Circular Fixation Point Stimulus¶
Width of the (circular) fixation window, which shares its center with the visible stimulus ellipse
Variable containing the horizontal eye position
Variable containing the vertical eye position
Variable to which fixation status is written. When the subject’s gaze (as reported by trigger_watch_x and trigger_watch_y) enters the fixation window, the variable is set to true. When the subject’s gaze leaves the fixation window, the variable is set to false.
Note: Fixation is reported only when the fixation point is on screen (i.e. after it has been queued and the display has been updated). If you need a hidden fixation point, set alpha_multiplier to zero.
The color of the stimulus, expressed as a comma-separated list of red, green, and blue components. Each component may be described by any valid expression, but the expression must result in a value between 0 and 1 (inclusive).
By default, the alpha multiplier controls the transparency of the
1.0 is fully opaque, while
0.0 is fully tranparent.
Source blending factor.
The parameters source_blend_factor, dest_blend_factor, source_alpha_blend_factor, and dest_alpha_blend_factor provide detailed control over how the color components and alpha multiplier of each fragment of the stimulus (the “source”) are combined with the color and alpha values already present in the framebuffer (the “destination”), which in turn result from blending the stimulus display background with any stimuli drawn beneath the source stimulus. These parameters correspond directly to the four arguments of the OpenGL function glBlendFuncSeparate. Please refer to that function’s reference page for explanations of the different blend factor options.
Note: Irrespective of the blend factors used, the blend equation
Destination blending factor. Accepts the same values as source_blend_factor.
Source alpha blending factor. Accepts the same values as source_blend_factor.
If omitted, the value of source_blend_factor is used.
Destination alpha blending factor. Accepts the same values as source_blend_factor.
If omitted, the value of dest_blend_factor is used.
Horizontal size (degrees).
Vertical size (degrees).
Horizontal center position (degrees)
Vertical center position (degrees)
Controls when the stimulus is loaded. If
no, the stimulus is loaded at experiment load time. If
yes, the stimulus is loaded the first time it is queued. If
explicit, the stimulus must be loaded explictly with Load Stimulus.
Name of the display on which the stimulus will be presented. If omitted, the default display (if available) will be used.
Allowed at top level: