1 files changed, 105 insertions, 0 deletions
diff --git a/src/mbgl/gl/render_custom_layer.cpp b/src/mbgl/gl/render_custom_layer.cpp
new file mode 100644
index 0000000000..85c060c740
--- /dev/null
+++ b/src/mbgl/gl/render_custom_layer.cpp
@@ -0,0 +1,105 @@
+#include <mbgl/gfx/backend_scope.hpp>
+#include <mbgl/gfx/renderer_backend.hpp>
+#include <mbgl/map/transform_state.hpp>
+#include <mbgl/platform/gl_functions.hpp>
+#include <mbgl/renderer/bucket.hpp>
+#include <mbgl/renderer/paint_parameters.hpp>
+#include <mbgl/style/layers/custom_layer_impl.hpp>
+#include <mbgl/gl/context.hpp>
+#include <mbgl/gl/render_custom_layer.hpp>
+#include <mbgl/gl/renderable_resource.hpp>
+#include <mbgl/util/mat4.hpp>
+
+namespace mbgl {
+
+using namespace style;
+
+namespace {
+
+inline const CustomLayer::Impl& impl(const Immutable<style::Layer::Impl>& impl) {
+    assert(impl->getTypeInfo() == CustomLayer::Impl::staticTypeInfo());
+    return static_cast<const CustomLayer::Impl&>(*impl);
+}
+
+} // namespace
+
+RenderCustomLayer::RenderCustomLayer(Immutable<style::CustomLayer::Impl> _impl)
+    : RenderLayer(makeMutable<CustomLayerProperties>(std::move(_impl))),
+      host(impl(baseImpl).host) {
+    assert(gfx::BackendScope::exists());
+    MBGL_CHECK_ERROR(host->initialize());
+}
+
+RenderCustomLayer::~RenderCustomLayer() {
+    assert(gfx::BackendScope::exists());
+    if (contextDestroyed) {
+        host->contextLost();
+    } else {
+        MBGL_CHECK_ERROR(host->deinitialize());
+    }
+}
+
+void RenderCustomLayer::evaluate(const PropertyEvaluationParameters&) {
+    passes = RenderPass::Translucent;
+    // It is fine to not update `evaluatedProperties`, as `baseImpl` should never be updated for this layer.
+}
+
+bool RenderCustomLayer::hasTransition() const {
+    return false;
+}
+bool RenderCustomLayer::hasCrossfade() const {
+    return false;
+}
+
+void RenderCustomLayer::markContextDestroyed() {
+    contextDestroyed = true;
+}
+
+void RenderCustomLayer::prepare(const LayerPrepareParameters&) {
+}
+
+void RenderCustomLayer::render(PaintParameters& paintParameters) {
+    if (host != impl(baseImpl).host) {
+        //If the context changed, deinitialize the previous one before initializing the new one.
+        if (host && !contextDestroyed) {
+            MBGL_CHECK_ERROR(host->deinitialize());
+        }
+        host = impl(baseImpl).host;
+        MBGL_CHECK_ERROR(host->initialize());
+    }
+
+    const TransformState& state = paintParameters.state;
+
+    // TODO: remove cast
+    auto& glContext = static_cast<gl::Context&>(paintParameters.context);
+    // Reset GL state to a known state so the CustomLayer always has a clean slate.
+    glContext.bindVertexArray = 0;
+    glContext.setDepthMode(paintParameters.depthModeForSublayer(0, gfx::DepthMaskType::ReadOnly));
+    glContext.setStencilMode(gfx::StencilMode::disabled());
+    glContext.setColorMode(paintParameters.colorModeForRenderPass());
+    glContext.setCullFaceMode(gfx::CullFaceMode::disabled());
+
+    CustomLayerRenderParameters parameters;
+
+    parameters.width = state.getSize().width;
+    parameters.height = state.getSize().height;
+    parameters.latitude = state.getLatLng().latitude();
+    parameters.longitude = state.getLatLng().longitude();
+    parameters.zoom = state.getZoom();
+    parameters.bearing = -state.getBearing() * util::RAD2DEG;
+    parameters.pitch = state.getPitch();
+    parameters.fieldOfView = state.getFieldOfView();
+    mat4 projMatrix;
+    state.getProjMatrix(projMatrix);
+    parameters.projectionMatrix = projMatrix;
+
+    MBGL_CHECK_ERROR(host->render(parameters));
+    if (gfx::Backend::GetType() == gfx::Backend::Type::OpenGL) {
+        // Reset the view back to our original one, just in case the CustomLayer changed
+        // the viewport or Framebuffer.
+        paintParameters.backend.getDefaultRenderable().getResource<gl::RenderableResource>().bind();
+        glContext.setDirtyState();
+    }
+}
+
+} // namespace mbgl