glOrtho — multiply the current matrix with an orthographic matrix
void glOrtho( | GLdouble left, |
GLdouble right, | |
GLdouble bottom, | |
GLdouble top, | |
GLdouble nearVal, | |
GLdouble farVal) ; |
left
, right
Specify the coordinates for the left and right vertical clipping planes.
bottom
, top
Specify the coordinates for the bottom and top horizontal clipping planes.
nearVal
, farVal
Specify the distances to the nearer and farther depth clipping planes. These values are negative if the plane is to be behind the viewer.
glOrtho
describes a transformation that produces a parallel projection.
The current matrix (see glMatrixMode) is multiplied by this matrix
and the result replaces the current matrix, as if
glMultMatrix were called with the following matrix
as its argument:
where
Typically, the matrix mode is GL_PROJECTION
, and
nearVal
and farVal
can be either positive or negative.
Use glPushMatrix and glPopMatrix to save and restore the current matrix stack.
GL_INVALID_VALUE
is generated if
left
= right
, or
bottom
= top
, or
near
= far
.
GL_INVALID_OPERATION
is generated if glOrtho
is executed between the execution of
glBegin
and the corresponding execution of glEnd.
glGet with argument GL_MATRIX_MODE
glGet with argument GL_COLOR_MATRIX
glGet with argument GL_MODELVIEW_MATRIX
glGet with argument GL_PROJECTION_MATRIX
glGet with argument GL_TEXTURE_MATRIX
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