134 lines
6.0 KiB
C++
134 lines
6.0 KiB
C++
#pragma once
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#include <mbgl/shaders/line_layer_ubo.hpp>
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#include <mbgl/shaders/shader_source.hpp>
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#include <mbgl/shaders/mtl/common.hpp>
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#include <mbgl/shaders/mtl/shader_program.hpp>
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namespace mbgl {
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namespace shaders {
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template <>
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struct ShaderSource<BuiltIn::LineGradientShader, gfx::Backend::Type::Metal> {
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static constexpr auto name = "LineGradientShader";
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static constexpr auto vertexMainFunction = "vertexMain";
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static constexpr auto fragmentMainFunction = "fragmentMain";
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static constexpr auto hasPermutations = false;
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static const std::array<AttributeInfo, 7> attributes;
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static const std::array<UniformBlockInfo, 5> uniforms;
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static const std::array<TextureInfo, 1> textures;
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static constexpr auto source = R"(
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struct VertexStage {
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short2 pos_normal [[attribute(0)]];
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uchar4 data [[attribute(1)]];
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float2 blur [[attribute(2)]];
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float2 opacity [[attribute(3)]];
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float2 gapwidth [[attribute(4)]];
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float2 offset [[attribute(5)]];
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float2 width [[attribute(6)]];
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};
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struct FragmentStage {
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float4 position [[position, invariant]];
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float2 width2;
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float2 gapwidth;
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float2 normal;
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float gamma_scale;
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float blur;
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float opacity;
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float lineprogress;
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};
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FragmentStage vertex vertexMain(thread const VertexStage vertx [[stage_in]],
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device const LineGradientUBO& line [[buffer(7)]],
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device const LineGradientPropertiesUBO& props [[buffer(8)]],
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device const LineGradientInterpolationUBO& interp [[buffer(9)]],
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device const LinePermutationUBO& permutation [[buffer(10)]],
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device const ExpressionInputsUBO& expr [[buffer(11)]]) {
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const auto blur = valueFor(permutation.blur, props.blur, vertx.blur, interp.blur_t, expr);
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const auto opacity = valueFor(permutation.opacity, props.opacity, vertx.opacity, interp.opacity_t, expr);
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const auto gapwidth = valueFor(permutation.gapwidth, props.gapwidth, vertx.gapwidth, interp.gapwidth_t, expr) / 2;
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const auto offset = valueFor(permutation.offset, props.offset, vertx.offset, interp.offset_t, expr) * -1;
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const auto width = valueFor(permutation.width, props.width, vertx.width, interp.width_t, expr);
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// the distance over which the line edge fades out.
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// Retina devices need a smaller distance to avoid aliasing.
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const float ANTIALIASING = 1.0 / line.device_pixel_ratio / 2.0;
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const float2 a_extrude = float2(vertx.data.xy) - 128.0;
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const float a_direction = fmod(float(vertx.data.z), 4.0) - 1.0;
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const float v_lineprogress = (floor(float(vertx.data.z) / 4.0) + vertx.data.w * 64.0) * 2.0 / MAX_LINE_DISTANCE;
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const float2 pos = floor(float2(vertx.pos_normal) * 0.5);
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// x is 1 if it's a round cap, 0 otherwise
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// y is 1 if the normal points up, and -1 if it points down
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// We store these in the least significant bit of a_pos_normal
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const float2 normal = float2(vertx.pos_normal) - 2.0 * pos;
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const float2 v_normal = float2(normal.x, normal.y * 2.0 - 1.0);
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const float halfwidth = width / 2.0;
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const float inset = gapwidth + (gapwidth > 0.0 ? ANTIALIASING : 0.0);
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const float outset = gapwidth + halfwidth * (gapwidth > 0.0 ? 2.0 : 1.0) + (halfwidth == 0.0 ? 0.0 : ANTIALIASING);
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// Scale the extrusion vector down to a normal and then up by the line width of this vertex.
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const float2 dist = outset * a_extrude * LINE_NORMAL_SCALE;
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// Calculate the offset when drawing a line that is to the side of the actual line.
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// We do this by creating a vector that points towards the extrude, but rotate
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// it when we're drawing round end points (a_direction = -1 or 1) since their
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// extrude vector points in another direction.
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const float u = 0.5 * a_direction;
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const float t = 1.0 - abs(u);
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const float2 offset2 = offset * a_extrude * LINE_NORMAL_SCALE * v_normal.y * float2x2(t, -u, u, t);
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const float4 projected_extrude = line.matrix * float4(dist / line.ratio, 0.0, 0.0);
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const float4 position = line.matrix * float4(pos + offset2 / line.ratio, 0.0, 1.0) + projected_extrude;
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// calculate how much the perspective view squishes or stretches the extrude
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const float extrude_length_without_perspective = length(dist);
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const float extrude_length_with_perspective = length(projected_extrude.xy / position.w * line.units_to_pixels);
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return {
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.position = position,
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.width2 = float2(outset, inset),
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.gapwidth = gapwidth,
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.normal = v_normal,
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.gamma_scale = extrude_length_without_perspective / extrude_length_with_perspective,
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.blur = blur,
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.opacity = opacity,
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.lineprogress = v_lineprogress,
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};
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}
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half4 fragment fragmentMain(FragmentStage in [[stage_in]],
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device const LineGradientUBO& line [[buffer(7)]],
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device const LinePermutationUBO& permutation [[buffer(10)]],
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texture2d<float, access::sample> gradientTexture [[texture(0)]]) {
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if (permutation.overdrawInspector) {
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return half4(1.0);
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}
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// Calculate the distance of the pixel from the line in pixels.
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const float dist = length(in.normal) * in.width2.x;
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// Calculate the antialiasing fade factor. This is either when fading in the
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// line in case of an offset line (v_width2.y) or when fading out (v_width2.x)
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const float blur2 = (in.blur + 1.0 / line.device_pixel_ratio) * in.gamma_scale;
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const float alpha = clamp(min(dist - (in.width2.y - blur2), in.width2.x - dist) / blur2, 0.0, 1.0);
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// For gradient lines, v_lineprogress is the ratio along the entire line,
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// scaled to [0, 2^15), and the gradient ramp is stored in a texture.
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constexpr sampler sampler2d(coord::normalized, filter::linear);
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const float4 color = gradientTexture.sample(sampler2d, float2(in.lineprogress, 0.5));
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return half4(color * (alpha * in.opacity));
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}
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)";
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};
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} // namespace shaders
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} // namespace mbgl
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