supportsFloatTextureLinear

true when GL_LINEAR filtering is valid on a 32-bit-float colour texture. RGBA32F + GL_LINEAR is texture-complete only with OES_texture_float_linear / EXT_texture_float_linear; without it the sampler returns the incomplete-texture default (0,0,0,1) (Adreno 540 / Samsung S9 hits this). Callers that allocate RGBA32F must fall back to GL_NEAREST when this is false. No engine consumer since the shadow and sightline pipelines moved to plain depth textures; retained as public capability API. Always true on desktop GL3+; Android / iOS / WebGL query at runtime.