237 lines
7.7 KiB
C++
237 lines
7.7 KiB
C++
#pragma once
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namespace mbgl {
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namespace shaders {
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constexpr auto prelude = R"(
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#include <metal_stdlib>
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using namespace metal;
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// The maximum allowed miter limit is 2.0 at the moment. the extrude normal is stored
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// in a byte (-128..127). We scale regular normals up to length 63, but there are also
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// "special" normals that have a bigger length (of up to 126 in this case).
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#define LINE_NORMAL_SCALE (1.0 / (127 / 2))
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// The attribute conveying progress along a line is scaled to [0, 2^15).
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#define MAX_LINE_DISTANCE 32767.0
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#define SDF_PX 8.0
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// OpenGL `mod` is `x-y*floor(x/y)` where `floor` rounds down.
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// Metal `fmod` is `x-y*trunc(x/y)` where `trunc` rounds toward zero.
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// This function provides GL-compatible modulus for porting GLSL shaders.
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template <typename T1, typename T2>
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inline auto glMod(T1 x, T2 y) { return x - y * metal::floor(x/y); }
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inline float radians(float degrees) {
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return M_PI_F * degrees / 180.0;
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}
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// Unpack a pair of values that have been packed into a single float.
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// The packed values are assumed to be 8-bit unsigned integers, and are
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// packed like so: packedValue = floor(input[0]) * 256 + input[1],
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float2 unpack_float(const float packedValue) {
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const int packedIntValue = int(packedValue);
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const int v0 = packedIntValue / 256;
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return float2(v0, packedIntValue - v0 * 256);
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}
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float2 unpack_opacity(const float packedOpacity) {
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return float2(float(int(packedOpacity) / 2) / 127.0, glMod(packedOpacity, 2.0));
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}
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// To minimize the number of attributes needed, we encode a 4-component
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// color into a pair of floats (i.e. a vec2) as follows:
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// [ floor(color.r * 255) * 256 + color.g * 255, floor(color.b * 255) * 256 + color.g * 255 ]
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float4 decode_color(const float2 encoded) {
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return float4(unpack_float(encoded[0]) / 255, unpack_float(encoded[1]) / 255);
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}
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// Unpack a pair of paint values and interpolate between them.
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float unpack_mix_float(const float2 packedValue, const float t) {
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return mix(packedValue[0], packedValue[1], t);
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}
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// Unpack a pair of paint values and interpolate between them.
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float4 unpack_mix_color(const float4 packedColors, const float t) {
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return mix(decode_color(float2(packedColors[0], packedColors[1])),
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decode_color(float2(packedColors[2], packedColors[3])), t);
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}
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// Unpack pattern position
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inline float2 get_pattern_pos(const float2 pixel_coord_upper, const float2 pixel_coord_lower,
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const float2 pattern_size, const float tile_units_to_pixels, const float2 pos) {
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const float2 offset = glMod(glMod(glMod(pixel_coord_upper, pattern_size) * 256.0, pattern_size) * 256.0 + pixel_coord_lower, pattern_size);
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return (tile_units_to_pixels * pos + offset) / pattern_size;
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}
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template<class ForwardIt, class T>
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ForwardIt upper_bound(ForwardIt first, ForwardIt last, thread const T& value)
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{
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size_t count = last - first;
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while (count > 0)
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{
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ForwardIt it = first;
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const size_t step = count / 2;
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it += step;
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if (!(value < *it))
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{
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first = ++it;
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count -= step + 1;
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}
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else {
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count = step;
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}
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}
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return first;
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}
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float interpolationFactor(float base, float rangeMin, float rangeMax, float z) {
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const float zoomDiff = rangeMax - rangeMin;
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const float zoomProgress = z - rangeMin;
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if (zoomDiff == 0) {
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return 0;
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} else if (base == 1.0f) {
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return zoomProgress / zoomDiff;
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} else {
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return (pow(base, zoomProgress) - 1) / (pow(base, zoomDiff) - 1);
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}
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}
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enum class GPUInterpType : uint16_t {
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Step,
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Linear,
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Exponential,
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Bezier
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};
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enum class GPUOutputType : uint16_t {
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Float,
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Color,
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};
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enum class GPUOptions : uint16_t {
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None = 0,
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IntegerZoom = 1 << 0,
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Transitioning = 1 << 1,
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};
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bool operator&(GPUOptions a, GPUOptions b) { return (uint16_t)a & (uint16_t)b; }
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constant const int maxExprStops = 16;
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struct alignas(16) GPUExpression {
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GPUOutputType outputType;
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uint16_t stopCount;
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GPUOptions options;
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GPUInterpType interpolation;
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union InterpOptions {
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struct Exponential {
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float base;
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} exponential;
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struct Bezier {
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float x1;
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float y1;
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float x2;
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float y2;
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} bezier;
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} interpOptions;
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float inputs[maxExprStops];
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union Stops {
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float floats[maxExprStops];
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float2 colors[maxExprStops];
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} stops;
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float eval(float zoom) device const {
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const auto effectiveZoom = (options & GPUOptions::IntegerZoom) ? floor(zoom) : zoom;
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const auto index = find(effectiveZoom);
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if (index == 0) {
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return stops.floats[0];
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} else if (index == stopCount) {
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return stops.floats[stopCount - 1];
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}
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switch (interpolation) {
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case GPUInterpType::Step: return stops.floats[index - 1];
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default: assert(false);
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[[fallthrough]];
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case GPUInterpType::Linear: assert(interpOptions.exponential.base == 1.0f);
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[[fallthrough]];
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case GPUInterpType::Exponential: {
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const float rangeBeg = inputs[index - 1];
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const float rangeEnd = inputs[index];
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const auto t = interpolationFactor(interpOptions.exponential.base, rangeBeg, rangeEnd, effectiveZoom);
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return mix(stops.floats[index - 1], stops.floats[index], t);
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}
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case GPUInterpType::Bezier:
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assert(false);
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return stops.floats[0];
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}
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}
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float4 evalColor(float zoom) device const {
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const auto effectiveZoom = (options & GPUOptions::IntegerZoom) ? floor(zoom) : zoom;
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const auto index = find(effectiveZoom);
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if (index == 0) {
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return getColor(0);
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} else if (index == stopCount) {
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return getColor(stopCount - 1);
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}
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switch (interpolation) {
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case GPUInterpType::Step:
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return getColor(index - 1);
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default:
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assert(false);
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[[fallthrough]];
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case GPUInterpType::Linear:
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assert(interpOptions.exponential.base == 1.0f);
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[[fallthrough]];
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case GPUInterpType::Exponential: {
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const float rangeBeg = inputs[index - 1];
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const float rangeEnd = inputs[index];
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const auto t = interpolationFactor(interpOptions.exponential.base, rangeBeg, rangeEnd, effectiveZoom);
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return mix(getColor(index - 1), getColor(index), clamp(t, 0.0, 1.0));
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}
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case GPUInterpType::Bezier:
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assert(false);
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return getColor(0);
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}
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}
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/// Get the index of the entry to use from the zoom level
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size_t find(float zoom) device const {
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return upper_bound(&inputs[0], &inputs[stopCount], zoom) - &inputs[0];
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}
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float4 getColor(size_t index) device const { return decode_color(stops.colors[index]); }
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};
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static_assert(sizeof(GPUExpression) == 32 + (4 + 8) * maxExprStops, "wrong size");
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static_assert(sizeof(GPUExpression) % 16 == 0, "wrong alignment");
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struct alignas(16) GlobalPaintParamsUBO {
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/* 0 */ float2 pattern_atlas_texsize;
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/* 8 */ float2 units_to_pixels;
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/* 16 */ float2 world_size;
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/* 24 */ float camera_to_center_distance;
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/* 28 */ float symbol_fade_change;
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/* 32 */ float aspect_ratio;
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/* 36 */ float pixel_ratio;
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/* 40 */ float map_zoom;
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/* 44 */ float pad1;
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/* 48 */
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};
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static_assert(sizeof(GlobalPaintParamsUBO) == 3 * 16, "wrong size");
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enum {
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idGlobalPaintParamsUBO,
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idGlobalUBOIndex,
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globalUBOCount,
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};
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enum {
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idDrawableReservedVertexOnlyUBO = globalUBOCount,
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idDrawableReservedFragmentOnlyUBO,
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drawableReservedUBOCount
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};
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)";
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}
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} // namespace mbgl
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