gSPViewPort

Syntax

#include <ultra64.h> /* gbi.h */
gSPViewport(Gfx *gdl, Vp *v)
gsSPViewport(Vp *v)

Arguments

• gdl is the display list pointer.

• v is the segment address to the viewport structure "Vp".

• vscale is the scale applied to the normalized homogeneous coordinates after 4x4 projection transformation.

• vtrans is the offset added to the scaled value.

Explanation
Sets the viewport area. The viewport structure elements have a 2-bit fraction required for scaling to sub-pixel positions. This can be used to handle the fraction values in the viewport.

vscale,vtrans are the screen coordinates. The array indices 0, 1, 2 correspond to x, y, z, while array index 3 is used for the alignment.

The viewport is the area the image occupies on the screen. For details, see Section 3-3-4, "The View Coordinate System" in Step 3 of the Kantan Manual.

Comment
The Vp structure is shown below:

typedef struct {
        short vscale[4];	/* Scale, 14.2 */
        short vtrans[4];	/* Transformation, 14.2 */
} Vp_t;
typedef union {
        Vp_t vp;
        long long int force_structure_alignment;
} Vp;

See Also
gDPSetScissor

Revision History
2/1/1999 Completely rewritten.

Nintendo® Confidential Warning: all information in this document is confidential and covered by a non-disclosure agreement. You are responsible for keeping this information confidential and protected. Nintendo will vigorously enforce this responsibility. Copyright © 1998 Nintendo of America Inc. All rights reserved Nintendo and N64 are registered trademarks of Nintendo Last updated March 1999