BansheeEngine/BansheeGLRenderSystem/Source/BsGLRenderTexture.cpp

#include "BsGLRenderTexture.h"
#include "BsGLPixelFormat.h"
#include "BsGLPixelBuffer.h"
#include "BsTextureView.h"

namespace BansheeEngine 
{
#define PROBE_SIZE 16

	static const GLenum depthFormats[] =
	{
		GL_NONE,
		GL_DEPTH_COMPONENT16,
		GL_DEPTH_COMPONENT32,
		GL_DEPTH24_STENCIL8,
		GL_DEPTH32F_STENCIL8
	};

	static const UINT32 depthBits[] =
	{
		0, 16, 32, 24, 32
	};

#define DEPTHFORMAT_COUNT (sizeof(depthFormats)/sizeof(GLenum))

	GLRenderTextureCore::GLRenderTextureCore(GLRenderTexture* parent, RenderTextureProperties* properties, const RENDER_SURFACE_DESC& colorSurfaceDesc,
		const RENDER_SURFACE_DESC& depthStencilSurfaceDesc)
		:RenderTextureCore(parent, properties, colorSurfaceDesc, depthStencilSurfaceDesc), mFB(nullptr)
	{
		if (mFB != nullptr)
			bs_delete<PoolAlloc>(mFB);

		mFB = bs_new<GLFrameBufferObject, PoolAlloc>();

		GLSurfaceDesc surfaceDesc;
		surfaceDesc.numSamples = properties->getMultisampleCount();
		surfaceDesc.zoffset = 0;

		GLTexture* glTexture = static_cast<GLTexture*>(mColorSurface->getTexture().get());
		surfaceDesc.buffer = glTexture->getBuffer(mColorSurface->getFirstArraySlice(), mColorSurface->getMostDetailedMip());

		mFB->bindSurface(0, surfaceDesc);

		GLTexture* glDepthStencilTexture = static_cast<GLTexture*>(mDepthStencilSurface->getTexture().get());
		GLPixelBufferPtr depthStencilBuffer =
			glDepthStencilTexture->getBuffer(mDepthStencilSurface->getFirstArraySlice(), mDepthStencilSurface->getMostDetailedMip());

		mFB->bindDepthStencil(depthStencilBuffer);
	}

	GLRenderTextureCore::~GLRenderTextureCore()
	{
		if (mFB != nullptr)
			bs_delete<PoolAlloc>(mFB);
	}

	void GLRenderTextureCore::getCustomAttribute(const String& name, void* pData) const
	{
		if(name=="FBO")
		{
			*static_cast<GLFrameBufferObject **>(pData) = mFB;
		}
		else if (name == "GL_FBOID" || name == "GL_MULTISAMPLEFBOID")
		{
			*static_cast<GLuint*>(pData) = mFB->getGLFBOID();
		}
	}

	RenderTargetProperties* GLRenderTexture::createProperties() const
	{
		return bs_new<RenderTextureProperties>();
	}

	RenderTextureCore* GLRenderTexture::createCore(RenderTextureProperties* properties, const RENDER_SURFACE_DESC& colorSurfaceDesc,
		const RENDER_SURFACE_DESC& depthStencilSurfaceDesc)
	{
		return bs_new<GLRenderTextureCore>(this, properties, colorSurfaceDesc, depthStencilSurfaceDesc);
	}

	GLRTTManager::GLRTTManager()
		:mBlitReadFBO(0), mBlitWriteFBO(0)
    {
		detectFBOFormats();
		
		glGenFramebuffersEXT(1, &mBlitReadFBO);
		glGenFramebuffersEXT(1, &mBlitWriteFBO);
    }

	GLRTTManager::~GLRTTManager()
	{
		glDeleteFramebuffersEXT(1, &mBlitReadFBO);
		glDeleteFramebuffersEXT(1, &mBlitWriteFBO);
	}

	bool GLRTTManager::_tryFormat(GLenum depthFormat, GLenum stencilFormat)
    {
        GLuint status, depthRB = 0, stencilRB = 0;
        bool failed = false;

        if(depthFormat != GL_NONE)
        {
            // Generate depth renderbuffer
            glGenRenderbuffersEXT(1, &depthRB);

            // Bind it to FBO
            glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, depthRB);
            
            // Allocate storage for depth buffer
            glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, depthFormat,
                                PROBE_SIZE, PROBE_SIZE);
            
            // Attach depth
            glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT,
                                    GL_RENDERBUFFER_EXT, depthRB);
        }

        if(stencilFormat != GL_NONE)
        {
            // Generate stencil renderbuffer
            glGenRenderbuffersEXT(1, &stencilRB);

            // Bind it to FBO
            glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, stencilRB);
            glGetError(); 

            // Allocate storage for stencil buffer
            glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, stencilFormat,
                                PROBE_SIZE, PROBE_SIZE); 

            if(glGetError() != GL_NO_ERROR)
                failed = true;

            // Attach stencil
            glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_STENCIL_ATTACHMENT_EXT,
                            GL_RENDERBUFFER_EXT, stencilRB);

            if(glGetError() != GL_NO_ERROR)
                failed = true;
        }
        
        status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);

        // Detach and destroy
        glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, 0);
        glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_STENCIL_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, 0);

        if (depthRB)
            glDeleteRenderbuffersEXT(1, &depthRB);

        if (stencilRB)
            glDeleteRenderbuffersEXT(1, &stencilRB);
        
        return status == GL_FRAMEBUFFER_COMPLETE_EXT && !failed;
    }
    
    bool GLRTTManager::_tryPackedFormat(GLenum packedFormat)
    {
        GLuint packedRB = 0;
        bool failed = false; // flag on GL errors

        // Generate renderbuffer
        glGenRenderbuffersEXT(1, &packedRB);

        // Bind it to FBO
        glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, packedRB);

        // Allocate storage for buffer
        glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, packedFormat, PROBE_SIZE, PROBE_SIZE);
        glGetError();

        // Attach depth
        glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT,
            GL_RENDERBUFFER_EXT, packedRB);

        if(glGetError() != GL_NO_ERROR)
            failed = true;

        // Attach stencil
        glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_STENCIL_ATTACHMENT_EXT,
            GL_RENDERBUFFER_EXT, packedRB);

        if(glGetError() != GL_NO_ERROR)
            failed = true;

        GLuint status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);

        // Detach and destroy
        glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, 0);
        glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_STENCIL_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, 0);
        glDeleteRenderbuffersEXT(1, &packedRB);

        return status == GL_FRAMEBUFFER_COMPLETE_EXT && !failed;
    }

    void GLRTTManager::detectFBOFormats()
    {
        // Try all formats, and report which ones work as target
        GLuint fb = 0, tid = 0;
        GLint old_drawbuffer = 0, old_readbuffer = 0;
        GLenum target = GL_TEXTURE_2D;

        glGetIntegerv (GL_DRAW_BUFFER, &old_drawbuffer);
        glGetIntegerv (GL_READ_BUFFER, &old_readbuffer);

        for(size_t x=0; x<PF_COUNT; ++x)
        {
            mProps[x].valid = false;

			// Fetch GL format token
			GLenum fmt = GLPixelUtil::getGLInternalFormat((PixelFormat)x);
            if(fmt == GL_NONE && x!=0)
                continue;

			// No test for compressed formats
			if(PixelUtil::isCompressed((PixelFormat)x))
				continue;

            // Create and attach framebuffer
            glGenFramebuffersEXT(1, &fb);
            glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fb);
            if (fmt!=GL_NONE && !PixelUtil::isDepth((PixelFormat)x))
            {
				// Create and attach texture
				glGenTextures(1, &tid);
				glBindTexture(target, tid);
				
                // Set some default parameters so it won't fail on NVidia cards         
				if (GLEW_VERSION_1_2)
					glTexParameteri(target, GL_TEXTURE_MAX_LEVEL, 0);
                glTexParameteri(target, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
                glTexParameteri(target, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
                glTexParameteri(target, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
                glTexParameteri(target, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
                            
				glTexImage2D(target, 0, fmt, PROBE_SIZE, PROBE_SIZE, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
				glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT,
                                target, tid, 0);
            }
			else
			{
				// Draw to nowhere -- stencil/depth only
				glDrawBuffer(GL_NONE);
				glReadBuffer(GL_NONE);
			}

            // Check status
            GLuint status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);

			// Ignore status in case of fmt==GL_NONE, because no implementation will accept
			// a buffer without *any* attachment. Buffers with only stencil and depth attachment
			// might still be supported, so we must continue probing.
            if(fmt == GL_NONE || status == GL_FRAMEBUFFER_COMPLETE_EXT)
            {
                mProps[x].valid = true;

                // For each depth/stencil formats
                for (UINT32 depth = 0; depth < DEPTHFORMAT_COUNT; ++depth)
                {
                    if (depthFormats[depth] != GL_DEPTH24_STENCIL8_EXT && depthFormats[depth] != GL_DEPTH32F_STENCIL8)
                    {
                        if (_tryFormat(depthFormats[depth], GL_NONE))
                        {
                            /// Add mode to allowed modes
                            FormatProperties::Mode mode;
                            mode.depth = depth;
                            mode.stencil = 0;
                            mProps[x].modes.push_back(mode);
                        }
                    }
                    else
                    {
                        // Packed depth/stencil format
                        if (_tryPackedFormat(depthFormats[depth]))
                        {
                            /// Add mode to allowed modes
                            FormatProperties::Mode mode;
                            mode.depth = depth;
                            mode.stencil = 0;   // unuse
                            mProps[x].modes.push_back(mode);
                        }
                    }
                }
            }

            // Delete texture and framebuffer
            glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
            glDeleteFramebuffersEXT(1, &fb);
			
			glFinish();
			
            if (fmt!=GL_NONE)
                glDeleteTextures(1, &tid);
        }

        // It seems a bug in nVidia driver: glBindFramebufferEXT should restore
        // draw and read buffers, but in some unclear circumstances it won't.
        glDrawBuffer(old_drawbuffer);
        glReadBuffer(old_readbuffer);

		String fmtstring = "";
        for(size_t x=0; x<PF_COUNT; ++x)
        {
            if(mProps[x].valid)
                fmtstring += PixelUtil::getFormatName((PixelFormat)x)+" ";
        }
    }
    
    PixelFormat GLRTTManager::getSupportedAlternative(PixelFormat format)
    {
        if(checkFormat(format))
            return format;

        // Find first alternative
        PixelComponentType pct = PixelUtil::getElementType(format);
        switch(pct)
        {
        case PCT_BYTE: format = PF_A8R8G8B8; break;
        case PCT_FLOAT16: format = PF_FLOAT16_RGBA; break;
        case PCT_FLOAT32: format = PF_FLOAT32_RGBA; break;
        case PCT_COUNT: break;
        }

        if(checkFormat(format))
            return format;

        // If none at all, return to default
        return PF_A8R8G8B8;
    }
}