[core, ios, macos, android, node] Heatmap layer (#11046)

Co-Authored-By: Konstantin Käfer <mail@kkaefer.com>
Co-Authored-By: Anand Thakker <anandthakker@users.noreply.github.com>
Co-Authored-By: Minh Nguyễn <1ec5@users.noreply.github.com>

src/mbgl/renderer/layers/render_heatmap_layer.cpp

@@ -0,0 +1,178 @@
+#include <mbgl/renderer/layers/render_heatmap_layer.hpp>
+#include <mbgl/renderer/buckets/heatmap_bucket.hpp>
+#include <mbgl/renderer/render_tile.hpp>
+#include <mbgl/renderer/paint_parameters.hpp>
+#include <mbgl/renderer/render_static_data.hpp>
+#include <mbgl/programs/programs.hpp>
+#include <mbgl/programs/heatmap_program.hpp>
+#include <mbgl/tile/tile.hpp>
+#include <mbgl/style/layers/heatmap_layer.hpp>
+#include <mbgl/style/layers/heatmap_layer_impl.hpp>
+#include <mbgl/geometry/feature_index.hpp>
+#include <mbgl/util/math.hpp>
+#include <mbgl/util/intersection_tests.hpp>
+
+namespace mbgl {
+
+using namespace style;
+
+RenderHeatmapLayer::RenderHeatmapLayer(Immutable<style::HeatmapLayer::Impl> _impl)
+    : RenderLayer(style::LayerType::Heatmap, _impl),
+    unevaluated(impl().paint.untransitioned()), colorRamp({256, 1}) {
+}
+
+const style::HeatmapLayer::Impl& RenderHeatmapLayer::impl() const {
+    return static_cast<const style::HeatmapLayer::Impl&>(*baseImpl);
+}
+
+std::unique_ptr<Bucket> RenderHeatmapLayer::createBucket(const BucketParameters& parameters, const std::vector<const RenderLayer*>& layers) const {
+    return std::make_unique<HeatmapBucket>(parameters, layers);
+}
+
+void RenderHeatmapLayer::transition(const TransitionParameters& parameters) {
+    unevaluated = impl().paint.transitioned(parameters, std::move(unevaluated));
+}
+
+void RenderHeatmapLayer::evaluate(const PropertyEvaluationParameters& parameters) {
+    evaluated = unevaluated.evaluate(parameters);
+
+    passes = (evaluated.get<style::HeatmapOpacity>() > 0)
+            ? (RenderPass::Translucent | RenderPass::Pass3D)
+            : RenderPass::None;
+}
+
+bool RenderHeatmapLayer::hasTransition() const {
+    return unevaluated.hasTransition();
+}
+
+void RenderHeatmapLayer::render(PaintParameters& parameters, RenderSource*) {
+    if (parameters.pass == RenderPass::Opaque) {
+        return;
+    }
+
+    if (parameters.pass == RenderPass::Pass3D) {
+        const auto& viewportSize = parameters.staticData.backendSize;
+        const auto size = Size{viewportSize.width / 4, viewportSize.height / 4};
+
+        if (!renderTexture || renderTexture->getSize() != size) {
+            if (parameters.context.supportsHalfFloatTextures) {
+                renderTexture = OffscreenTexture(parameters.context, size, gl::TextureType::HalfFloat);
+
+                try {
+                    renderTexture->bind();
+                } catch (const std::runtime_error& ex) {
+                    // can't render to a half-float texture; falling back to unsigned byte one
+                    renderTexture = nullopt;
+                    parameters.context.supportsHalfFloatTextures = false;
+                }
+            }
+
+            if (!renderTexture) {
+                renderTexture = OffscreenTexture(parameters.context, size, gl::TextureType::UnsignedByte);
+                renderTexture->bind();
+            }
+
+        } else {
+            renderTexture->bind();
+        }
+
+        if (!colorRampTexture) {
+            colorRampTexture = parameters.context.createTexture(colorRamp, 1, gl::TextureType::UnsignedByte);
+        }
+
+        parameters.context.clear(Color{ 0.0f, 0.0f, 0.0f, 1.0f }, {}, {});
+
+        for (const RenderTile& tile : renderTiles) {
+            assert(dynamic_cast<HeatmapBucket*>(tile.tile.getBucket(*baseImpl)));
+            HeatmapBucket& bucket = *reinterpret_cast<HeatmapBucket*>(tile.tile.getBucket(*baseImpl));
+
+            const auto extrudeScale = tile.id.pixelsToTileUnits(1, parameters.state.getZoom());
+
+            const auto stencilMode = parameters.mapMode != MapMode::Continuous
+                ? parameters.stencilModeForClipping(tile.clip)
+                : gl::StencilMode::disabled();
+
+            parameters.programs.heatmap.get(evaluated).draw(
+                parameters.context,
+                gl::Triangles(),
+                parameters.depthModeForSublayer(0, gl::DepthMode::ReadOnly),
+                stencilMode,
+                gl::ColorMode::additive(),
+                HeatmapProgram::UniformValues {
+                    uniforms::u_intensity::Value{evaluated.get<style::HeatmapIntensity>()},
+                    uniforms::u_matrix::Value{tile.matrix},
+                    uniforms::heatmap::u_extrude_scale::Value{extrudeScale}
+                },
+                *bucket.vertexBuffer,
+                *bucket.indexBuffer,
+                bucket.segments,
+                bucket.paintPropertyBinders.at(getID()),
+                evaluated,
+                parameters.state.getZoom(),
+                getID()
+            );
+        }
+
+    } else if (parameters.pass == RenderPass::Translucent) {
+        parameters.context.bindTexture(renderTexture->getTexture(), 0, gl::TextureFilter::Linear);
+        parameters.context.bindTexture(*colorRampTexture, 1, gl::TextureFilter::Linear);
+
+        const auto& size = parameters.staticData.backendSize;
+
+        mat4 viewportMat;
+        matrix::ortho(viewportMat, 0, size.width, size.height, 0, 0, 1);
+
+        const Properties<>::PossiblyEvaluated properties;
+
+        parameters.programs.heatmapTexture.draw(
+            parameters.context, gl::Triangles(), gl::DepthMode::disabled(),
+            gl::StencilMode::disabled(), parameters.colorModeForRenderPass(),
+            HeatmapTextureProgram::UniformValues{
+                uniforms::u_matrix::Value{ viewportMat }, uniforms::u_world::Value{ size },
+                uniforms::u_image::Value{ 0 },
+                uniforms::u_color_ramp::Value{ 1 },
+                uniforms::u_opacity::Value{ evaluated.get<HeatmapOpacity>() } },
+            parameters.staticData.extrusionTextureVertexBuffer,
+            parameters.staticData.quadTriangleIndexBuffer,
+            parameters.staticData.extrusionTextureSegments,
+            HeatmapTextureProgram::PaintPropertyBinders{ properties, 0 }, properties,
+            parameters.state.getZoom(), getID());
+    }
+}
+
+void RenderHeatmapLayer::updateColorRamp() {
+    auto colorValue = unevaluated.get<HeatmapColor>().getValue();
+    if (colorValue.isUndefined()) {
+        colorValue = HeatmapLayer::getDefaultHeatmapColor();
+    }
+
+    const auto length = colorRamp.bytes();
+
+    for (uint32_t i = 0; i < length; i += 4) {
+        const auto color = colorValue.evaluate(static_cast<double>(i) / length);
+        colorRamp.data[i + 0] = std::floor(color.r * 255);
+        colorRamp.data[i + 1] = std::floor(color.g * 255);
+        colorRamp.data[i + 2] = std::floor(color.b * 255);
+        colorRamp.data[i + 3] = std::floor(color.a * 255);
+    }
+
+    if (colorRampTexture) {
+        colorRampTexture = nullopt;
+    }
+}
+
+bool RenderHeatmapLayer::queryIntersectsFeature(
+        const GeometryCoordinates& queryGeometry,
+        const GeometryTileFeature& feature,
+        const float zoom,
+        const float bearing,
+        const float pixelsToTileUnits) const {
+    (void) queryGeometry;
+    (void) feature;
+    (void) zoom;
+    (void) bearing;
+    (void) pixelsToTileUnits;
+    return false;
+}
+
+} // namespace mbgl