From 866f47c72ba9f0a5819ae97334abf4843099d9c2 Mon Sep 17 00:00:00 2001
From: Timothy Fong <timmyoctoidea@gmail.com>
Date: Sun, 9 Jul 2023 19:48:55 -0400
Subject: [PATCH] added the core_vr_simulator to examples (#107)

---
 examples/core/core_vr_simulator.py | 100 +++++++++++++++++++++++++++++
 1 file changed, 100 insertions(+)
 create mode 100644 examples/core/core_vr_simulator.py

diff --git a/examples/core/core_vr_simulator.py b/examples/core/core_vr_simulator.py
new file mode 100644
index 0000000..f8cc6be
--- /dev/null
+++ b/examples/core/core_vr_simulator.py
@@ -0,0 +1,100 @@
+import pyray
+GLSL_VERSION = 330
+
+# Initialization
+screenWidth = 800
+screenHeight = 450
+
+# NOTE: screenWidth/screenHeight should match VR device aspect ratio
+pyray.init_window(screenWidth, screenHeight, "raylib [core] example - vr simulator")
+
+# VR device parameters definition
+device = pyray.VrDeviceInfo(
+    # Oculus Rift CV1 parameters for simulator
+    2160,                  # Horizontal resolution in pixels
+    1200,                  # Vertical resolution in pixels
+    0.133793,              # Horizontal size in meters
+    0.0669,                # Vertical size in meters
+    0.04678,             # Screen center in meters
+    0.041,         # Distance between eye and display in meters
+    0.07,       # Lens separation distance in meters
+    0.07,       # IPD (distance between pupils) in meters
+
+    # NOTE: CV1 uses fresnel-hybrid-asymmetric lenses with specific compute shaders
+    # Following parameters are just an approximation to CV1 distortion stereo rendering
+    [1.0, 0.22, 0.24, 0.0],     # Lens distortion constant parameters
+    [0.996, -0.004, 1.014, 0.0]   # Chromatic aberration correction parameters
+)
+
+# Load VR stereo config for VR device parameters (Oculus Rift CV1 parameters)
+config = pyray.load_vr_stereo_config(device)
+
+# Distortion shader (uses device lens distortion and chroma)
+distortion = pyray.load_shader(0, f"resources/distortion{GLSL_VERSION}.fs")
+
+# Update distortion shader with lens and distortion-scale parameters
+pyray.set_shader_value(distortion, 2,"leftLensCenter",  pyray.SHADER_UNIFORM_VEC2)
+pyray.set_shader_value(distortion, 2,"rightLensCenter",  pyray.SHADER_UNIFORM_VEC2)
+pyray.set_shader_value(distortion, 2,"leftScreenCenter",  pyray.SHADER_UNIFORM_VEC2)
+pyray.set_shader_value(distortion, 2,"rightScreenCenter",  pyray.SHADER_UNIFORM_VEC2)
+
+pyray.set_shader_value(distortion, 2,"scale",  pyray.SHADER_UNIFORM_VEC2)
+pyray.set_shader_value(distortion, 2,"scaleIn",  pyray.SHADER_UNIFORM_VEC2)
+pyray.set_shader_value(distortion, 4,"deviceWarpParam",  pyray.SHADER_UNIFORM_VEC4)
+pyray.set_shader_value(distortion, 4,"chromaAbParam",  pyray.SHADER_UNIFORM_VEC4)
+
+# Initialize framebuffer for stereo rendering
+# NOTE: Screen size should match HMD aspect ratio
+target = pyray.load_render_texture(device.hResolution, device.vResolution)
+
+# The target's height is flipped (in the source Rectangle), due to OpenGL reasons
+sourceRec = pyray.Rectangle(0.0, 0.0, target.texture.width, -target.texture.height)
+destRec = pyray.Rectangle(0.0, 0.0, pyray.get_screen_width(), pyray.get_screen_height())
+
+# Define the camera to look into our 3D world
+camera = pyray.Camera3D(
+    pyray.Vector3(5.0, 2.0, 5.0),    # Camera position
+    pyray.Vector3(0.0, 2.0, 0.0),      # Camera looking at point
+    pyray.Vector3(0.0, 1.0, 0.0),          # Camera up vector
+    60.0,                               # Camera field-of-view Y
+    pyray.CAMERA_PERSPECTIVE       # Camera projection type
+)
+
+cubePosition = pyray.Vector3(0.0, 0.0, 0.0)
+
+pyray.disable_cursor()                # Limit cursor to relative movement inside the window
+
+pyray.set_target_fps(90)              # Set our game to run at 90 frames-per-second
+
+# Main game loop
+while not pyray.window_should_close():     # Detect window close button or ESC key
+    # Update
+    pyray.update_camera(camera, pyray.CAMERA_FIRST_PERSON)
+
+    # Draw
+    pyray.begin_texture_mode(target)
+    pyray.clear_background(pyray.RAYWHITE)
+    pyray.begin_vr_stereo_mode(config)
+    pyray.begin_mode_3d(camera)
+
+    pyray.draw_cube(cubePosition, 2.0, 2.0, 2.0, pyray.RED)
+    pyray.draw_cube_wires(cubePosition, 2.0, 2.0, 2.0, pyray.MAROON)
+    pyray.draw_grid(40, 1.0)
+
+    pyray.end_mode_3d()
+    pyray.end_vr_stereo_mode()
+    pyray.end_texture_mode()
+
+    pyray.begin_drawing()
+    pyray.clear_background(pyray.RAYWHITE)
+    pyray.begin_shader_mode(distortion)
+    pyray.draw_texture_pro(target.texture, sourceRec, destRec, pyray.Vector2(0.0, 0.0), 0.0, pyray.WHITE)
+    pyray.end_shader_mode()
+    pyray.draw_fps(10, 10)
+    pyray.end_drawing()
+
+# De-Initialization
+pyray.unload_vr_stereo_config(config)   # Unload stereo config
+pyray.unload_render_texture(target)     # Unload stereo render fbo
+pyray.unload_shader(distortion)         # Unload distortion shader
+pyray.close_window()                    # Close window and OpenGL context