Calculate camera position together with players.

Keep the same lock during the calculation, so that the camera position
is consistent with player positions. Otherwise, they might not match
during one frame.

eX0-go/camera.go

@@ -39,19 +39,19 @@ type PlayerCamera struct {
 	pos playerPosVel
 }
 
+// CalculateForFrame calculates camera position for frame at gameMoment.
+// c.logic.playersStateMu must be held.
 func (c *PlayerCamera) CalculateForFrame(gameMoment gameMoment) {
-	c.logic.playersStateMu.Lock()
 	ps := c.logic.playersState[c.playerID]
 	if (ps.conn != nil && ps.conn.JoinStatus < IN_GAME) || ps.Team == packet.Spectator {
-		c.logic.playersStateMu.Unlock()
 		return
 	}
 	// TODO: Consider using same position as calculated for all players
 	//       during "Calculate player positions for this frame" step,
 	//       instead of our own copy (which might not match).
-	//       This is better now that we're using same gameMoment.
+	//       This is better now that we're using same gameMoment
+	//       and locking playersStateMu outside.
 	c.pos = ps.InterpolatedOrDead(gameMoment, c.playerID)
-	c.logic.playersStateMu.Unlock()
 }
 
 func (c *PlayerCamera) ModelView() mgl32.Mat4 {

eX0-go/view.go

@@ -147,10 +147,11 @@ func (v *view) initAndMainLoop() {
 
 		gl.Clear(gl.COLOR_BUFFER_BIT)
 
-		// Calculate player positions for this frame.
+		// Calculate camera and player positions for this frame.
 		var players []visiblePlayer
 		state.Lock()
 		v.logic.playersStateMu.Lock()
+		v.cameras[v.activeCamera].CalculateForFrame(gameMoment)
 		for id, ps := range v.logic.playersState {
 			if ps.conn != nil && ps.conn.JoinStatus < IN_GAME { // TODO: Fix JoinStatus race with line server.go:719.
 				continue
@@ -170,7 +171,6 @@ func (v *view) initAndMainLoop() {
 		v.logic.playersStateMu.Unlock()
 		state.Unlock()
 
-		v.cameras[v.activeCamera].CalculateForFrame(gameMoment)
 		pMatrix := mgl32.Ortho2D(0, float32(v.windowSize[0]), 0, float32(v.windowSize[1]))
 		mvMatrix := v.cameras[v.activeCamera].ModelView()