Added custom Oculus CV1 parameters

Matching the same stereo rendering result given by Oculus PC SDK for
Oculus Rift CV1 is very difficult because hardware has changed a lot and
DK2 distortion shader and parameters don't fit on CV1. Some custom
parameters have been calculated to simulate kind of CV1 stereo
rendering. Further work is required on this point.

examples/core_oculus_rift.c

@@ -18,8 +18,10 @@ int main()
 {
     // Initialization
     //--------------------------------------------------------------------------------------
-    int screenWidth = 1280;
-    int screenHeight = 800;
+    int screenWidth = 1080;
+    int screenHeight = 600;
+    
+    // NOTE: screenWidth/screenHeight should match VR device aspect ratio
     
     InitWindow(screenWidth, screenHeight, "raylib [core] example - oculus rift");
     

src/rlgl.c

@@ -2570,38 +2570,62 @@ void InitVrDevice(int hmdDevice)
 
     if (!vrDeviceReady)
     {
-        TraceLog(WARNING, "VR Device not found: Initializing VR Simulator (Oculus Rift DK2)");
+        TraceLog(WARNING, "VR Device not found: Initializing VR Simulator (Oculus Rift CV1)");
 
+        if (hmdDevice == HMD_OCULUS_RIFT_DK2)
+        {
+            // Oculus Rift DK2 parameters
+            hmd.hResolution = 1280;                 // HMD horizontal resolution in pixels
+            hmd.vResolution = 800;                  // HMD vertical resolution in pixels
+            hmd.hScreenSize = 0.14976f;             // HMD horizontal size in meters
+            hmd.vScreenSize = 0.09356f;             // 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 = 0.0635f;   // HMD lens separation distance in meters
+            hmd.interpupillaryDistance = 0.064f;    // HMD IPD (distance between pupils) in meters
+            hmd.distortionK[0] = 1.0f;              // HMD lens distortion constant parameter 0
+            hmd.distortionK[1] = 0.22f;             // HMD lens distortion constant parameter 1
+            hmd.distortionK[2] = 0.24f;             // HMD lens distortion constant parameter 2
+            hmd.distortionK[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
+        }
+        else if ((hmdDevice == HMD_DEFAULT_DEVICE) || (hmdDevice == HMD_OCULUS_RIFT_CV1))
+        {
+            // Oculus Rift CV1 parameters
+            // NOTE: CV1 represents a complete HMD redesign compared to previous versions,
+            // new Fresnel-hybrid-asymmetric lenses have been added and, consequently, 
+            // previous parameters (DK2) and distortion shader (DK2) doesn't work any more. 
+            // I just defined a set of parameters for simulator that approximate to CV1 stereo rendering 
+            // but result is not the same obtained with Oculus PC SDK.
+            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 = 0.0669;               // 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
+            hmd.distortionK[0] = 1.0f;              // HMD lens distortion constant parameter 0
+            hmd.distortionK[1] = 0.22f;             // HMD lens distortion constant parameter 1
+            hmd.distortionK[2] = 0.24f;             // HMD lens distortion constant parameter 2
+            hmd.distortionK[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
+        }
+        
         // Initialize framebuffer and textures for stereo rendering
+        // NOTE: screen size should match HMD aspect ratio
         vrConfig.stereoFbo = rlglLoadRenderTexture(screenWidth, screenHeight);
         
         // Load distortion shader (initialized by default with Oculus Rift CV1 parameters)
         vrConfig.distortionShader.id = LoadShaderProgram(vDistortionShaderStr, fDistortionShaderStr);
         if (vrConfig.distortionShader.id != 0) LoadDefaultShaderLocations(&vrConfig.distortionShader);
 
-        if ((hmdDevice == HMD_DEFAULT_DEVICE) || 
-            (hmdDevice == HMD_OCULUS_RIFT_DK2) || 
-            (hmdDevice == HMD_OCULUS_RIFT_CV1))
-        {
-            // NOTE: Oculus Rift DK2 parameters
-            hmd.hResolution = 1280;                // HMD horizontal resolution in pixels
-            hmd.vResolution = 800;                 // HMD vertical resolution in pixels
-            hmd.hScreenSize = 0.14976f;;           // HMD horizontal size in meters
-            hmd.vScreenSize = 0.09356f;            // HMD vertical size in meters
-            hmd.vScreenCenter = 0.04675f;          // HMD screen center in meters
-            hmd.eyeToScreenDistance = 0.041f;      // HMD distance between eye and display in meters
-            hmd.lensSeparationDistance = 0.0635f;  // HMD lens separation distance in meters
-            hmd.interpupillaryDistance = 0.064f;   // HMD IPD (distance between pupils) in meters
-            hmd.distortionK[0] = 1.0f;             // HMD lens distortion constant parameter 0
-            hmd.distortionK[1] = 0.22f;            // HMD lens distortion constant parameter 1
-            hmd.distortionK[2] = 0.24f;            // HMD lens distortion constant parameter 2
-            hmd.distortionK[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
-        }
-
         SetStereoConfig(hmd);
         
         vrSimulator = true;
@@ -3761,9 +3785,8 @@ static Color *GenNextMipmap(Color *srcData, int srcWidth, int srcHeight)
 static void SetStereoConfig(VrDeviceInfo hmd)
 {
     // Compute aspect ratio
-    //float aspect = ((float)hmd.hResolution*0.5f)/(float)hmd.vResolution;
-    float aspect = (float)screenWidth*0.5f/(float)screenHeight;
-    
+    float aspect = ((float)hmd.hResolution*0.5f)/(float)hmd.vResolution;
+
     // Compute lens parameters
     float lensShift = (hmd.hScreenSize*0.25f - hmd.lensSeparationDistance*0.5f)/hmd.hScreenSize;
     float leftLensCenter[2] = { 0.25 + lensShift, 0.5f };
@@ -3779,12 +3802,19 @@ static void SetStereoConfig(VrDeviceInfo hmd)
                             hmd.distortionK[1]*lensRadiusSq + 
                             hmd.distortionK[2]*lensRadiusSq*lensRadiusSq + 
                             hmd.distortionK[3]*lensRadiusSq*lensRadiusSq*lensRadiusSq;
-
+    
+    TraceLog(DEBUG, "VR: Distortion Scale: %f", distortionScale);
+    
     float normScreenWidth = 0.5f;
     float normScreenHeight = 1.0f;
     float scaleIn[2] = { 2/normScreenWidth, 2/normScreenHeight/aspect };
     float scale[2] = { normScreenWidth*0.5/distortionScale, normScreenHeight*0.5*aspect/distortionScale };
     
+    TraceLog(DEBUG, "VR: Distortion Shader: LeftLensCenter = { %f, %f }", leftLensCenter[0], leftLensCenter[1]);
+    TraceLog(DEBUG, "VR: Distortion Shader: RightLensCenter = { %f, %f }", rightLensCenter[0], rightLensCenter[1]);
+    TraceLog(DEBUG, "VR: Distortion Shader: Scale = { %f, %f }", scale[0], scale[1]);
+    TraceLog(DEBUG, "VR: Distortion Shader: ScaleIn = { %f, %f }", scaleIn[0], scaleIn[1]);
+    
     // Update distortion shader with lens and distortion-scale parameters
     SetShaderValue(vrConfig.distortionShader, GetShaderLocation(vrConfig.distortionShader, "leftLensCenter"), leftLensCenter, 2);
     SetShaderValue(vrConfig.distortionShader, GetShaderLocation(vrConfig.distortionShader, "rightLensCenter"), rightLensCenter, 2);
@@ -3798,8 +3828,9 @@ static void SetStereoConfig(VrDeviceInfo hmd)
 
     // Fovy is normally computed with: 2*atan2(hmd.vScreenSize, 2*hmd.eyeToScreenDistance)*RAD2DEG
     // ...but with lens distortion it is increased (see Oculus SDK Documentation)
-    float fovy = 2.0f*atan2(hmd.vScreenSize*0.5f*distortionScale, hmd.eyeToScreenDistance)*RAD2DEG;     // Really need distortionScale?
-
+    //float fovy = 2.0f*atan2(hmd.vScreenSize*0.5f*distortionScale, hmd.eyeToScreenDistance)*RAD2DEG;     // Really need distortionScale?
+    float fovy = 2.0f*atan2(hmd.vScreenSize*0.5f, hmd.eyeToScreenDistance)*RAD2DEG;
+    
     // Compute camera projection matrices
     float projOffset = 4.0f*lensShift;      // Scaled to projection space coordinates [-1..1]
     Matrix proj = MatrixPerspective(fovy, aspect, 0.01, 1000.0);
@@ -3820,9 +3851,6 @@ static void SetStereoConfig(VrDeviceInfo hmd)
     // Compute eyes Viewports
     //vrConfig.eyesViewport[0] = (Rectangle){ 0, 0, hmd.hResolution/2, hmd.vResolution };
     //vrConfig.eyesViewport[1] = (Rectangle){ hmd.hResolution/2, 0, hmd.hResolution/2, hmd.vResolution };
-    
-    //https://forums.oculus.com/vip/discussion/3413/calculating-the-distortion-shader-parameters
-    //https://vrwiki.wikispaces.com/Theory+%26+practice
 }
 
 // Set internal projection and modelview matrix depending on eyes tracking data