82 lines
2.5 KiB
C++
82 lines
2.5 KiB
C++
#pragma once
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#include <plot/core/status.hpp>
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#include <plot/core/types.hpp>
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#include <plot/gl/handle.hpp>
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namespace plot::render {
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/// Per-instance payload of the line pipeline: one segment in data space. It
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/// mirrors the interleaved floats `LineBatch::data()` produces, which is why the
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/// attribute offsets in vertex_array.cpp come from `offsetof` rather than from
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/// hand-written numbers.
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struct LineInstance {
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f32 x0;
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f32 y0;
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f32 x1;
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f32 y1;
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};
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/// Per-instance payload of the text pipeline: the glyph quad's top-left corner
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/// in Rect pixels plus the glyph's atlas texel origin.
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struct TextInstance {
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f32 x;
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f32 y;
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f32 u;
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f32 v;
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};
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static_assert(sizeof(LineInstance) == 4 * sizeof(f32), "line instance must stay 4 floats");
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static_assert(sizeof(TextInstance) == 4 * sizeof(f32), "text instance must stay 4 floats");
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namespace detail {
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/// The growth half of an instance buffer, shared by both pipelines so neither
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/// duplicates the GL ownership or the "grow only when the frame needs it" rule.
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class InstanceStore {
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public:
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/// Creates the vertex buffer. Reports `ErrorCode::Unsupported` while the GL
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/// entry points are unresolved, `GLFailure` if the driver hands out no name.
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bool create(Status* st = nullptr) noexcept;
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/// Uploads `count` instances of `instance_bytes`. The store only reallocates
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/// when the frame's workload outgrows it, so steady-state frames write into
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/// the existing allocation.
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void upload(const void* data, u32 count, usize instance_bytes) noexcept;
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void bind() const noexcept { buffer_.bind(); }
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private:
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gl::Buffer buffer_;
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u32 capacity_ = 0; ///< instances the store can hold
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};
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} // namespace detail
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/// Instance buffer of the line pipeline: one `LineInstance` per segment.
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class LineBuffer {
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public:
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bool create(Status* st = nullptr) noexcept { return store_.create(st); }
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void upload(const f32* interleaved, u32 count) noexcept {
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store_.upload(interleaved, count, sizeof(LineInstance));
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}
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void bind() const noexcept { store_.bind(); }
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private:
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detail::InstanceStore store_;
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};
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/// Instance buffer of the text pipeline: one `TextInstance` per glyph.
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class TextBuffer {
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public:
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bool create(Status* st = nullptr) noexcept { return store_.create(st); }
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void upload(const f32* interleaved, u32 count) noexcept {
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store_.upload(interleaved, count, sizeof(TextInstance));
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}
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void bind() const noexcept { store_.bind(); }
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private:
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detail::InstanceStore store_;
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};
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} // namespace plot::render
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