WIP: more on Window.viewScale, .viewPos

with outline of a test

psychopy/tests/test_all_visual/flips.py

@@ -0,0 +1,26 @@
+# test window.viewScale and .viewPos simultaneous and negative-going values
+# the green square/rect should move clockwise around the text
+
+from psychopy import visual, event
+
+win = visual.Window(size=(400,400), units='pix')  #, viewOri=30)  test viewOri here
+
+v = [(1,1),(1,-1),(-1,-1),(-1,1)]  # vertices to use = square
+n = 30  # size of the square
+pimg= (n,n)  # position for the image
+pgrn = (-n,-n)  # position for green square
+
+for offset in [(0,0), (-.4,0)]:
+    win.viewPos = offset
+    for scale in [[1,1],  # normal: green at lower left
+                  [1,-1],  # mirror vert only: green appears to move up, text mirrored
+                  [-1,-1],  # mirror horiz & vert: green appears to move right, text normal but upside down
+                  [-1,1],  # mirror horiz only: green appears to move down, text mirrored
+            [2,2],[2,-2],[-2,-2],[-2,2]]:  # same, but both larger
+        win.viewScale = scale
+        grn = visual.ShapeStim(win, vertices=v, pos=pgrn, size=n, fillColor='darkgreen')
+        img = visual.ImageStim(win, image='s.png', pos=pimg)
+        grn.draw()
+        img.draw()
+        win.flip()
+        event.waitKeys()

psychopy/visual/window.py

@@ -609,15 +609,13 @@ def flip(self, clearBuffer=True):
                 if stencilOn:
                     GL.glEnable(GL.GL_STENCIL_TEST)
         #rescale/reposition view of the window
+        GL.glMatrixMode(GL.GL_MODELVIEW)
+        GL.glLoadIdentity()
         if self.viewScale is not None:
-            GL.glMatrixMode(GL.GL_PROJECTION)
-            GL.glLoadIdentity()
             GL.glOrtho(-1, 1, -1, 1, -1, 1)
             GL.glScalef(self.viewScale[0], self.viewScale[1], 1)
             scale = self.viewScale
         else:
-            GL.glMatrixMode(GL.GL_MODELVIEW)
-            GL.glLoadIdentity()
             scale = [1, 1]
 
         if self.viewPos is not None:
@@ -626,7 +624,13 @@ def flip(self, clearBuffer=True):
             GL.glTranslatef(norm_rf_pos_x, norm_rf_pos_y, 0.0)
 
         if self.viewOri is not None:
-            GL.glRotatef(self.viewOri, 0.0, 0.0, -1.0)
+            # the logic below for flip is partially correct, but does not handle viewPos
+            flip = 1
+            if self.viewScale is not None:
+                _f = self.viewScale[0] * self.viewScale[1]
+                if _f < 0:
+                    flip = -1
+            GL.glRotatef(flip * self.viewOri, 0.0, 0.0, -1.0)
 
         #reset returned buffer for next frame
         self._endOfFlip(clearBuffer)