101 lines
4.1 KiB
C++
101 lines
4.1 KiB
C++
// Copyright 2019 The MediaPipe Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef MEDIAPIPE_GPU_GL_QUAD_RENDERER_H_
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#define MEDIAPIPE_GPU_GL_QUAD_RENDERER_H_
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#include <optional>
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#include "absl/status/status.h"
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#include "mediapipe/gpu/gl_base.h"
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#include "mediapipe/gpu/scale_mode.pb.h"
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namespace mediapipe {
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// Valid rotation values. Counterclockwise.
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enum class FrameRotation { kNone, k90, k180, k270 };
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enum class FrameScaleMode {
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// Stretch the frame to the exact provided output dimensions.
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kStretch = 0,
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// Scale the frame up to fit the drawing area, preserving aspect ratio; may
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// letterbox.
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kFit,
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// Scale the frame up to fill the drawing area, preserving aspect ratio; may
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// crop.
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kFillAndCrop,
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};
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// Converts scale_mode.proto enum value typically used in calculator options
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// to FrameScaleMode value.
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FrameScaleMode FrameScaleModeFromProto(ScaleMode_Mode proto_scale_mode,
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FrameScaleMode default_mode);
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// This is a utility class containing some common code to render a texture on
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// a quadrilateral with aspect ratio correction, (quarter-circle) rotation,
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// mirroring and flipping. It is used in various places where rendering is
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// done.
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class QuadRenderer {
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public:
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QuadRenderer() {}
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// Creates the rendering program. Must be called within the GL context that
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// will be used for rendering.
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absl::Status GlSetup();
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// Creates the rendering program. Must be called within the GL context that
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// will be used for rendering.
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// This version allows you to customize the fragment shader.
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absl::Status GlSetup(const GLchar* custom_frag_shader,
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const std::vector<const GLchar*>& custom_frame_uniforms);
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// Renders the texture bound to texture unit 1 onto the current viewport.
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// Note: mirroring and flipping are handled differently, by design.
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// - flip_texture is meant to be used when the texture image's rows are stored
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// top-to-bottom. The OpenGL custom is to store them bottom-to-top, but this
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// is the opposite of the way most other graphics APIs and formats represent
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// images, so having flipped textures is quite common.
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// Because this is a property of the input texture, flipping is applied
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// BEFORE rotation.
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// - flip_horizontal is meant to be used to flip the output image
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// horizontally. This is especially useful for the front-facing camera on
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// smartphones. This flipping is applied AFTER rotation, because that is
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// what's needed for the front-camera use case.
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// - flip_vertical is meant to be used to flip the output image vertically.
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// This flipping is applied AFTER rotation.
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absl::Status GlRender(float frame_width, float frame_height, float view_width,
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float view_height, FrameScaleMode scale_mode,
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FrameRotation rotation, bool flip_horizontal,
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bool flip_vertical, bool flip_texture) const;
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// Deletes the rendering program. Must be called withn the GL context where
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// it was created.
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void GlTeardown();
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private:
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void UpdateVertices(FrameRotation rotation) const;
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GLuint program_ = 0;
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GLint scale_unif_ = -1;
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std::vector<GLint> frame_unifs_;
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GLuint vao_ = 0; // vertex array object
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GLuint vbo_[2] = {0, 0}; // for vertex buffer storage
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mutable std::optional<FrameRotation> rotation_;
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};
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absl::Status FrameRotationFromInt(FrameRotation* rotation, int degrees_ccw);
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// Input degrees must be one of: [0, 90, 180, 270].
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FrameRotation FrameRotationFromDegrees(int degrees_ccw);
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} // namespace mediapipe
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#endif // MEDIAPIPE_GPU_GL_QUAD_RENDERER_H_
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