74 lines
3.0 KiB
C++
74 lines
3.0 KiB
C++
#pragma once
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#include <plot/core/color.hpp>
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#include <plot/core/status.hpp>
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#include <plot/gl/handle.hpp>
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#include <plot/math/vec2.hpp>
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namespace plot::render {
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/// Linked line program and its uniform surface.
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///
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/// It owns the `plot::gl::Program` and knows the GLSL pair (shaders.hpp), so no
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/// caller spells out a uniform name that could drift from the shader. Creating
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/// it propagates what the GL layer reports: `ErrorCode::Unsupported` while
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/// `plot::gl::available()` is false, `GLFailure` plus the driver's log when the
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/// GLSL does not compile or link.
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class LineProgram {
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public:
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bool create(Status* st = nullptr) noexcept;
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bool valid() const noexcept { return program_.id() != 0; }
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void bind() const noexcept { program_.use(); }
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/// `u_scale`: data space to pixels.
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void set_scale(Vec2 data_to_px) const noexcept;
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/// `u_offset`: pixel offset added after `set_scale`.
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void set_offset(Vec2 px) const noexcept;
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/// `u_viewport`: render target size in pixels.
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void set_viewport(Vec2 px) const noexcept;
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/// `u_width`: stroke width in pixels.
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void set_width(f32 px) const noexcept;
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/// `u_dash`: the dash pattern in pixels -- `x` the ink length, `y` the gap, and a
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/// non-positive `y` (the default a caller passes) means **solid**. It is a fragment-shader
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/// discard on the interpolated `v_along`, so it costs no geometry, and it is the one uniform
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/// that distinguishes the crosshair's stroke from every other line in the library.
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void set_dash(Vec2 on_off) const noexcept;
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/// `u_color`: stroke colour, alpha included.
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void set_color(Color color) const noexcept;
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private:
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gl::Program program_;
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};
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/// Linked text program and its uniform surface. It fails exactly the way
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/// `LineProgram::create()` does, propagating `Unsupported` and `GLFailure`.
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///
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/// `create()` also points the `u_atlas` sampler at texture unit 0, which is the
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/// unit `plot::gl::Texture::bind()` defaults to, and leaves this program bound.
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/// The atlas itself stays with the caller, who owns its lifetime.
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class TextProgram {
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public:
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bool create(Status* st = nullptr) noexcept;
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bool valid() const noexcept { return program_.id() != 0; }
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void bind() const noexcept { program_.use(); }
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/// `u_viewport`: render target size in pixels.
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void set_viewport(Vec2 px) const noexcept;
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/// `u_px_range`: the glyph cell's size on screen, in pixels (width and
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/// height -- a cell need not be square).
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void set_px_range(Vec2 px) const noexcept;
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/// `u_glyph_uv`: the glyph cell's size in the atlas, normalised. It is the
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/// rect every staged glyph is read through, so it is one size per draw -- and
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/// it is the *backend's* (`TextBackend::cell_uv`), never a glyph's, because a
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/// draw may stage glyphs whose origins differ even when their size cannot.
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void set_glyph_uv(Vec2 uv) const noexcept;
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/// `u_tex_size`: atlas size in texels.
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void set_texture_size(Vec2 texels) const noexcept;
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/// `u_color`: tint colour, alpha included.
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void set_color(Color color) const noexcept;
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private:
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gl::Program program_;
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};
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} // namespace plot::render
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