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implement line pattern shader for Metal (#1669)

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
This commit is contained in:
Wei Chen
2023-09-25 10:25:52 +08:00
committed by GitHub
parent d663e6e1f4
commit 4768a85798
3 changed files with 215 additions and 1 deletions
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213
include/mbgl/shaders/mtl/line.hpp
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@@ -137,5 +137,218 @@ half4 fragment fragmentMain(FragmentStage in [[stage_in]],
)";
};
template <>
struct ShaderSource<BuiltIn::LinePatternShader, gfx::Backend::Type::Metal> {
static constexpr auto name = "LinePatternShader";
static constexpr auto vertexMainFunction = "vertexMain";
static constexpr auto fragmentMainFunction = "fragmentMain";
static constexpr AttributeInfo attributes[] = {
{0, gfx::AttributeDataType::Short2, 1, "a_pos_normal"},
{1, gfx::AttributeDataType::UByte4, 1, "a_data"},
{2, gfx::AttributeDataType::Float2, 1, "a_blur"},
{3, gfx::AttributeDataType::Float2, 1, "a_opacity"},
{4, gfx::AttributeDataType::Float2, 1, "a_gapwidth"},
{5, gfx::AttributeDataType::Float2, 1, "a_offset"},
{6, gfx::AttributeDataType::Float2, 1, "a_width"},
{7, gfx::AttributeDataType::UShort4, 1, "a_pattern_from"},
{8, gfx::AttributeDataType::UShort4, 1, "a_pattern_to"},
};
static constexpr UniformBlockInfo uniforms[] = {
MLN_MTL_UNIFORM_BLOCK(9, true, true, LinePatternUBO),
MLN_MTL_UNIFORM_BLOCK(10, true, false, LinePatternPropertiesUBO),
MLN_MTL_UNIFORM_BLOCK(11, true, false, LinePatternInterpolationUBO),
MLN_MTL_UNIFORM_BLOCK(12, true, false, LinePatternTilePropertiesUBO),
MLN_MTL_UNIFORM_BLOCK(13, true, true, LinePermutationUBO),
MLN_MTL_UNIFORM_BLOCK(14, true, false, ExpressionInputsUBO),
};
static constexpr TextureInfo textures[] = {
{0, "u_image"},
};
static constexpr auto source = R"(
struct VertexStage {
short2 pos_normal [[attribute(0)]];
uchar4 data [[attribute(1)]];
float2 blur [[attribute(2)]];
float2 opacity [[attribute(3)]];
float2 gapwidth [[attribute(4)]];
float2 offset [[attribute(5)]];
float2 width [[attribute(6)]];
ushort4 pattern_from [[attribute(7)]];
ushort4 pattern_to [[attribute(8)]];
};
struct FragmentStage {
float4 position [[position, invariant]];
float2 width2;
float2 normal;
float gamma_scale;
float blur;
float opacity;
float4 pattern_from;
float4 pattern_to;
float linesofar;
};
struct alignas(16) LinePatternUBO {
float4x4 matrix;
float4 scale;
float2 texsize;
float2 units_to_pixels;
float ratio;
float device_pixel_ratio;
float fade;
float pad1;
};
struct alignas(16) LinePatternPropertiesUBO {
float blur;
float opacity;
float offset;
float gapwidth;
float width;
float pad1, pad2, pad3;
};
struct alignas(16) LinePatternInterpolationUBO {
float blur_t;
float opacity_t;
float offset_t;
float gapwidth_t;
float width_t;
float pattern_from_t;
float pattern_to_t;
float pad1;
};
struct alignas(16) LinePatternTilePropertiesUBO {
float4 pattern_from;
float4 pattern_to;
};
FragmentStage vertex vertexMain(thread const VertexStage vertx [[stage_in]],
device const LinePatternUBO& line [[buffer(9)]],
device const LinePatternPropertiesUBO& props [[buffer(10)]],
device const LinePatternInterpolationUBO& interp [[buffer(11)]],
device const LinePatternTilePropertiesUBO& tileProps [[buffer(12)]],
device const LinePermutationUBO& permutation [[buffer(13)]],
device const ExpressionInputsUBO& expr [[buffer(14)]]) {
const auto blur = valueFor(permutation.blur, props.blur, vertx.blur, interp.blur_t, expr);
const auto opacity = valueFor(permutation.opacity, props.opacity, vertx.opacity, interp.opacity_t, expr);
const auto gapwidth = valueFor(permutation.gapwidth, props.gapwidth, vertx.gapwidth, interp.gapwidth_t, expr) / 2;
const auto offset = valueFor(permutation.offset, props.offset, vertx.offset, interp.offset_t, expr) * -1;
const auto width = valueFor(permutation.width, props.width, vertx.width, interp.width_t, expr);
const auto pattern_from = patternFor(permutation.pattern_from, tileProps.pattern_from, vertx.pattern_from, interp.pattern_from_t, expr);
const auto pattern_to = patternFor(permutation.pattern_to, tileProps.pattern_to, vertx.pattern_to, interp.pattern_to_t, expr);
// the distance over which the line edge fades out.
// Retina devices need a smaller distance to avoid aliasing.
const float ANTIALIASING = 1.0 / line.device_pixel_ratio / 2.0;
const float LINE_DISTANCE_SCALE = 2.0;
const float2 a_extrude = float2(vertx.data.xy) - 128.0;
const float a_direction = fmod(float(vertx.data.z), 4.0) - 1.0;
float linesofar = (floor(vertx.data.z / 4.0) + vertx.data.w * 64.0) * LINE_DISTANCE_SCALE;
const float2 pos = floor(float2(vertx.pos_normal) * 0.5);
// x is 1 if it's a round cap, 0 otherwise
// y is 1 if the normal points up, and -1 if it points down
// We store these in the least significant bit of a_pos_normal
const float2 normal = float2(vertx.pos_normal) - 2.0 * pos;
const float2 v_normal = float2(normal.x, normal.y * 2.0 - 1.0);
const float halfwidth = width / 2.0;
const float inset = gapwidth + (gapwidth > 0.0 ? ANTIALIASING : 0.0);
const float outset = gapwidth + halfwidth * (gapwidth > 0.0 ? 2.0 : 1.0) + (halfwidth == 0.0 ? 0.0 : ANTIALIASING);
// Scale the extrusion vector down to a normal and then up by the line width of this vertex.
const float2 dist = outset * a_extrude * LINE_NORMAL_SCALE;
// Calculate the offset when drawing a line that is to the side of the actual line.
// We do this by creating a vector that points towards the extrude, but rotate
// it when we're drawing round end points (a_direction = -1 or 1) since their
// extrude vector points in another direction.
const float u = 0.5 * a_direction;
const float t = 1.0 - abs(u);
const float2 offset2 = offset * a_extrude * LINE_NORMAL_SCALE * v_normal.y * float2x2(t, -u, u, t);
const float4 projected_extrude = line.matrix * float4(dist / line.ratio, 0.0, 0.0);
const float4 position = line.matrix * float4(pos + offset2 / line.ratio, 0.0, 1.0) + projected_extrude;
// calculate how much the perspective view squishes or stretches the extrude
const float extrude_length_without_perspective = length(dist);
const float extrude_length_with_perspective = length(projected_extrude.xy / position.w * line.units_to_pixels);
return {
.position = position,
.width2 = float2(outset, inset),
.normal = v_normal,
.gamma_scale = extrude_length_without_perspective / extrude_length_with_perspective,
.blur = blur,
.opacity = opacity,
.pattern_from = pattern_from,
.pattern_to = pattern_to,
.linesofar = linesofar,
};
}
half4 fragment fragmentMain(FragmentStage in [[stage_in]],
device const LinePatternUBO& line [[buffer(9)]],
device const LinePermutationUBO& permutation [[buffer(13)]],
texture2d<float, access::sample> image0 [[texture(0)]],
sampler image0_sampler [[sampler(0)]]) {
if (permutation.overdrawInspector) {
return half4(1.0);
}
float2 pattern_tl_a = in.pattern_from.xy;
float2 pattern_br_a = in.pattern_from.zw;
float2 pattern_tl_b = in.pattern_to.xy;
float2 pattern_br_b = in.pattern_to.zw;
float pixelRatio = line.scale.x;
float tileZoomRatio = line.scale.y;
float fromScale = line.scale.z;
float toScale = line.scale.w;
float2 display_size_a = float2((pattern_br_a.x - pattern_tl_a.x) / pixelRatio, (pattern_br_a.y - pattern_tl_a.y) / pixelRatio);
float2 display_size_b = float2((pattern_br_b.x - pattern_tl_b.x) / pixelRatio, (pattern_br_b.y - pattern_tl_b.y) / pixelRatio);
float2 pattern_size_a = float2(display_size_a.x * fromScale / tileZoomRatio, display_size_a.y);
float2 pattern_size_b = float2(display_size_b.x * toScale / tileZoomRatio, display_size_b.y);
// Calculate the distance of the pixel from the line in pixels.
float dist = length(in.normal) * in.width2.x;
// Calculate the antialiasing fade factor. This is either when fading in
// the line in case of an offset line (in.width2.y) or when fading out
// (in.width2.x)
float blur2 = (in.blur + 1.0 / DEVICE_PIXEL_RATIO) * in.gamma_scale;
float alpha = clamp(min(dist - (in.width2.y - blur2), in.width2.x - dist) / blur2, 0.0, 1.0);
float x_a = glMod(in.linesofar / pattern_size_a.x, 1.0);
float x_b = glMod(in.linesofar / pattern_size_b.x, 1.0);
// in.normal.y is 0 at the midpoint of the line, -1 at the lower edge, 1 at the upper edge
// we clamp the line width outset to be between 0 and half the pattern height plus padding (2.0)
// to ensure we don't sample outside the designated symbol on the sprite sheet.
// 0.5 is added to shift the component to be bounded between 0 and 1 for interpolation of
// the texture coordinate
float y_a = 0.5 + (in.normal.y * clamp(in.width2.x, 0.0, (pattern_size_a.y + 2.0) / 2.0) / pattern_size_a.y);
float y_b = 0.5 + (in.normal.y * clamp(in.width2.x, 0.0, (pattern_size_b.y + 2.0) / 2.0) / pattern_size_b.y);
float2 pos_a = mix(pattern_tl_a / line.texsize, pattern_br_a / line.texsize, float2(x_a, y_a));
float2 pos_b = mix(pattern_tl_b / line.texsize, pattern_br_b / line.texsize, float2(x_b, y_b));
float4 color = mix(image0.sample(image0_sampler, pos_a), image0.sample(image0_sampler, pos_b), line.fade);
return half4(color * alpha * in.opacity);
}
)";
};
} // namespace shaders
} // namespace mbgl

1
src/mbgl/mtl/buffer_resource.cpp
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@@ -1,6 +1,7 @@
#include <mbgl/mtl/buffer_resource.hpp>
#include <Metal/MTLDevice.hpp>
#include <algorithm>
namespace mbgl {
namespace mtl {

2
src/mbgl/mtl/renderer_backend.cpp
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@@ -137,7 +137,7 @@ void RendererBackend::initShaders(gfx::ShaderRegistry& shaders, const ProgramPar
shaders::BuiltIn::LineShader,
shaders::BuiltIn::LineGradientShader,
// shaders::BuiltIn::LineSDFShader,
// shaders::BuiltIn::LinePatternShader,
shaders::BuiltIn::LinePatternShader,
shaders::BuiltIn::RasterShader,
shaders::BuiltIn::SymbolIconShader,
shaders::BuiltIn::SymbolSDFIconShader,