SB-003-RENDER_SYSTEM.md (P0, 369 lines)

• PVR2-based text rendering system
• Components: Font Manager, Screen Manager, Texture Atlas, PVR2 Renderer
• Data structures: d3tui_glyph_t (metrics + tex coords), d3tui_font_t (name, size, texture ptr, glyph array), d3tui_render_ctx_t (font, colors, cursor, cell size, dirty flag)
• Public API: font_load/free, render_create/destroy, set_font/colors/cell_size, render_char/text/move_cursor, flush
• PVR2 texture formats: ARGB1555 (fonts), RGB565 (backgrounds), ARGB4444 (high-quality)
• Font texture atlas: 16x16 grid of 256 chars, typically 256x256, ARGB1555, 1-pixel padding
• Rendering pipeline: pvr_scene_begin → polygon headers → submit quads per char → cursor → pvr_scene_finish
• Custom .d3f binary font format defined (magic “D3TF”, version 1, glyph table + texture data)
• Font conversion tool d3tui-fontconv (Python, Pillow) to convert TTF/OTF → .d3f
• Optimizations: batch rendering, dirty rectangles, texture atlases, PVR2 Store Queue (SQ) for vertex submission