glOrtho(3G)glOrtho(3G)NAMEglOrtho - multiply the current matrix with an orthographic matrix
SYNOPSIS
void glOrtho(
GLdouble left,
GLdouble right,
GLdouble bottom,
GLdouble top,
GLdouble zNear,
GLdouble zFar );
PARAMETERS
Specify the coordinates for the left and right vertical clipping
planes. Specify the coordinates for the bottom and top horizontal
clipping planes. Specify the distances to the nearer and farther depth
clipping planes. These values are negative if the plane is to be behind
the viewer.
DESCRIPTIONglOrtho() describes a transformation that produces a parallel projec‐
tion. 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: 2 / right-left
0 0 t[x] 0 2 / top-bottom 0
t[y] 0 0 -2 / zFar - zNear t[z] 0
0 0 1
where t[x] = - right + left / right - left t[y] = - top + bottom / top
- bottom t[z] = zFar + zNear / zFar - zNear
Typically, the matrix mode is GL_PROJECTION, and (left, bottom,
-zNear) and (right, top, -zNear) specify the points on the near clip‐
ping 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). -zFar specifies the location of the far clipping plane. Both zNear
and zFar can be either positive or negative.
Use glPushMatrix() and glPopMatrix() to save and restore the current
matrix stack.
ERRORS
GL_INVALID_OPERATION is generated if glOrtho() is executed between the
execution of glBegin() and the corresponding execution of glEnd().
ASSOCIATED GETSglGet() 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
SEE ALSOglFrustum(3), glMatrixMode(3), glMultMatrix(3), glPushMatrix(3),
glViewport(3)glOrtho(3G)