glOrtho
[New
- Windows 95, OEM Service Release 2]
The glOrtho
function multiplies the current matrix by an orthographic matrix.
void glOrtho(
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GLdouble left, |
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GLdouble right, |
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GLdouble bottom, |
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GLdouble top, |
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GLdouble near, |
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GLdouble far |
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); |
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Parameters
left,
right
The
coordinates for the left and right vertical clipping planes.
bottom,
top
The
coordinates for the bottom and top horizontal clipping planes.
near,
far
The distances
to the nearer and farther depth clipping planes. These distances are negative
if the plane is to be behind the viewer.
Remarks
The glOrtho
function describes a perspective matrix that produces a parallel projection.
The (left, bottom, - near) and (right, top, - near) parameters specify the points on the
near clipping plane that are mapped to the lower-left and upper-right corners
of the window, respectively, assuming that the eye is located at (0, 0, 0). The
-far parameter specifies the location of the far clipping
plane. Both near and far can be either positive or negative. The
corresponding matrix is
{bml bm47.BMP}
where
{bml bm48.BMP}
The current
matrix is multiplied by this matrix with the result replacing the current
matrix. That is, if M is the current matrix and O is the ortho matrix, then M
is replaced with M O.
Use glPushMatrix and glPopMatrix to
save and restore the current matrix stack.
The following
functions retrieve information related to glOrtho:
glGet
with argument GL_MATRIX_MODE
glGet with
argument GL_MODELVIEW_MATRIX
glGet with
argument GL_PROJECTION_MATRIX
glGet with
argument GL_TEXTURE_MATRIX
Error Codes
The following
are the error codes generated and their conditions.
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Error
Code |
Condition |
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GL_INVALID_OPERATION
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glOrtho was called between a call to glBegin and the
corresponding call to glEnd. |
See Also