Ycvtftop - Texas Instruments TI-89 Developer's Manual

Appendix A: System Routines — Graphing

YCvtFtoP

Declaration: SSHORT YCvtFtoP (BCD16 y , GR_WIN_VARS * ptr )
Category: Graphing
Description: Converts the input floating point y coordinate to a pixel row number based
on the specified graph viewing window.
y
Inputs:
ptr — Pointer to the GR_WIN_VARS struct to use for viewing window
Outputs: Returns a pixel row number or GXY_INVALID if the value computed is
outside the range of SSHORT. The topmost row in a window is row 0.
Assumptions: Assumes an x, y coordinate system, even in 3D mode.
Side Effects: None
Availability: All versions of the TI-89 / TI-92 Plus.
TI-89 / TI-92 Plus
Differences: None
See Also: XCvtPtoF, CptFuncX, YCvtPtoF, XCvtFtoP
Example:
/* convert float coordinates to pixel coordinates and plot point on the pixel */
col = XCvtFtoP( x, gr_active );
row = YCvtFtoP( y, gr_active );
WinPixSet( gr_active->grwinp, col, row );
TI-89 / TI-92 Plus Developer Guide
— Floating point y coordinate. Valid y is not limited to the actual
viewing window, allowing computation of off-screen pixels above
(negative) or below the visible window.
values (gr_active for the active graph window, gr_other for the
second graph in two graph mode).
/* find pixel column */
/* find pixel row */
Not for Distribution
/* plot point */
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Beta Version January 26, 2001