88 lines
3.4 KiB
C++
88 lines
3.4 KiB
C++
#pragma once
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#include <plot/core/types.hpp>
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#include <plot/math/vec2.hpp>
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#include <plot/render/bitmap_font.hpp>
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#include <vector>
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namespace plot::render {
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/// CPU-side staging for one instanced-AA line draw call.
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///
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/// `begin()` starts a frame and `clear()` empties the batch; neither releases
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/// the store, and both leave capacity alone so a steady-state frame re-uses the
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/// previous allocation instead of reallocating per frame. The renderer re-uses
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/// one batch for the whole run and uploads `data()` once per frame.
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///
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/// The payload is interleaved `x0,y0,x1,y1` per segment — exactly the
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/// per-instance attribute layout the line shader declares (see buffer.hpp and
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/// shaders.hpp), so the intersection of `data()` with an `f32` span can be
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/// uploaded verbatim.
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class LineBatch {
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public:
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/// Starts a frame: empties the batch, keeps its capacity.
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void begin() noexcept;
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/// Same as `begin()`, so the render loop can read as begin/stage/draw.
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void clear() noexcept;
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/// Stages one segment: one instance, two quad corners per end.
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void add_segment(Vec2 a, Vec2 b);
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/// Stages `n - 1` segments joining consecutive points. A null pointer or
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/// fewer than two points stages nothing.
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void add_polyline(const Vec2* pts, u32 n);
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/// Segments staged so far, one instance each.
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u32 segment_count() const noexcept { return static_cast<u32>(v_.size() / 4u); }
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/// Vertices the pipeline will rasterise: two per staged segment.
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u32 vertex_count() const noexcept { return segment_count() * 2u; }
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/// Interleaved `x0,y0,x1,y1`, four floats per staged segment.
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const std::vector<f32>& data() const noexcept { return v_; }
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private:
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std::vector<f32> v_;
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};
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/// CPU-side staging for one instanced text draw call.
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///
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/// Like `LineBatch` it keeps its capacity across frames. Each staged glyph is
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/// one instance: the glyph quad's top-left corner in pixels, top-left origin
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/// like `plot::Rect`, plus the glyph's atlas texel origin, interleaved as
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/// `x,y,u,v` — the layout the text shader declares (see buffer.hpp).
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class TextBatch {
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public:
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/// Starts a frame: empties the batch, keeps its capacity.
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void begin() noexcept;
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/// Same as `begin()`.
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void clear() noexcept;
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/// Stages one glyph cell at `pos_px` (its top-left corner), reading the cell
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/// from `slot` in the font atlas (see `BitmapFont::atlas_origin`). `slot`
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/// indexes the atlas, not a codepoint.
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void add_glyph(Vec2 pos_px, u32 slot);
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/// Stages every codepoint of `utf8` and returns the pen past the last glyph,
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/// so the run is exactly `font.measure(utf8) * px_per_cell /
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/// BitmapFont::kGlyphPx` pixels wide — the width the draw covers when it is
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/// told the same cell size as `u_px_range`.
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///
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/// `px_per_cell` is the on-screen size of one glyph cell: pass
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/// `BitmapFont::kGlyphPx` for 1:1 text, and anything else to scale the run.
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/// The glyph quad itself is sized by the shader's `u_px_range`, which must be
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/// the same value. A null or empty string stages nothing and returns `pen_px`.
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Vec2 add_text(Vec2 pen_px, const char* utf8, const BitmapFont& font,
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f32 px_per_cell = static_cast<f32>(BitmapFont::kGlyphPx));
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/// Glyphs staged so far, one instance each.
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u32 glyph_count() const noexcept { return static_cast<u32>(v_.size() / 4u); }
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/// Interleaved `x,y,u,v`, four floats per staged glyph.
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const std::vector<f32>& data() const noexcept { return v_; }
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private:
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std::vector<f32> v_;
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};
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} // namespace plot::render
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