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