init - display part of screen on a vr overlay

.gitignore

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+overlay

Makefile

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+
+
+build:
+	CPATH=. g++ -lX11 -lglfw -lGL openvr/libopenvr_api.so src/main.cpp -o overlay
+
+run: build
+	./overlay
+

src/main.cpp

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+#include <signal.h>
+#include <assert.h>
+
+#include <X11/extensions/Xcomposite.h>
+#include <X11/Xutil.h>
+#include <GLFW/glfw3.h>
+
+#include "openvr/openvr.h"
+
+static vr::ETrackingUniverseOrigin TRACKING_UNIVERSE = vr::ETrackingUniverseOrigin::TrackingUniverseStanding;
+
+#define WIDTH 1024
+#define HEIGHT 1024
+
+Display *xdisplay;
+Window root_window;
+
+vr::IVRSystem *ovr_sys;
+vr::IVROverlay *ovr_overlay;
+vr::VROverlayHandle_t handle;
+
+GLuint overlaytexture;
+GLFWwindow *gl_window;
+
+void cleanup(int _sig = 0);
+
+int main(int argc, char **argv)
+{
+	signal(SIGINT, cleanup);
+	{
+		xdisplay = XOpenDisplay(nullptr);
+		assert(xdisplay != nullptr);
+		printf("Created X11 display\n");
+		root_window = XRootWindow(xdisplay, 0);
+	}
+
+	{
+		assert(glfwInit() == true);
+		glfwWindowHint(GLFW_VISIBLE, false);
+		gl_window = glfwCreateWindow(WIDTH, HEIGHT, "Overlay", nullptr, nullptr);
+		assert(gl_window != nullptr);
+		glfwMakeContextCurrent(gl_window);
+		printf("Created GLFW context\n");
+	}
+
+	{
+		vr::EVRInitError init_err;
+		ovr_sys = vr::VR_Init(&init_err, vr::EVRApplicationType::VRApplication_Overlay);
+		assert(init_err == 0);
+		ovr_overlay = vr::VROverlay();
+		printf("Initialized openvr overlay\n");
+	}
+
+	{
+		auto overlay_err = ovr_overlay->CreateOverlay("deskpot", "Desktop view", &handle);
+		assert(overlay_err == 0);
+		ovr_overlay->ShowOverlay(handle);
+		ovr_overlay->SetOverlayTextureColorSpace(handle, vr::EColorSpace::ColorSpace_Gamma);
+		ovr_overlay->SetOverlayWidthInMeters(handle, 0.5f);
+		uint8_t col[4] = {20, 100, 100, 255};
+		ovr_overlay->SetOverlayRaw(handle, &col, 1, 1, 4);
+		printf("Created overlay instance\n");
+	}
+
+	{
+		vr::HmdMatrix34_t transform;
+		auto err = ovr_overlay->GetOverlayTransformAbsolute(handle, &TRACKING_UNIVERSE, &transform);
+		assert(err == 0);
+		transform.m[1][1] = -1;
+		err = ovr_overlay->SetOverlayTransformAbsolute(handle, TRACKING_UNIVERSE, &transform);
+		assert(err == 0);
+	}
+
+	{
+		glGenTextures(1, &overlaytexture);
+		glBindTexture(GL_TEXTURE_2D, overlaytexture);
+	}
+
+	vr::Texture_t vr_texture;
+	vr_texture.eColorSpace = vr::EColorSpace::ColorSpace_Auto;
+	vr_texture.eType = vr::ETextureType::TextureType_OpenGL;
+
+	while (1)
+	{
+		auto frame = XGetImage(xdisplay, root_window, 0, 0, WIDTH, HEIGHT, AllPlanes, ZPixmap);
+		glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, WIDTH, HEIGHT, 0, GL_BGRA, GL_UNSIGNED_BYTE, frame->data);
+		XDestroyImage(frame);
+
+		{
+			vr_texture.handle = (void *)(uintptr_t)overlaytexture;
+			auto set_err = ovr_overlay->SetOverlayTexture(handle, &vr_texture);
+			if (set_err)
+			{
+				printf("error setting texture: %d\n", set_err);
+				assert(set_err == 0);
+			}
+		}
+		glfwSwapBuffers(gl_window);
+
+		ovr_overlay->WaitFrameSync(20);
+	}
+	cleanup();
+	return 0;
+}
+
+void cleanup(int _sig)
+{
+	printf("\nShutting down\n");
+	vr::VR_Shutdown();
+	glfwDestroyWindow(gl_window);
+	glfwTerminate();
+	exit(0);
+}