Method GL.glOrtho()

Method glOrtho

void glOrtho(float left, float right, float bottom, float top, float nearVal, float farVal)

Description

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:

(

2/right-left	0	0	t_x
0	2/top-bottom	0	t_y
0	0	-2/farVal-nearVal	t_z
0	0	0	1

)

where t_x=-right+left/right-left t_y=-top+bottom/top-bottom t_z=-farVal+nearVal/farVal-nearVal

Typically, the matrix mode is GL_PROJECTION, and (left, bottom, -nearVal) and (right, top, -nearVal) 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). -farVal specifies the location of the far clipping plane. Both nearVal and farVal can be either positive or negative.

Use glPushMatrix and glPopMatrix to save and restore the current matrix stack.

Parameter left

Parameter right

Specify the coordinates for the left and right vertical clipping planes.

Parameter bottom

Parameter top

Specify the coordinates for the bottom and top horizontal clipping planes.

Parameter nearVal

Parameter 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.

Throws

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.