From 6cead503317fa6e771b371bfb4dd381472b60113 Mon Sep 17 00:00:00 2001
From: Kenneth Russel <kbrussel@alum.mit.edu>
Date: Tue, 4 Sep 2007 02:35:52 +0000
Subject: Added support for loading non-mipmapped, non-power-of-two compressed
 textures on pre-OpenGL 2.0 hardware by first loading an "empty" compressed
 texture and then updating a sub-rectangle of its image. Straightforward port
 of this code to the mipmapped case did not work; added error checking for
 this case and throwing of GLException. Bug pointed out by Dave Collins from
 NASA World Wind Java project.

git-svn-id: file:///usr/local/projects/SUN/JOGL/git-svn/svn-server-sync/jogl/trunk@1354 232f8b59-042b-4e1e-8c03-345bb8c30851
---
 .../com/sun/opengl/util/texture/spi/DDSImage.java  | 36 ++++++++++++++++++++++
 1 file changed, 36 insertions(+)

(limited to 'src/classes/com/sun/opengl/util/texture/spi/DDSImage.java')

diff --git a/src/classes/com/sun/opengl/util/texture/spi/DDSImage.java b/src/classes/com/sun/opengl/util/texture/spi/DDSImage.java
index 52dbc25b1..835025b5c 100755
--- a/src/classes/com/sun/opengl/util/texture/spi/DDSImage.java
+++ b/src/classes/com/sun/opengl/util/texture/spi/DDSImage.java
@@ -43,6 +43,9 @@ import java.io.*;
 import java.nio.*;
 import java.nio.channels.*;
 
+import javax.media.opengl.*;
+import com.sun.opengl.util.*;
+
 /** A reader and writer for DirectDraw Surface (.dds) files, which are
     used to describe textures. These files can contain multiple mipmap
     levels in one file. This class is currently minimal and does not
@@ -469,6 +472,39 @@ public class DDSImage {
     return buf.toString();
   }
 
+  /** Allocates a temporary, empty ByteBuffer suitable for use in a
+      call to glCompressedTexImage2D. This is used by the Texture
+      class to expand non-power-of-two DDS compressed textures to
+      power-of-two sizes on hardware not supporting OpenGL 2.0 and the
+      NPOT texture extension. The specified OpenGL internal format
+      must be one of GL_COMPRESSED_RGB_S3TC_DXT1_EXT,
+      GL_COMPRESSED_RGBA_S3TC_DXT1_EXT,
+      GL_COMPRESSED_RGBA_S3TC_DXT3_EXT, or
+      GL_COMPRESSED_RGBA_S3TC_DXT5_EXT.
+  */
+  public static ByteBuffer allocateBlankBuffer(int width,
+                                               int height,
+                                               int openGLInternalFormat) {
+    int size = width * height;
+    switch (openGLInternalFormat) {
+      case GL.GL_COMPRESSED_RGB_S3TC_DXT1_EXT:
+      case GL.GL_COMPRESSED_RGBA_S3TC_DXT1_EXT:
+        size /= 2;
+        break;
+
+      case GL.GL_COMPRESSED_RGBA_S3TC_DXT3_EXT:
+      case GL.GL_COMPRESSED_RGBA_S3TC_DXT5_EXT:
+        break;
+
+      default:
+        throw new IllegalArgumentException("Illegal OpenGL texture internal format " +
+                                           openGLInternalFormat);
+    }
+    if (size == 0)
+      size = 1;
+    return BufferUtil.newByteBuffer(size);
+  }
+
   public void debugPrint() {
     PrintStream tty = System.err;
     tty.println("Compressed texture: " + isCompressed());
-- 
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