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c069890ac7
Second stage of GL 3.0 transform feedback: captured draws now write real data. - Device setup enables the VK_EXT_transform_feedback feature when present and loads the bind/begin/end entry points. - Captured draws compile an XfbCapture program variant whose last vertex-processing stage gets XfbBuffer/XfbStride/Offset decorations from the program's resolved varyings (a new spirv-opt pass). A captured gl_Position is mirrored into a dedicated output written before every OpReturn - or before every OpEmitVertex in a geometry stage - ahead of the position fixup, so the captured value is the shader's own pre-remap position. - DrawArrays/DrawElements wrap the draw in Begin/EndTransformFeedbackEXT; a small counter buffer resumes the append position across draws within one glBeginTransformFeedback (fresh Begin starts at the bound offsets). - Capture targets are promoted to persistently-mapped host-coherent GPU storage (persistent-map storage now also carries the transform feedback usage), so MapBuffer/GetBufferSubData read the captured bytes after the fence wait glEndTransformFeedback now performs. - Draw-mode/feedback-mode validation defers to the geometry shader's output primitive when one is present, and glGetBooleanv reports GL_TRANSFORM_FEEDBACK_ACTIVE/PAUSED so dEQP's per-case state reset can unwind an active capture. KHR-GL33: transform_feedback capture_vertex_*/capture_geometry_*/ discard_*/draw_xfb and clip_distance.coverage now pass; queries (PRIMITIVES_WRITTEN) and gl_ClipDistance capture remain.