Function image_sampler_enabled 

pub fn image_sampler_enabled() -> bool

Whether Medium-quality atlas images are filtered through the hardware sampler — on unless FRUST_ENGINE_IMAGE_SAMPLER=0 (or false) says otherwise. Cached: read once per process.

On, the renderer compiles the image-sampling strip programs from their IMAGE_SAMPLER specialisation (see crate::gpu::shader_src): a bilinear atlas image is read with one filtered textureSampleLevel instead of four textureLoad taps, at the filtering precision of the hardware rather than in full f32 — within the image tolerance the CPU-oracle gate already holds, at about three quarters of the GPU cost on a magnified image stream. The kill switch (0) compiles the manual family instead: no strip layout declares a sampler and every program is the four-tap one — pixel for pixel what the engine drew before the sampler existed — which is the escape hatch for a driver that filters wrongly, and the off-arm of every before/after measurement of it. EngineRenderer::with_image_sampler is its programmatic counterpart.