Steven used multisampled textures from the beginning, but this caused
incompatibilities: https://github.com/Thinkofname/steven/issues/74.
Subsequently fixed by increasing the number of samples, but increasing
it beyond the limit caused more incompatibilities, so it was clamped to
the maximum samples reported as supported by the system.
Fast-forward to now, as part of adding WebGL support (#446), the use of
multisampled textures via the glTexImage2DMultisample() call is
unsupported on this platform. Replace the following:
* glTexImage2DMultisample -> glTexImage2D
* TEXTURE_2D_MULTISAMPLE -> TEXTURE_2D
* sampler2DMS -> sampler2D
This disables the custom multisampling anti-aliasing algorithm (MSAA)
implemented in the chunk fragment shader, increasing compatibility:
* Update to glow release, remove image_2d_sample()
MSAA may be added back at a later date using multisampled renderbuffers
instead, see #442.
Part of fixing graphical rendering bugs: https://github.com/iceiix/steven/issues/25
Corrupted graphics on AMD video cards: https://github.com/Thinkofname/steven/issues/74
The previous workaround set NUM_SAMPLES to 2, but this added an extra texel fetch. Setting to 1 reproduces the 16px blue striped unexpected behavior. Setting to 0 samples avoids the extra fetch and the striping.
This is allowed per http://docs.gl/gl3/glTexImage2DMultisample:
> samples specifies the number of samples in the image and must be in the range zero to GL_MAX_SAMPLES - 1.
iceiix