Ogre's compositors are definitely useful and elegant due to their .compositor scripts as well as natural compliance with Ogre's viewports. However - say you have a shader effect that you simply want to render to a texture. Well, here's some quick utilities to do this:
string.hpp
#ifndef STRING_HPP_INCLUDED
#define STRING_HPP_INCLUDED
#include <OgreString.h>
namespace engine
{
typedef Ogre::String string;
}
#endif // STRING_HPP_INCLUDED
pre_ogre.hpp
#ifndef PRE_OGRE_HPP_INCLUDED #define PRE_OGRE_HPP_INCLUDED #include <OgrePrerequisites.h> #endif // PRE_OGRE_HPP_INCLUDED
sseffect.hpp
#ifndef SSEFFECT_HPP_INCLUDED
#define SSEFFECT_HPP_INCLUDED
#include <map>
#include <OgrePixelFormat.h>
#include <boost/shared_ptr.hpp>
#include "pre_ogre.hpp"
#include "string.hpp"
namespace engine
{
namespace gfx
{
class renderer;
class sseffect
{
protected:
Ogre::Camera *_camera;
Ogre::Viewport *_viewport;
Ogre::Texture *_texture;
bool _textureIsExtern;
Ogre::RenderTarget *_rt;
Ogre::Pass *_pass;
const renderer &_renderer;
bool _active;
public:
sseffect(const renderer &r);
virtual ~sseffect();
virtual void create(const engine::string &name,
size_t w = 256, size_t h = 256,
Ogre::PixelFormat pf = Ogre::PF_R8G8B8);
virtual void create(Ogre::Texture *tex);
virtual void destroy();
virtual void update() const;
virtual void clear() const;
Ogre::Camera *camera() const { return _camera; }
Ogre::Viewport *viewport() const { return _viewport; }
Ogre::Texture *texture() const { return _texture; }
Ogre::RenderTarget *rt() const { return _rt; }
Ogre::Pass *pass() const { return _pass; }
void pass(Ogre::Pass *p) { _pass = p; }
bool active() const { return _active; }
void active(bool b) { _active = b; }
};
typedef boost::shared_ptr<sseffect> sseffectPtr;
class sseffectManager
{
private:
typedef std::map<engine::string, sseffectPtr> effectList;
effectList _effects;
sseffectPtr _tempEffect;
public:
void clear()
{
_effects.clear();
}
sseffectManager &operator +=(const sseffectPtr &p)
{
_tempEffect = p; // hold on to pointer
return *this;
}
void operator ,(const engine::string &name)
{
if (_tempEffect)
{
_effects[name] = _tempEffect;
_tempEffect.reset();
}
}
sseffectPtr operator -=(const engine::string &name)
{
effectList::iterator i = _effects.find(name);
// if not found, then just do nothing
if (i == _effects.end())
return sseffectPtr();
// copy effect
sseffectPtr ptr = i->second;
// erase it
_effects.erase(i);
// return it
return ptr;
}
sseffectPtr operator [](const engine::string &name)
{
effectList::iterator i = _effects.find(name);
// if not found, then just do nothing
if (i == _effects.end())
return sseffectPtr();
// return it
return i->second;
}
void operator()() const
{
effectList::const_iterator i = _effects.begin();
for (; i != _effects.end(); ++i)
{
const sseffectPtr &p = i->second;
p->update();
}
}
};
}
}
#endif // SSEFFECT_HPP_INCLUDED
sseffect.cpp
#include <OgreViewport.h>
#include <OgreCamera.h>
#include <OgreRenderTarget.h>
#include <OgrePixelFormat.h>
#include <OgreTextureManager.h>
#include <OgrePass.h>
#include <OgreSceneManager.h>
#include <OgreTexture.h>
#include <OgreHardwarePixelBuffer.h>
#include <OgreRoot.h>
#include <OgreRenderTexture.h>
#include <OgreRenderSystem.h>
#include "sseffect.hpp"
#include "renderer.hpp"
namespace engine
{
namespace gfx
{
sseffect::sseffect(const renderer &r):
_camera(NULL),
_viewport(NULL),
_texture(NULL),
_textureIsExtern(false),
_rt(NULL),
_pass(NULL),
_renderer(r),
_active(true)
{
}
sseffect::~sseffect()
{
destroy();
}
void sseffect::destroy()
{
if (!_textureIsExtern)
{
if (_texture)
Ogre::TextureManager::getSingleton().remove(_texture->getName());
if (_camera)
_camera->getSceneManager()->destroyCamera(_camera);
_texture = NULL;
_camera = NULL;
_rt = NULL;
_viewport = NULL;
}
}
void sseffect::create(
const engine::string &name, size_t w, size_t h, Ogre::PixelFormat pf)
{
destroy();
Ogre::TexturePtr midPtr = Ogre::TextureManager::getSingleton().createManual(
name, "Internal", Ogre::TEX_TYPE_2D, w, h, 0, // 0 mip maps
pf, Ogre::TU_RENDERTARGET);
_texture = midPtr.get(); _textureIsExtern = false;
_rt = _texture->getBuffer(0)->getRenderTarget(0);
_rt->setAutoUpdated(false);
_camera = _renderer.sceneMgr()->createCamera(name + "_camera");
_viewport = _rt->addViewport(_camera, _rt->getNumViewports());
_viewport->setBackgroundColour(Ogre::ColourValue::White);
_viewport->setClearEveryFrame(false);
_viewport->setShadowsEnabled(false);
_camera->setAspectRatio(float(w) / h);
_camera->setFOVy(Ogre::Degree(90));
}
void sseffect::create(Ogre::Texture *tex)
{
destroy();
_texture = tex; _textureIsExtern = true;
_rt = _texture->getBuffer(0)->getRenderTarget(0);
_viewport = _rt->getViewport(0);
_camera = _viewport->getCamera();
}
void sseffect::update() const
{
if (!_active || !_pass) return;
_renderer.fsquad(_pass, _viewport);
}
void sseffect::clear() const
{
_renderer.renderSys()->_setViewport(_viewport);
_renderer.renderSys()->clearFrameBuffer(
Ogre::FBT_COLOUR | Ogre::FBT_DEPTH | Ogre::FBT_STENCIL,
_viewport->getBackgroundColour());
}
}
}
renderer.hpp
#ifndef RENDERER_HPP_INCLUDED
#define RENDERER_HPP_INCLUDED
#include "pre_ogre.hpp"
#include "string.hpp"
namespace engine
{
namespace gfx
{
class renderer
{
protected:
Ogre::SceneManager *_sceneMgr;
Ogre::Viewport *_viewport;
Ogre::Camera *_camera;
Ogre::ManualObject *_quad;
void destroyQuad();
void buildQuad(Ogre::Camera *cam);
public:
renderer(Ogre::SceneManager *sceneMgr, Ogre::Viewport *viewport);
virtual ~renderer();
void ensureQuad();
void fsquad(Ogre::Pass *p, Ogre::Viewport *vp) const;
Ogre::SceneManager *sceneMgr() const { return _sceneMgr; }
Ogre::Viewport *viewport() const { return _viewport; }
Ogre::Camera *camera() const { return _camera; }
Ogre::RenderSystem *renderSys() const;
};
}
}
#endif // RENDERER_HPP_INCLUDED
renderer.cpp
#include <OgreCamera.h>
#include <OgreRoot.h>
#include <OgreRenderSystem.h>
#include <OgreViewport.h>
#include <OgreSceneManager.h>
#include <OgreManualObject.h>
#include "renderer.hpp"
#include "string.hpp"
namespace engine
{
namespace gfx
{
Ogre::RenderSystem *renderer::renderSys() const
{
return Ogre::Root::getSingleton().getRenderSystem();
}
renderer::renderer(Ogre::SceneManager *sceneMgr, Ogre::Viewport *viewport):
_sceneMgr(sceneMgr),
_viewport(viewport),
_camera(viewport->getCamera()),
_quad(NULL)
{
ensureQuad();
}
renderer::~renderer()
{
destroyQuad();
}
void renderer::destroyQuad()
{
if (_quad)
_sceneMgr->destroyManualObject(_quad);
_quad = NULL;
}
void renderer::buildQuad(Ogre::Camera *cam)
{
destroyQuad();
_quad = _sceneMgr->createManualObject("renderer::_quad");
//! (courtesy of Ogre API docs)
//! The corners are ordered as follows:
//! [0] = top-right near
//! [1] = top-left near
//! [2] = bottom-left near
//! [3] = bottom-right near
//! [4] = top-right far <--- want
//! [5] = top-left far <--- want
//! [6] = bottom-left far <--- want
//! [7] = bottom-right far <--- want
const vec3 *CORNERS = cam->getWorldSpaceCorners();
//! we want them in VIEW-SPACE!!! very important!
mat4 viewMat = cam->getViewMatrix(true);
_quad->clear();
_quad->begin("BaseWhiteNoLighting", Ogre::RenderOperation::OT_TRIANGLE_LIST);
{
//! store frustum corner in normal attribute
//! go anti-clockwise
// top-left
_quad->position(Ogre::Vector3(-1, 1, 0));
_quad->normal(viewMat * CORNERS[5]);
_quad->textureCoord(Ogre::Vector2(0, 0));
// bottom-left
_quad->position(Ogre::Vector3(-1, -1, 0));
_quad->normal(viewMat * CORNERS[6]);
_quad->textureCoord(Ogre::Vector2(0, 1));
// bottom-right
_quad->position(Ogre::Vector3(1, -1, 0));
_quad->normal(viewMat * CORNERS[7]);
_quad->textureCoord(Ogre::Vector2(1, 1));
// top-right
_quad->position(Ogre::Vector3(1, 1, 0));
_quad->normal(viewMat * CORNERS[4]);
_quad->textureCoord(Ogre::Vector2(1, 0));
// we put the vertices in anti-clockwise,
// so just start at 0 and go to 3
_quad->quad(0, 1, 2, 3);
}
_quad->end();
}
void renderer::ensureQuad()
{
buildQuad(_camera);
}
void renderer::fsquad(Ogre::Pass *p, Ogre::Viewport *vp) const
{
if (!_quad)
{
return;
}
Ogre::RenderSystem *renderSys = Ogre::Root::getSingleton().getRenderSystem();
Ogre::RenderOperation rop;
_quad->getSection(0)->getRenderOperation(rop);
renderSys->_setViewport(vp); // render to said viewport
_sceneMgr->_setPass(p, true, false); // parse the pass
// bind/unbind GPU programs
if (p->hasVertexProgram())
renderSys->bindGpuProgramParameters(
Ogre::GPT_VERTEX_PROGRAM, p->getVertexProgramParameters());
else
renderSys->unbindGpuProgram(Ogre::GPT_VERTEX_PROGRAM);
if (p->hasFragmentProgram())
renderSys->bindGpuProgramParameters(
Ogre::GPT_FRAGMENT_PROGRAM, p->getFragmentProgramParameters());
else
renderSys->unbindGpuProgram(Ogre::GPT_FRAGMENT_PROGRAM);
// clear any matrices
renderSys->_setWorldMatrix(mat4::IDENTITY);
renderSys->_setViewMatrix(mat4::IDENTITY);
renderSys->_setProjectionMatrix(mat4::IDENTITY);
renderSys->_beginFrame();
{
renderSys->_render(rop);
}
renderSys->_endFrame();
}
}
}
Also, here is some relevant shading:
fsquad.material
vertex_program fsquad_vs cg
{
source utils.cg
entry_point fsquad_vs
profiles vs_1_1 arbvp1
}
fsquad.cg
struct FragIn_fsquad
{
float2 uv : TEXCOORD0;
float3 ray: TEXCOORD1;
};
struct VertOut_fsquad
{
float4 p : POSITION;
float2 uv : TEXCOORD0;
float3 ray: TEXCOORD1;
};
VertOut_fsquad fsquad_vs(in float4 p : POSITION, in float3 n : NORMAL, in float2 uv : TEXCOORD0)
{
VertOut_fsquad OUT;
OUT.p = p;
OUT.uv = uv;
OUT.ray = n;
return OUT;
}
The renderer has more to it than just the quadrilateral rendering, but in this case this is all that it is used for.
Example usage for the SSAO demo:
#include <OgreMaterialManager.h>
#include <OgreMaterial.h>
#include <OgrePass.h>
#include <OgreTechnique.h>
#include <OgreCamera.h>
#include "string.hpp"
#include "renderer.hpp"
#include "sseffect.hpp"
namespace engine
{
namespace gfx
{
class ssao: public sseffect
{
private:
void create(Ogre::Texture *et) {}
public:
ssao(const renderer &r);
virtual ~ssao();
void update() const;
};
ssao::ssao(const renderer &r):
sseffect(r)
{
if (!Ogre::MaterialManager::getSingleton().resourceExists("compute_ssao"))
{
return;
}
Ogre::MaterialPtr mat = (Ogre::MaterialPtr)
Ogre::MaterialManager::getSingleton().load("compute_ssao", "Internal");
_pass = mat->getTechnique(0)->getPass(0);
}
ssao::~ssao()
{
}
void ssao::update() const
{
clear();
if (!_active || !_pass || !_pass->hasFragmentProgram())
return;
Ogre::GpuProgramParametersSharedPtr params =
_pass->getFragmentProgramParameters();
if (params->_findNamedConstantDefinition("pMat"))
params->setNamedConstant(
"pMat",
CLIP_SPACE_TO_IMAGE_SPACE * // automatic scale/bias
_renderer.camera()->getProjectionMatrixWithRSDepth());
if (params->_findNamedConstantDefinition("texSize"))
{
vec4 texSize(1.0 / _texture->getWidth(), 1.0 / _texture->getHeight(), 0, 0);
params->setNamedConstant("texSize", texSize);
}
if (params->_findNamedConstantDefinition("far"))
params->setNamedConstant("far", _renderer.camera()->getFarClipDistance());
sseffect::update();
}
}
}
engine::gfx::renderer renderer(sceneManager, viewport);
engine::gfx::sseffectManager effects;
engine::gfx::sseffectPtr _ssao(new engine::gfx::ssao(renderer));
_ssao->create("ssao_texture", width, height, Ogre::PF_R8G8B8);
effects += _ssao, "ssao";
main loop
{
// do stuff
// update effects
effects();
// render scene
}
I pretty much pulled this code straight out of Portalized, so it's in the engine::gfx namespace. Feel free to take it out and what-not. Also feel free to modify the code to your own needs. This is not production code and it is not guaranteed to be fast, bug-free, and it is not guaranteed to work at all (though it probably will...).
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