GLShadowFrameBuffer.cpp

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////////////////////////////////////////////////////////////////////////////////
//    Scorched3D (c) 2000-2009
//
//    This file is part of Scorched3D.
//
//    Scorched3D is free software; you can redistribute it and/or modify
//    it under the terms of the GNU General Public License as published by
//    the Free Software Foundation; either version 2 of the License, or
//    (at your option) any later version.
//
//    Scorched3D is distributed in the hope that it will be useful,
//    but WITHOUT ANY WARRANTY; without even the implied warranty of
//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//    GNU General Public License for more details.
//
//    You should have received a copy of the GNU General Public License
//    along with Scorched3D; if not, write to the Free Software
//    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
////////////////////////////////////////////////////////////////////////////////

#include <GLEXT/GLShadowFrameBuffer.h>
#include <GLEXT/GLStateExtension.h>

GLShadowFrameBuffer::GLShadowFrameBuffer() : 
        frameBufferObject_(0), depthTextureObject_(0),
        width_(0), height_(0)
{
}

GLShadowFrameBuffer::~GLShadowFrameBuffer()
{
        destroy();
}

bool GLShadowFrameBuffer::create(int width, int height)
{
        width_ = width;
        height_ = height;

        // Create texture
        glGenTextures(1, &depthTextureObject_);
        glBindTexture(GL_TEXTURE_2D, depthTextureObject_);

        glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, width, height, 0, 
                GL_DEPTH_COMPONENT, GL_UNSIGNED_INT, 0);                

        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); 
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); 
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_MODE_ARB, GL_COMPARE_R_TO_TEXTURE_ARB);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_FUNC_ARB, GL_LEQUAL);
        glTexParameteri(GL_TEXTURE_2D, GL_DEPTH_TEXTURE_MODE_ARB, GL_INTENSITY); 

        // Create framebuffer
        glGenFramebuffersEXT(1, &frameBufferObject_);
        glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, frameBufferObject_);

        glReadBuffer(GL_NONE);
        glDrawBuffer(GL_NONE);

        glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, 
                GL_DEPTH_ATTACHMENT_EXT, GL_TEXTURE_2D, depthTextureObject_, 0);
        glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, 
                GL_DEPTH_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, depthTextureObject_);

        GLenum status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);  
        if (status != GL_FRAMEBUFFER_COMPLETE_EXT) 
        {
                return false;
        }
        glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);

        return true;
}

void GLShadowFrameBuffer::bindDepthTexture()
{
        glBindTexture(GL_TEXTURE_2D, depthTextureObject_);
        GLTexture::setLastBind(0);
}

void GLShadowFrameBuffer::destroy()
{
        if (!bufferValid()) return;

        //Activate the frame buffer objcet
        glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, frameBufferObject_);

        //Detach our depth texture from the frame buffer object
        glFramebufferTexture2DEXT(
                GL_FRAMEBUFFER_EXT,
                GL_DEPTH_ATTACHMENT_EXT,
                GL_TEXTURE_2D, 
                0,
                0);
        glFramebufferRenderbufferEXT(
                GL_FRAMEBUFFER_EXT, 
                GL_DEPTH_ATTACHMENT_EXT, 
                GL_RENDERBUFFER_EXT, 
                0);

        //DeActivate the frame buffer objcet
        glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);

        //Delete the frame buffer object
        glDeleteFramebuffersEXT(1, &frameBufferObject_);

        frameBufferObject_ = 0;

        // Delete texture
        glDeleteTextures(1, &depthTextureObject_);
        depthTextureObject_ = 0;
}

void GLShadowFrameBuffer::bind()
{
        glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, frameBufferObject_);
}

void GLShadowFrameBuffer::unBind()
{
        glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
}

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