protected void beginDrawAnnotations(DrawContext dc, OGLStackHandler stackHandler)
{
GL2 gl = dc.getGL().getGL2(); // GL initialization checks for GL2 compatibility.
int attributeMask = GL2.GL_COLOR_BUFFER_BIT // for alpha test func and ref, blend func
| GL2.GL_CURRENT_BIT // for current color
| GL2.GL_DEPTH_BUFFER_BIT // for depth test, depth mask, depth func
| GL2.GL_ENABLE_BIT // for enable/disable changes
| GL2.GL_HINT_BIT // for line smoothing hint
| GL2.GL_LINE_BIT // for line width, line stipple
| GL2.GL_TRANSFORM_BIT // for matrix mode
| GL2.GL_VIEWPORT_BIT; // for viewport, depth range
stackHandler.pushAttrib(gl, attributeMask);
// Load a parallel projection with dimensions (viewportWidth, viewportHeight)
stackHandler.pushProjectionIdentity(gl);
gl.glOrtho(0d, dc.getView().getViewport().width, 0d, dc.getView().getViewport().height, -1d, 1d);
// Push identity matrices on the texture and modelview matrix stacks. Leave the matrix mode as modelview.
stackHandler.pushTextureIdentity(gl);
stackHandler.pushModelviewIdentity(gl);
// Enable the alpha test.
gl.glEnable(GL2.GL_ALPHA_TEST);
gl.glAlphaFunc(GL2.GL_GREATER, 0.0f);
// Apply the depth buffer but don't change it.
if ((!dc.isDeepPickingEnabled()))
{
gl.glEnable(GL.GL_DEPTH_TEST);
}
gl.glDepthMask(false);
// Disable lighting and backface culling.
gl.glDisable(GL2.GL_LIGHTING);
gl.glDisable(GL.GL_CULL_FACE);
if (!dc.isPickingMode())
{
// Enable blending in premultiplied color mode.
gl.glEnable(GL.GL_BLEND);
OGLUtil.applyBlending(gl, true);
}
else
{
this.pickSupport.beginPicking(dc);
}
}
/**
* Sets the GL blending state according to the specified color mode. If <code>havePremultipliedColors</code> is
* true, this applies a blending function appropriate for colors premultiplied by the alpha component. Otherwise,
* this applies a blending function appropriate for non-premultiplied colors.
*
* @param gl the GL context.
* @param havePremultipliedColors true to configure blending for colors premultiplied by the alpha components, and
* false to configure blending for non-premultiplied colors.
*
* @throws ArgumentException if the GL is null.
*/
public static void applyBlending(GL2 gl, bool havePremultipliedColors)
{
if (gl == null)
{
String message = Logging.getMessage("nullValue.GLIsNull");
Logging.logger().severe(message);
throw new ArgumentException(message);
}
gl.glEnable(GL2.GL_ALPHA_TEST);
gl.glAlphaFunc(GL2.GL_GREATER, 0.0f);
if (havePremultipliedColors)
{
gl.glBlendFunc(GL.GL_ONE, GL.GL_ONE_MINUS_SRC_ALPHA);
}
else
{
// The separate blend function correctly handles regular (non-premultiplied) colors. We want
// Cd = Cs*As + Cf*(1-As)
// Ad = As + Af*(1-As)
// So we use GL_EXT_blend_func_separate to specify different blending factors for source color and source
// alpha.
bool haveExtBlendFuncSeparate = gl.isExtensionAvailable(GL_EXT_BLEND_FUNC_SEPARATE);
if (haveExtBlendFuncSeparate)
{
gl.glBlendFuncSeparate(
GL.GL_SRC_ALPHA, GL.GL_ONE_MINUS_SRC_ALPHA, // rgb blending factors
GL.GL_ONE, GL.GL_ONE_MINUS_SRC_ALPHA); // alpha blending factors
}
else
{
gl.glBlendFunc(GL.GL_SRC_ALPHA, GL.GL_ONE_MINUS_SRC_ALPHA);
}
}
}
