c/render: Remove the hacks

src/xrt/compositor/render/comp_compute.c

@@ -141,15 +141,11 @@ calc_time_warp_matrix(struct comp_rendering_compute *crc,
 	// Src rotation matrix.
 	struct xrt_matrix_4x4_f64 src_rot_inv;
 	struct xrt_quat src_q = src_pose->orientation;
-	src_q.x = -src_q.x;                           // I don't know why we need to do this.
-	src_q.z = -src_q.z;                           // I don't know why we need to do this.
 	m_mat4_f64_orientation(&src_q, &src_rot_inv); // This is a model matrix, a inverted view matrix.
 
 	// New rotation matrix.
 	struct xrt_matrix_4x4_f64 new_rot, new_rot_inv;
 	struct xrt_quat new_q = new_pose->orientation;
-	new_q.x = -new_q.x;                           // I don't know why we need to do this.
-	new_q.z = -new_q.z;                           // I don't know why we need to do this.
 	m_mat4_f64_orientation(&new_q, &new_rot_inv); // This is a model matrix, a inverted view matrix.
 	m_mat4_f64_invert(&new_rot_inv, &new_rot);    // Invert to make it a view matrix.
 

src/xrt/compositor/shaders/distortion_timewarp.comp

@@ -43,6 +43,7 @@ vec2 transform_uv(vec2 uv, uint iz)
 
 	// From uv to tan angle (tanget space).
 	values.xy = values.xy * ubo.pre_transform[iz].zw + ubo.pre_transform[iz].xy;
+	values.y = -values.y; // Flip to OpenXR coordinate system.
 
 	// Timewarp.
 	values = ubo.transform[iz] * values;
@@ -50,6 +51,7 @@ vec2 transform_uv(vec2 uv, uint iz)
 
 	// From [-1, 1] to [0, 1]
 	values.xy = values.xy * 0.5 + 0.5;
+	values.y = 1 - values.y; // Flip to UV coordinate system.
 
 	// To deal with OpenGL flip and sub image view.
 	values.xy = values.xy * ubo.post_transform[iz].zw + ubo.post_transform[iz].xy;