step 1: find the vertex shader of your shader (I will be using SCSS as an example)

in SCSS the vertex shader is on line 6 in SCSS_Forward.cginc

this is what it looks like

VertexOutput vert(appdata_full v) {
	VertexOutput o = (VertexOutput)0;

    UNITY_SETUP_INSTANCE_ID(v);
    UNITY_INITIALIZE_OUTPUT(VertexOutput, o);
    UNITY_TRANSFER_INSTANCE_ID(v, o);
    UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(o);
...
}





Step 2: paste the functions I included at the bottom before the vertex shader (so in front of the VertexOutput vert(...))




Step 3:
now if we wanted something to only display in VR we modify that to this.

VertexOutput vert(appdata_full v) {
	VertexOutput o = (VertexOutput)0;

	if(!isVR()){
		return o;
	}

    UNITY_SETUP_INSTANCE_ID(v);
    UNITY_INITIALIZE_OUTPUT(VertexOutput, o);
    UNITY_TRANSFER_INSTANCE_ID(v, o);
    UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(o);
...
}

this will make the gpu discard all triangles if it's not in vr









//this needs to match your camera_res_height in the config.json file
#define VRC_CONFIG_CAMERA_RESOLUTION 2160

bool isVR()
{
	// USING_STEREO_MATRICES
	#if UNITY_SINGLE_PASS_STEREO
	return true;
	#else
	return false;
	#endif
}

//UNITY_MATRIX_P._13 < 0 left eye, UNITY_MATRIX_P._13 > 0 right eye & UNITY_MATRIX_P._13 == 0 not vr
bool isLeftEye()
{
	return UNITY_MATRIX_P._13 < 0;
}

bool isRightEye()
{
	return UNITY_MATRIX_P._13 > 0;
}

bool isNotVr()
{
	return UNITY_MATRIX_P._13 == 0;
}

bool isOrtho()
{
	return unity_OrthoParams.w == 1 || UNITY_MATRIX_P[3][3] == 1;
}

float verticalFOV()
{
	return 2.0 * atan(1.0 / unity_CameraProjection._m11) * 180.0 / UNITY_PI;
}

// this checks if the shader is being rendered by a reflection probe
// I don't know how check for box projection if that's even possible
bool isReflectionProbe()
{
	return UNITY_MATRIX_P[0][0] == 1 && unity_CameraProjection._m11 == 1;
}

bool isVRHandCamera()
{
	return !isVR() && abs(UNITY_MATRIX_V[0].y) > 0.0000005;
}

bool isDesktop()
{
	return !isVR() && abs(UNITY_MATRIX_V[0].y) < 0.0000005;
}

bool isVRHandCameraPreview()
{
	return isVRHandCamera() && _ScreenParams.y == 720;
}

bool isVRHandCameraPicture()
{
	return isVRHandCamera() && _ScreenParams.y == VRC_CONFIG_CAMERA_RESOLUTION;
}

bool isVRHandCameraPictureAnyResolution()
{
	if (_ScreenParams.y == 1080 || _ScreenParams.y == 2160 || _ScreenParams.y == 1440 || _ScreenParams.y == 720)
	{
		return isVRHandCamera();
	}
	return false;
}

bool isPanorama()
{
	// Crude method
	// FOV=90=camproj=[1][1]
	return unity_CameraProjection[1][1] == 1 && _ScreenParams.x == 1075 && _ScreenParams.y == 1025;
}