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package ru.olamedia.camera;
import org.openmali.FastMath;
import org.openmali.vecmath2.Matrix4f;
public class CameraProjectionMatrix extends Matrix4f {
/**
* Creates a mesa-style perspective projection transform, that mimics a
* standard, camera-based, view-model.
*
* @param fovy
* specifies the field of view in the y direction, in radians
* @param aspect
* specifies the aspect ratio and thus the field of view in the x
* direction. The aspect ratio is the ratio of x to y, or width
* to height.
* @param zNear
* the distance to the frustum's near clipping plane. This value
* must be positive, (the value -zNear is the location of the
* near clip plane).
* @param zFar
* the distance to the frustum's far clipping plane.
*/
public final void perspectiveMesa(float fovy, float aspect, float zNear,
float zFar) {
final float ymax = zNear * FastMath.tan(fovy);
final float ymin = -ymax;
final float xmin = ymin * aspect;
final float xmax = ymax * aspect;
// don't call glFrustum() because of error semantics (covglu)
frustumMesa(xmin, xmax, ymin, ymax, zNear, zFar);
}
/**
* Creates a masa-style perspective projection transform, that mimics a
* standard, camera-based, view-model. The frustum function-call establishes
* a view-model with the eye at the apex of a symmetric view frustum. The
* arguments define the frustum and its associated perspective projection:
* (left, bottom, -near) and (right, top, -near) specify the point on the
* near clipping plane that maps onto the lower-left and upper-right corners
* of the window respectively, assuming the eye is located at (0, 0, 0).
*
* @param left
* the vertical line on the left edge of the near clipping plane
* mapped to the left edge of the graphics window
* @param right
* the vertical line on the right edge of the near clipping plane
* mapped to the right edge of the graphics window
* @param bottom
* the horizontal line on the bottom edge of the near clipping
* plane mapped to the bottom edge of the graphics window
* @param top
* the horizontal line on the top edge of the near
* @param zNear
* the distance to the frustum's near clipping plane. This value
* must be positive, (the value -near is the location of the near
* clip plane).
* @param zFar
* the distance to the frustum's far clipping plane. This value
* must be positive, and must be greater than near.
*/
public final void frustumMesa(float left, float right, float bottom,
float top, float zNear, float zFar) {
final float x = (2.0f * zNear) / (right - left);
final float y = (2.0f * zNear) / (top - bottom);
final float a = (right + left) / (right - left);
final float b = (top + bottom) / (top - bottom);
final float c = -(zFar + zNear) / (zFar - zNear);
final float d = -(2.0f * zFar * zNear) / (zFar - zNear);
this.set(x, 0f, 0f, 0f, 0f, y, 0f, 0f, a, b, c, -1f, 0f, 0f, d, 0f);
}
}
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