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// Copyright 2018 Google LLC
// 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
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
#include "tools/render/geometry_util.h"
#include "tools/render/sdl_util.h"
namespace quic_trace {
namespace render {
extern const char* kProgramStateData;
// The global state of the program that every component and shader has access
// to. There are some requirements regarding to how the format of this struct
// should be altered:
// 1. It should be kept in sync with the GLSL definition in .cc file.
// 2. There are some alignment rules that you have to follow, which are
// somewhat elaborate (search "std140" for more details), but the
// relevant part is that it's 4 bytes for floats and 8 bytes for 2D vectors.
struct ProgramStateData {
// Size of the program window in pixels.
vec2 window = vec2{1280.f, 720.f};
// Starting point, in axis units (us/bytes), of the part of the trace that is
// currently shown.
vec2 offset = vec2{0.f, 0.f};
// Size of the portion of the trace that is currently shown, in pixels.
vec2 viewport = vec2{0.f, 0.f};
// The factor by which UI elements need to be scaled due to the DPI.
alignas(sizeof(float)) float dpi_scale = 1.f;
// A wrapper around ProgramStateData for the consumers of the data. Allows
// access to the members of ProgramStateData as well as the copy of them in GPU
// memory.
class ProgramState {
ProgramState(const ProgramStateData* data);
ProgramState(const ProgramState&) = delete;
ProgramState& operator=(const ProgramState&) = delete;
const vec2& window() const { return data_->window; }
const vec2& offset() const { return data_->offset; }
const vec2& viewport() const { return data_->viewport; }
float dpi_scale() const { return data_->dpi_scale; }
int ScaleForDpi(int value) const {
return std::round(data_->dpi_scale * value);
// Binds the Uniform Buffer Object with |data_| onto the specified shader
// program.
void Bind(const GlProgram& program) const;
// Copies |data_| into |buffer_|.
void Refresh();
// Data on host.
const ProgramStateData* data_;
// Handle to data on the device.
GlUniformBuffer buffer_;
} // namespace render
} // namespace quic_trace