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// Copyright 2021, 2022 Benjamin Barenblat
//
// 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
//
// https://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.
#include "src/glplanet.h"
#include <math.h>
#include <stdlib.h>
#include <chrono>
#include <iostream>
#include <stdexcept>
#include <type_traits>
#include <utility>
#include <vector>
#include "res/res.h"
#include "src/egl.h"
#include "src/gl/draw.h"
#include "src/gl/init.h"
#include "src/scene.h"
#include "src/x/connection.h"
#include "src/x/event.h"
#include "src/x/rpc.h"
#include "src/x/screen.h"
#include "src/x/types.h"
#include "third_party/abseil/absl/meta/type_traits.h"
#include "third_party/abseil/absl/strings/string_view.h"
#include "third_party/abseil/absl/types/span.h"
#include "third_party/abseil/absl/types/variant.h"
namespace glplanet {
namespace {
constexpr double kRadiansPerDegree = M_PI / 180.0;
x::Connection ConnectToDisplaySpecifiedInEnvironment() {
const char* display_name = getenv("DISPLAY");
if (display_name == nullptr) {
throw std::runtime_error("DISPLAY unset");
}
return x::Connection(display_name);
}
} // namespace
int Main(const MainOptions& options) {
x::Connection x = ConnectToDisplaySpecifiedInEnvironment();
egl::Display egl(x.AsXlibDisplay());
// Find an X visual that corresponds to our desired OpenGL settings.
egl::Configuration config =
egl.GetConfigurations(
{
{egl::kRedSize, 8},
{egl::kGreenSize, 8},
{egl::kBlueSize, 8},
{egl::kDepthSize, 1},
{egl::kRenderableTypeMask, egl::kOpenglBit},
{egl::kSampleBuffers, 1},
{egl::kSamples, 4},
},
/*limit=*/1)
.at(0);
x::Id visual = config.Get(egl::kNativeVisualId);
// Create the window we're going to display in, and tell X to map it. Set the
// window background to black so that if any newly exposed regions are briefly
// visible before being drawn on, the X server will fill them with the
// blackness of space.
std::vector<x::VoidCompletion> completions;
x::Screen screen = x.DefaultScreen();
x::Id window = x.GenerateId();
completions.push_back(x.CreateWindow({
.depth = screen.DepthOfVisual(visual),
.window = window,
.parent = screen.root(),
.x = 0,
.y = 0,
.width = 640,
.height = 480,
.border_width = 0,
.window_class = x::WindowClass::kInputOutput,
.visual_id = visual,
.background_pixel = screen.black_pixel(),
.event_mask = x::kExposure | x::kStructureNotify,
}));
completions.push_back(x.MapWindow(window));
// Create a rendering surface on the window and an OpenGL context to draw into
// that surface, and make that context current.
egl::Surface surface = egl.CreateWindowSurface(config, window);
egl::Context context = egl.CreateContext(config, egl::Api::kOpengl,
/*major=*/3,
/*minor=*/2);
egl::BindContext(surface, context);
gl::InitializeForThisThread();
gl::Enable(gl::Capability::kDepthTest);
gl::Enable(gl::Capability::kFramebufferSrgb);
// TODO(bbarenblat@gmail.com): Khronos says multisampling is turned on by
// default (see glEnable(3)). Do we actually need to turn it on explicitly?
gl::Enable(gl::Capability::kMultisample);
gl::SetClearColor(0.0, 0.0, 0.0, 1.0);
Scene scene({
.longitude_radians = options.longitude_degrees * kRadiansPerDegree,
.latitude_radians = options.latitude_degrees * kRadiansPerDegree,
});
scene.SetGlState();
// Ensure the window is mapped before we start drawing.
for (auto& completion : completions) {
std::move(completion).Check();
}
x::EventMonitor events(x);
int width = 640, height = 480;
while (true) {
// Handle any pending events.
int new_width = width, new_height = height;
while (absl::optional<x::Event> event = events.GetEventIfReady()) {
absl::visit(
[&](auto&& ev) {
using T = absl::decay_t<decltype(ev)>;
if constexpr (std::is_same_v<T, x::ConfigureNotifyEvent>) {
new_width = ev.width();
new_height = ev.height();
}
},
*event);
}
if (new_width != width || new_height != height) {
// Reset the viewport so the globe is centered and unsquashed.
int min_dimension = std::min(new_width, new_height);
int x_offset = (new_width - min_dimension) / 2;
int y_offset = (new_height - min_dimension) / 2;
gl::Clear({gl::GlBuffer::kColor});
gl::SetViewport(x_offset, y_offset, min_dimension, min_dimension);
width = new_width;
height = new_height;
}
gl::Clear({gl::GlBuffer::kDepth});
scene.Draw(std::chrono::system_clock::now());
// Wait for the frame to be displayed.
surface.SwapBuffers();
// TODO(bbarenblat@gmail.com): Actually get a target frame rate going based
// on the display size, rather than clamping to ~6 fps.
usleep(96'000);
}
return 0;
}
} // namespace glplanet
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