MTXLightOrtho

Syntax

#include <revolution/mtx.h>

void MTXLightOrtho(
    Mtx m,
    f32 t,
    f32 b,
    f32 l,
    f32 r,
    f32 scaleS,
    f32 scaleT,
    f32 transS,
    f32 transT );

Arguments

`m`	New 3x4 parallel projection matrix. The type of m may be either `Mtx` or `MtxPtr`.
t	Top edge of view volume.
`b`	Bottom edge of view volume.
l	Left edge of view volume.
r	Right edge of view volume.
scaleS	Scale in the S direction for projected coordinates (usually 0.5)
scaleT	Scale in the T direction for projected coordinates (usually 0.5)
transS	Translation in the S direction for projected coordinates (usually 0.5)
transT	Translation in the T direction for projected coordinates (usually 0.5)

Return Values

None.

Description

Sets a 3x4 matrix for orthographic projection. This matrix is used to project points into texture space and yield texture coordinates.

For normal parallel projections, the -z axis is the axis of projection, so t is positive, b is -t, r is positive, and l is -r.

Standard projection yields values ranging from -1.0 to 1.0 in both dimensions of the front clipping plane. Since texture coordinates should usually be within the range of 0.0 to 1.0, we have added a scale and translation value for both S and T. The most common way to use these values is to set all of them to 0.5 (so that points in the range of -1.0 to 1.0 are first scaled by 0.5) to be in the range of -0.5 to 0.5. Then they are translated by 0.5 to be in the range of 0.0 to 1.0. Other values can be used for translation and scale to yield different effects.

Revision History

2006/03/01 Initial version.