GLORTHO(3G) UNIX Programmer's Manual GLORTHO(3G)
glOrtho - multiply the current matrix with an orthographic
matrix
void glOrtho( GLdouble left,
GLdouble right,
GLdouble bottom,
GLdouble top,
GLdouble near_val,
GLdouble far_val )
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.
near_val, far_val
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 multi-
plied by this matrix and the result replaces the current
matrix, as if glMultMatrix were called with the following
matrix as its argument:
|
|
|
|__________
|right-left 0
| 0
| 0 __________ |
| top-bottom 0 tx |
| 0 |
| 0 0 ________2________ ty |
0 far_val-near_val |
0 tz |
1 |
|
|
|
where _i__h___±__e__t_
tx = -t_o_p__t±_b__l_t_o_m_
ty f__-___v_a__-_±_o_e_a_r____a__l
tz = -far_val - near_val
MirOS BSD #10-current Printed 20.2.2012 1
GLORTHO(3G) UNIX Programmer's Manual GLORTHO(3G)
Typically, the matrix mode is GL_PROJECTION, and (left, bot-
tom, -near_val) and (right, top, -near_val) specify the
points on the near clipping plane that are mapped to the
lower left and upper right corners of the window, respec-
tively, assuming that the eye is located at (0, 0, 0).
-far_val specifies the location of the far clipping plane.
Both near_val and far_val can be either positive or nega-
tive.
Use glPushMatrix and glPopMatrix to save and restore the
current matrix stack.
GL_INVALID_OPERATION is generated if glOrtho is executed
between the execution of glBegin and the corresponding exe-
cution 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
glFrustum(3G), glMatrixMode(3G), glMultMatrix(3G),
glPushMatrix(3G), glViewport(3G)
MirOS BSD #10-current Printed 20.2.2012 2
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