cca3adb375
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
128 lines
3.7 KiB
C++
128 lines
3.7 KiB
C++
// Generated code, do not modify this file!
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#pragma once
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#include <mbgl/shaders/shader_source.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::HeatmapShader, gfx::Backend::Type::OpenGL> {
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static constexpr const char* name = "HeatmapShader";
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static constexpr const char* vertex = R"(layout (location = 0) in vec2 a_pos;
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out vec2 v_extrude;
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layout (std140) uniform HeatmapDrawableUBO {
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highp mat4 u_matrix;
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highp float u_extrude_scale;
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lowp float drawable_pad1;
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lowp vec2 drawable_pad2;
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};
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layout (std140) uniform HeatmapEvaluatedPropsUBO {
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highp float u_weight;
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highp float u_radius;
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highp float u_intensity;
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lowp float props_pad1;
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};
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layout (std140) uniform HeatmapInterpolateUBO {
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lowp float u_weight_t;
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lowp float u_radius_t;
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lowp vec2 interp_pad1;
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};
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#ifndef HAS_UNIFORM_u_weight
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layout (location = 1) in highp vec2 a_weight;
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out highp float weight;
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#endif
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#ifndef HAS_UNIFORM_u_radius
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layout (location = 2) in mediump vec2 a_radius;
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#endif
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// Effective "0" in the kernel density texture to adjust the kernel size to;
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// this empirically chosen number minimizes artifacts on overlapping kernels
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// for typical heatmap cases (assuming clustered source)
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const highp float ZERO = 1.0 / 255.0 / 16.0;
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// Gaussian kernel coefficient: 1 / sqrt(2 * PI)
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#define GAUSS_COEF 0.3989422804014327
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void main(void) {
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#ifndef HAS_UNIFORM_u_weight
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weight = unpack_mix_vec2(a_weight, u_weight_t);
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#else
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highp float weight = u_weight;
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#endif
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#ifndef HAS_UNIFORM_u_radius
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mediump float radius = unpack_mix_vec2(a_radius, u_radius_t);
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#else
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mediump float radius = u_radius;
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#endif
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// unencode the extrusion vector that we snuck into the a_pos vector
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vec2 unscaled_extrude = vec2(mod(a_pos, 2.0) * 2.0 - 1.0);
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// This 'extrude' comes in ranging from [-1, -1], to [1, 1]. We'll use
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// it to produce the vertices of a square mesh framing the point feature
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// we're adding to the kernel density texture. We'll also pass it as
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// a varying, so that the fragment shader can determine the distance of
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// each fragment from the point feature.
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// Before we do so, we need to scale it up sufficiently so that the
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// kernel falls effectively to zero at the edge of the mesh.
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// That is, we want to know S such that
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// weight * u_intensity * GAUSS_COEF * exp(-0.5 * 3.0^2 * S^2) == ZERO
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// Which solves to:
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// S = sqrt(-2.0 * log(ZERO / (weight * u_intensity * GAUSS_COEF))) / 3.0
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float S = sqrt(-2.0 * log(ZERO / weight / u_intensity / GAUSS_COEF)) / 3.0;
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// Pass the varying in units of radius
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v_extrude = S * unscaled_extrude;
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// Scale by radius and the zoom-based scale factor to produce actual
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// mesh position
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vec2 extrude = v_extrude * radius * u_extrude_scale;
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// multiply a_pos by 0.5, since we had it * 2 in order to sneak
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// in extrusion data
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vec4 pos = vec4(floor(a_pos * 0.5) + extrude, 0, 1);
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gl_Position = u_matrix * pos;
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}
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)";
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static constexpr const char* fragment = R"(in vec2 v_extrude;
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layout (std140) uniform HeatmapEvaluatedPropsUBO {
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highp float u_weight;
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highp float u_radius;
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highp float u_intensity;
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lowp float props_pad1;
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};
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#ifndef HAS_UNIFORM_u_weight
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in highp float weight;
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#endif
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// Gaussian kernel coefficient: 1 / sqrt(2 * PI)
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#define GAUSS_COEF 0.3989422804014327
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void main() {
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#ifdef HAS_UNIFORM_u_weight
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highp float weight = u_weight;
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#endif
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// Kernel density estimation with a Gaussian kernel of size 5x5
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float d = -0.5 * 3.0 * 3.0 * dot(v_extrude, v_extrude);
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float val = weight * u_intensity * GAUSS_COEF * exp(d);
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fragColor = vec4(val, 1.0, 1.0, 1.0);
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#ifdef OVERDRAW_INSPECTOR
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fragColor = vec4(1.0);
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#endif
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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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