a9ddf5b7fd
Port of https://github.com/mapbox/mapbox-gl-js/pull/5101: adds a new render pass `Pass3D` before any other rendering wherein we render layers with 3D passes (fill-extrusion layers) to offscreen framebuffers, sharing a depth renderbuffer between those layers in order to render 3D space correctly. Those framebuffers are saved on the RenderLayers and copied back to the map during the translucent pass. Rendering to offscreen framebuffers before we do any clear + draw means we can avoid expensive framebuffer restores.
93 lines
3.3 KiB
C++
93 lines
3.3 KiB
C++
#pragma once
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#include <mbgl/renderer/backend_scope.hpp>
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#include <mbgl/util/image.hpp>
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#include <mbgl/util/size.hpp>
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#include <mbgl/util/util.hpp>
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#include <memory>
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#include <mutex>
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namespace mbgl {
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namespace gl {
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class Context;
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using ProcAddress = void (*)();
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using FramebufferID = uint32_t;
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} // namespace gl
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// The RendererBackend is used by the Renderer to facilitate
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// the actual rendering.
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class RendererBackend {
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public:
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RendererBackend();
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virtual ~RendererBackend();
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// Returns the backend's context which manages OpenGL state.
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gl::Context& getContext();
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// Called prior to rendering to update the internally assumed OpenGL state.
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virtual void updateAssumedState() = 0;
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// Called when this backend is used for rendering. Implementations should ensure that a renderable
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// object is bound and glClear/glDraw* calls can be done. They should also make sure that
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// calling .bind() repeatedly is a no-op and that the appropriate gl::Context values are
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// set to the current state.
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virtual void bind() = 0;
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virtual Size getFramebufferSize() const = 0;
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protected:
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// Called with the name of an OpenGL extension that should be loaded. RendererBackend implementations
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// must call the API-specific version that obtains the function pointer for this function,
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// or a null pointer if unsupported/unavailable.
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virtual gl::ProcAddress initializeExtension(const char*) = 0;
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// Called when the backend's GL context needs to be made active or inactive. These are called,
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// as a matched pair, exclusively through BackendScope, in two situations:
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//
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// 1. When releasing GL resources during Renderer destruction
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// (Including calling CustomLayerDeinitializeFunction during RenderCustomLayer destruction)
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// 2. When renderering through Renderer::render()
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// (Including calling CustomLayerDeinitializeFunction for newly added custom layers and
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// CustomLayerDeinitializeFunction on layer removal)
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virtual void activate() = 0;
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virtual void deactivate() = 0;
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// Reads the color pixel data from the currently bound framebuffer.
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PremultipliedImage readFramebuffer(const Size&) const;
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// A constant to signal that a framebuffer is bound, but with an unknown ID.
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static constexpr const gl::FramebufferID ImplicitFramebufferBinding =
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std::numeric_limits<gl::FramebufferID>::max();
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// Tells the renderer that OpenGL state has already been set by the windowing toolkit.
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// It sets the internal assumed state to the supplied values.
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void assumeFramebufferBinding(gl::FramebufferID fbo);
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void assumeViewport(int32_t x, int32_t y, const Size&);
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void assumeScissorTest(bool);
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// Returns true when assumed framebuffer binding hasn't changed from the implicit binding.
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bool implicitFramebufferBound();
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// Triggers an OpenGL state update if the internal assumed state doesn't match the
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// supplied values.
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void setFramebufferBinding(gl::FramebufferID fbo);
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void setViewport(int32_t x, int32_t y, const Size&);
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void setScissorTest(bool);
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protected:
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std::unique_ptr<gl::Context> context;
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private:
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std::once_flag initialized;
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friend class BackendScope;
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};
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MBGL_CONSTEXPR bool operator==(const RendererBackend& a, const RendererBackend& b) {
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return &a == &b;
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}
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} // namespace mbgl
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