Review VR simulator mechanism

- No default VR device parameteres inside raylib
- VR device parameter should be provided by user
- VR distortion shader should be provided by user

examples/core/core_vr_simulator.c

@@ -23,7 +23,35 @@ int main()
     InitWindow(screenWidth, screenHeight, "raylib [core] example - vr simulator");
 
     // Init VR simulator (Oculus Rift CV1 parameters)
-    InitVrSimulator(GetVrDeviceInfo(HMD_OCULUS_RIFT_CV1));
+    InitVrSimulator();
+
+    VrDeviceInfo hmd = { 0 };               // VR device parameters (head-mounted-device)
+
+    // Oculus Rift CV1 parameters for simulator
+    hmd.hResolution = 2160;                 // HMD horizontal resolution in pixels
+    hmd.vResolution = 1200;                 // HMD vertical resolution in pixels
+    hmd.hScreenSize = 0.133793f;            // HMD horizontal size in meters
+    hmd.vScreenSize = 0.0669f;              // HMD vertical size in meters
+    hmd.vScreenCenter = 0.04678f;           // HMD screen center in meters
+    hmd.eyeToScreenDistance = 0.041f;       // HMD distance between eye and display in meters
+    hmd.lensSeparationDistance = 0.07f;     // HMD lens separation distance in meters
+    hmd.interpupillaryDistance = 0.07f;     // HMD IPD (distance between pupils) in meters
+
+    // NOTE: CV1 uses a Fresnel-hybrid-asymmetric lenses with specific distortion compute shaders.
+    // Following parameters are an approximation to distortion stereo rendering but results differ from actual device.
+    hmd.lensDistortionValues[0] = 1.0f;     // HMD lens distortion constant parameter 0
+    hmd.lensDistortionValues[1] = 0.22f;    // HMD lens distortion constant parameter 1
+    hmd.lensDistortionValues[2] = 0.24f;    // HMD lens distortion constant parameter 2
+    hmd.lensDistortionValues[3] = 0.0f;     // HMD lens distortion constant parameter 3
+    hmd.chromaAbCorrection[0] = 0.996f;     // HMD chromatic aberration correction parameter 0
+    hmd.chromaAbCorrection[1] = -0.004f;    // HMD chromatic aberration correction parameter 1
+    hmd.chromaAbCorrection[2] = 1.014f;     // HMD chromatic aberration correction parameter 2
+    hmd.chromaAbCorrection[3] = 0.0f;       // HMD chromatic aberration correction parameter 3
+
+    // Distortion shader (uses device lens distortion and chroma)
+    Shader distortion = LoadShader(0, "resources/distortion.fs");
+
+    SetVrConfiguration(hmd, distortion);    // Set Vr device parameters for stereo rendering
 
     // Define the camera to look into our 3d world
     Camera camera;
@@ -77,9 +105,11 @@ int main()
 
     // De-Initialization
     //--------------------------------------------------------------------------------------
-    CloseVrSimulator();     // Close VR simulator
-
-    CloseWindow();          // Close window and OpenGL context
+    UnloadShader(distortion);   // Unload distortion shader
+
+    CloseVrSimulator();         // Close VR simulator
+
+    CloseWindow();              // Close window and OpenGL context
     //--------------------------------------------------------------------------------------
 
     return 0;

examples/core/resources/distortion.fs

@@ -0,0 +1,43 @@
+#version 330
+
+in vec2 fragTexCoord;
+in vec4 fragColor;
+out vec4 finalColor;
+
+uniform sampler2D texture0;
+uniform vec2 leftLensCenter = vec2(0.288, 0.5);
+uniform vec2 rightLensCenter = vec2(0.712, 0.5);
+uniform vec2 leftScreenCenter = vec2(0.25, 0.5);
+uniform vec2 rightScreenCenter = vec2(0.75, 0.5);
+uniform vec2 scale = vec2(0.25, 0.45);
+uniform vec2 scaleIn = vec2(4, 2.2222);
+uniform vec4 hmdWarpParam = vec4(1, 0.22, 0.24, 0);
+uniform vec4 chromaAbParam = vec4(0.996, -0.004, 1.014, 0.0);
+
+void main()
+{
+    vec2 lensCenter = fragTexCoord.x < 0.5? leftLensCenter : rightLensCenter;
+    vec2 screenCenter = fragTexCoord.x < 0.5? leftScreenCenter : rightScreenCenter;
+    vec2 theta = (fragTexCoord - lensCenter)*scaleIn;
+    float rSq = theta.x*theta.x + theta.y*theta.y;
+    vec2 theta1 = theta*(hmdWarpParam.x + hmdWarpParam.y*rSq + hmdWarpParam.z*rSq*rSq + hmdWarpParam.w*rSq*rSq*rSq);
+    vec2 thetaBlue = theta1*(chromaAbParam.z + chromaAbParam.w*rSq);
+    vec2 tcBlue = lensCenter + scale*thetaBlue;
+
+    if (any(bvec2(clamp(tcBlue, screenCenter - vec2(0.25, 0.5), screenCenter + vec2(0.25, 0.5)) - tcBlue)))
+    {
+        finalColor = vec4(0.0, 0.0, 0.0, 1.0);
+    }
+    else
+    {
+        float blue = texture(texture0, tcBlue).b;
+        vec2 tcGreen = lensCenter + scale*theta1;
+        float green = texture(texture0, tcGreen).g;
+
+        vec2 thetaRed = theta1*(chromaAbParam.x + chromaAbParam.y*rSq);
+        vec2 tcRed = lensCenter + scale*thetaRed;
+
+        float red = texture(texture0, tcRed).r;
+        finalColor = vec4(red, green, blue, 1.0);
+    }
+};

src/config.h

@@ -57,8 +57,6 @@
 //------------------------------------------------------------------------------------
 // Support VR simulation functionality (stereo rendering)
 #define SUPPORT_VR_SIMULATOR        1
-// Include stereo rendering distortion shader (shader_distortion.h)
-#define SUPPORT_DISTORTION_SHADER   1
 
 
 //------------------------------------------------------------------------------------

src/raylib.h

@@ -443,16 +443,6 @@ typedef struct VrDeviceInfo {
     float chromaAbCorrection[4];    // HMD chromatic aberration correction parameters
 } VrDeviceInfo;
 
-// VR Stereo rendering configuration for simulator
-typedef struct VrStereoConfig {
-    RenderTexture2D stereoFbo;      // VR stereo rendering framebuffer
-    Shader distortionShader;        // VR stereo rendering distortion shader
-    Matrix eyesProjection[2];       // VR stereo rendering eyes projection matrices
-    Matrix eyesViewOffset[2];       // VR stereo rendering eyes view offset matrices
-    int eyeViewportRight[4];        // VR stereo rendering right eye viewport [x, y, w, h]
-    int eyeViewportLeft[4];         // VR stereo rendering left eye viewport [x, y, w, h]
-} VrStereoConfig;
-
 //----------------------------------------------------------------------------------
 // Enumerators Definition
 //----------------------------------------------------------------------------------
@@ -860,16 +850,6 @@ typedef enum {
     CAMERA_ORTHOGRAPHIC
 } CameraType;
 
-// Head Mounted Display devices
-typedef enum {
-    HMD_DEFAULT_DEVICE = 0,
-    HMD_OCULUS_RIFT_DK2,
-    HMD_OCULUS_RIFT_CV1,
-    HMD_OCULUS_GO,
-    HMD_VALVE_HTC_VIVE,
-    HMD_SONY_PSVR
-} VrDeviceType;
-
 // Type of n-patch
 typedef enum {
     NPT_9PATCH = 0,         // Npatch defined by 3x3 tiles
@@ -1330,7 +1310,7 @@ RLAPI Shader GetShaderDefault(void);                                      // Get
 RLAPI Texture2D GetTextureDefault(void);                                  // Get default texture
 
 // Shader configuration functions
-RLAPI int GetShaderLocation(Shader shader, const char *uniformName);              // Get shader uniform location
+RLAPI int GetShaderLocation(Shader shader, const char *uniformName);      // Get shader uniform location
 RLAPI void SetShaderValue(Shader shader, int uniformLoc, const void *value, int uniformType);               // Set shader uniform value
 RLAPI void SetShaderValueV(Shader shader, int uniformLoc, const void *value, int uniformType, int count);   // Set shader uniform value vector
 RLAPI void SetShaderValueMatrix(Shader shader, int uniformLoc, Matrix mat);         // Set shader uniform value (matrix 4x4)
@@ -1344,7 +1324,7 @@ RLAPI Matrix GetMatrixModelview();                                        // Get
 RLAPI Texture2D GenTextureCubemap(Shader shader, Texture2D skyHDR, int size);       // Generate cubemap texture from HDR texture
 RLAPI Texture2D GenTextureIrradiance(Shader shader, Texture2D cubemap, int size);   // Generate irradiance texture using cubemap data
 RLAPI Texture2D GenTexturePrefilter(Shader shader, Texture2D cubemap, int size);    // Generate prefilter texture using cubemap data
-RLAPI Texture2D GenTextureBRDF(Shader shader, int size);                  // Generate BRDF texture using cubemap data
+RLAPI Texture2D GenTextureBRDF(Shader shader, int size);                  // Generate BRDF texture
 
 // Shading begin/end functions
 RLAPI void BeginShaderMode(Shader shader);                                // Begin custom shader drawing
@@ -1355,10 +1335,10 @@ RLAPI void BeginScissorMode(int x, int y, int width, int height);         // Beg
 RLAPI void EndScissorMode(void);                                          // End scissor mode
 
 // VR control functions
-RLAPI VrDeviceInfo GetVrDeviceInfo(int vrDeviceType);   // Get VR device information for some standard devices
-RLAPI void InitVrSimulator(VrDeviceInfo info);          // Init VR simulator for selected device parameters
-RLAPI void UpdateVrTracking(Camera *camera);            // Update VR tracking (position and orientation) and camera
+RLAPI void InitVrSimulator(void);                       // Init VR simulator for selected device parameters
 RLAPI void CloseVrSimulator(void);                      // Close VR simulator for current device
+RLAPI void UpdateVrTracking(Camera *camera);            // Update VR tracking (position and orientation) and camera
+RLAPI void SetVrConfiguration(VrDeviceInfo info, Shader distortion);      // Set stereo rendering configuration parameters 
 RLAPI bool IsVrSimulatorReady(void);                    // Detect if VR simulator is ready
 RLAPI void ToggleVrMode(void);                          // Enable/Disable VR experience
 RLAPI void BeginVrDrawing(void);                        // Begin VR simulator stereo rendering