The library is constantly evolving, thus some API might get deprecated over
    time (and later removed). Either build the libraries with `BUILD_DEPRECATED`
    or switch to non-deprecated features. See @ref building for more
    information.

@section troubleshooting-rendering Rendering issues

If you are experiencing so-called "black screen of death", you might want to
try these things:

-   Verify that @ref Renderer::error() "no OpenGL error was emitted".
-   Check that you use only extensions that are
    @ref Context::isExtensionSupported() "available on your system".
-   Check that you didn't exceed any implementation-defined limit (see
    `magnum-info` output for list of all of them).
-   Enable @ref DebugMessage "debug output" to see more detailed errors,
    warnings and performance hints.
-   If using framebuffer objects, @ref Framebuffer::checkStatus() "check that they are complete".
-   Change @ref Renderer::setClearColor() "framebuffer clear color" to
    something else than black to verify that at least something is drawn.
-   If nothing is drawn, use @ref PrimitiveQuery to check that at least some
    primitives were generated. Use @ref SampleQuery to check whether fragments
    were drawn.
-   Verify that the mesh is properly set up -- nonzero vertex/index count,
    matching type in buffer and @ref Mesh::addVertexBuffer() "vertex specification",
    properly set up @ref Mesh::setIndexBuffer() "index buffer" and index count
    for indexed mesh. If you specified index range, be sure that all indices
    fall into it, otherwise you would get undefined behavior.
-   Try disabling @ref Renderer::Feature::DepthTest "depth test",
    @ref Renderer::Feature::FaceCulling "face culling" and other renderer
    features that might affect the fragments.
-   Verify that your projection and transformation matrix is properly set up --
    try drawing points instead of triangles, to see if they are at least at
    proper places.
-   @ref AbstractShaderProgram::validate() "Validate the shader", check that
    all used uniforms and attributes have proper locations. Try reducing it
    until it is able to draw something, possibly also with some simpler mesh.

@section troubleshooting-debugging Debugging rendering

-   Enable @ref DebugMessage "debug output" to see additional performance hints
    and implementation-dependent information.
-   Use @ref TimeQuery to find hot spots in the rendering code.
-   @ref DebugMessage::insert() "Mark relevant parts of code" to find them
    easier in the debugger.
-   Use ApiTrace to trace the program call by call, verify buffer and texture
    contents, vertex binding and count of generated primitives, rendered
    fragments and time spent in various calls.

*/
}