47 lines
2.2 KiB
C++
47 lines
2.2 KiB
C++
#pragma once
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namespace plot::render {
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/// GLSL source of the instanced antialiased line pipeline.
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///
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/// The vertex shader takes one segment per instance (`a_p0` at location 0,
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/// `a_p1` at location 1, both with a vertex attribute divisor of 1), expands it
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/// in pixel space along its normal by `u_width * 0.5 + 1.0` pixels of AA fringe,
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/// and emits a four-vertex `GL_TRIANGLE_STRIP` quad whose corners come from
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/// `gl_VertexID` (0 and 1 are the two sides of `a_p0`, 2 and 3 of `a_p1`). It
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/// outputs `v_dist`, the signed distance from the segment axis in pixels, and
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/// `v_along`, the distance travelled from `a_p0` in pixels.
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///
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/// Uniforms: `u_scale` (vec2, data space to pixels), `u_offset` (vec2, pixels),
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/// `u_viewport` (vec2, pixels), `u_width` (float, pixels), `u_color` (vec4).
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/// `plot::Rect` is top-left origin while GL is bottom-left, so the y axis is
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/// flipped exactly once, here.
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///
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/// A degenerate segment (`a_p0 == a_p1`) keeps a finite normal and is stretched
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/// into a square mark one stroke width and fringe across, rather than
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/// collapsing to zero area and rasterising nothing — the dense path stages
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/// `min == max` buckets as exactly such segments.
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///
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/// The fragment shader discards outside the fringe and ramps alpha over the last
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/// pixel of the half width with `smoothstep`, which is what keeps a 1px trace
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/// from aliasing into dashes.
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extern const char* const kLineVS;
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extern const char* const kLineFS;
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/// GLSL source of the instanced text pipeline.
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///
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/// One glyph cell per instance: `a_pos` at location 0 is the quad's top-left
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/// corner in Rect pixels and `a_uv` at location 1 is the glyph's atlas texel
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/// origin, both with a vertex attribute divisor of 1. The quad grows by
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/// `u_px_range` pixels per cell and the fragment shader samples the
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/// single-channel `GL_R8` atlas at the nearest texel centre, so `GL_NEAREST`
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/// never lands on a cell boundary. `u_color` tints the straight alpha.
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///
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/// Uniforms: `u_viewport` (vec2, pixels), `u_px_range` (vec2, pixels per glyph
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/// cell), `u_tex_size` (vec2, atlas texels), `u_atlas` (sampler2D, unit 0),
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/// `u_color` (vec4).
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extern const char* const kTextVS;
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extern const char* const kTextFS;
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} // namespace plot::render
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