GLClippingPlanes.java
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/*
* This file is part of LiteLoader.
* Copyright (C) 2012-16 Adam Mummery-Smith
* All Rights Reserved.
*/
package com.mumfrey.liteloader.gl;
import static org.lwjgl.opengl.GL11.*;
import java.nio.DoubleBuffer;
import org.lwjgl.BufferUtils;
import org.lwjgl.util.Rectangle;
/**
* OpenGL clipping plane convenience functions. We prefer to clip rectangular
* GUI regions in Minecraft using clipping rather than scissor because scissor
* is a nuisance to work with, primarily because it works in "window" (OpenGL
* window) coordinates and doesn't respect the current transformation matrix.
* Using clipping planes we can specify clipping edges in "Minecraft screen
* coordinates", can optionally clip on only one or two axes, and also don't
* need to worry about the current transform.
*
* @author Adam Mummery-Smith
*/
public final class GLClippingPlanes
{
public enum Plane
{
LEFT(GL_CLIP_PLANE0),
RIGHT(GL_CLIP_PLANE1),
TOP(GL_CLIP_PLANE2),
BOTTOM(GL_CLIP_PLANE3);
final int plane;
final int sign;
private Plane(int plane)
{
this.plane = plane;
this.sign = (plane % 2 == 0) ? -1 : 1;
}
}
private static final int STACK_DEPTH = 1;
private static final int STACK_FRAME_SIZE = 128;
private static DoubleBuffer doubleBuffer = BufferUtils.createByteBuffer(STACK_FRAME_SIZE * STACK_DEPTH).asDoubleBuffer();
private static int clippingPlaneFlags = 0;
private static int totalClippingPlanes = glGetInteger(GL_MAX_CLIP_PLANES);
// private static int frame = 0;
static
{
for (int f = 0; f < STACK_DEPTH; f++)
{
// Clipping normals
GLClippingPlanes.doubleBuffer.put(1).put(0).put(0).put(0);
GLClippingPlanes.doubleBuffer.put(-1).put(0).put(0).put(0);
GLClippingPlanes.doubleBuffer.put(0).put(1).put(0).put(0);
GLClippingPlanes.doubleBuffer.put(0).put(-1).put(0).put(0);
}
}
private GLClippingPlanes() {}
/**
* Get the total number of available clipping planes on the platform
*/
public static int glGetTotalClippingPlanes()
{
return GLClippingPlanes.totalClippingPlanes;
}
/**
* Enable OpenGL clipping planes (uses planes 0, 1, 2 and 3)
*
* @param left Left edge clip or -1 to not use this plane
* @param right Right edge clip or -1 to not use this plane
* @param top Top edge clip or -1 to not use this plane
* @param bottom Bottom edge clip or -1 to not use this plane
*/
public static void glEnableClipping(int left, int right, int top, int bottom)
{
GLClippingPlanes.clippingPlaneFlags = 0;
glEnableClipping(GL_CLIP_PLANE0, left, -1);
glEnableClipping(GL_CLIP_PLANE1, right, 1);
glEnableClipping(GL_CLIP_PLANE2, top, -1);
glEnableClipping(GL_CLIP_PLANE3, bottom, 1);
}
/**
* Enable OpenGL clipping planes (uses planes 0, 1, 2 and 3)
*
* @param rect Clipping rectangle
*/
public static void glEnableClipping(Rectangle rect)
{
GLClippingPlanes.clippingPlaneFlags = 0;
glEnableClipping(GL_CLIP_PLANE0, rect.getX(), -1);
glEnableClipping(GL_CLIP_PLANE1, rect.getX() + rect.getWidth(), 1);
glEnableClipping(GL_CLIP_PLANE2, rect.getY(), -1);
glEnableClipping(GL_CLIP_PLANE3, rect.getY() + rect.getHeight(), 1);
}
/**
* Enable horizontal clipping planes (left and right) (uses planes 0, 1)
*
* @param left Left edge clip or -1 to not use this plane
* @param right Right edge clip or -1 to not use this plane
*/
public static void glEnableHorizontalClipping(int left, int right)
{
glEnableClipping(GL_CLIP_PLANE0, left, -1);
glEnableClipping(GL_CLIP_PLANE1, right, 1);
}
/**
* Enable vertical clipping planes (top and bottom) (uses planes 2, 3)
*
* @param top Top edge clip or -1 to not use this plane
* @param bottom Bottom edge clip or -1 to not use this plane
*/
public static void glEnableVerticalClipping(int top, int bottom)
{
glEnableClipping(GL_CLIP_PLANE2, top, -1);
glEnableClipping(GL_CLIP_PLANE3, bottom, 1);
}
/**
* @param plane
* @param value
*/
public static void glEnableClipping(int plane, int value)
{
if (plane < GL_CLIP_PLANE0 || plane >= (GL_CLIP_PLANE0 + GLClippingPlanes.totalClippingPlanes))
{
throw new IllegalArgumentException("Invalid clipping plane enum specified GL_CLIP_PLANE" + (plane - GL_CLIP_PLANE0));
}
glEnableClipping(plane, value, (plane % 2 == 0) ? -1 : 1);
}
/**
* @param plane
* @param value
*/
public static void glEnableClipping(Plane plane, int value)
{
glEnableClipping(plane.plane, value, plane.sign);
}
/**
* Enable clipping on a particular axis
*
* @param plane Clipping plane to enable
* @param value Clipping plane position
* @param sign Sign of the position
*/
private static void glEnableClipping(int plane, int value, int sign)
{
if (value == -1) return;
int offset = (plane - GL_CLIP_PLANE0) << 2;
GLClippingPlanes.doubleBuffer.put(offset + 3, value * sign).position(offset);
GLClippingPlanes.clippingPlaneFlags |= plane;
glClipPlane(plane, GLClippingPlanes.doubleBuffer);
glEnable(plane);
}
/**
* Enable clipping planes which were previously enabled
*/
public static void glEnableClipping()
{
if ((GLClippingPlanes.clippingPlaneFlags & GL_CLIP_PLANE0) == GL_CLIP_PLANE0) glEnable(GL_CLIP_PLANE0);
if ((GLClippingPlanes.clippingPlaneFlags & GL_CLIP_PLANE1) == GL_CLIP_PLANE1) glEnable(GL_CLIP_PLANE1);
if ((GLClippingPlanes.clippingPlaneFlags & GL_CLIP_PLANE2) == GL_CLIP_PLANE2) glEnable(GL_CLIP_PLANE2);
if ((GLClippingPlanes.clippingPlaneFlags & GL_CLIP_PLANE3) == GL_CLIP_PLANE3) glEnable(GL_CLIP_PLANE3);
}
/**
* Disable OpenGL clipping planes (uses planes 2, 3, 4 and 5)
*/
public static void glDisableClipping()
{
glDisable(GL_CLIP_PLANE3);
glDisable(GL_CLIP_PLANE2);
glDisable(GL_CLIP_PLANE1);
glDisable(GL_CLIP_PLANE0);
}
}