Raymarching sur le GPU

Version imprimable

Bonsoir à tous,

Après avoir découvert la magie du Raymarching avec un article de Iñigo Quilez (http://www.iquilezles.org/www/articl...marchingdf.htm), et lu un code exemple (http://www.openprocessing.org/sketch/25016), j'ai voulu implémenter cette technique.

J'ai donc commencé par une version CPU qui fonctionne correctement:

Code:

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#include <SFML/Graphics.hpp>
#include <kT/Math/Vector3.hpp>
#include <kT/Math/Vector4.hpp>
#include <kT/Math/Helpers.hpp>
 
#include <sstream>
#include <string>
 
static unsigned width = 1680;
static unsigned height = 1050;
 
static float g_fTime = 0.f;
static float g_fStepMultiplier = 0.9f;
static unsigned g_MaxSteps = 100;
static float g_fMinDist = 0.001f;
static float g_fGradientEpsilon = 0.25f;
static unsigned g_iResolution = 4;// tile size
static int g_iNumRenderThreads = 1;
static kT::Vector3f32 g_vecLightDir1;
static kT::Vector3f32 g_vecLightDir2;
 
static kT::Vector3f32 s_vecCamPos;
static kT::Vector3f32 s_vecCamTo;
static float s_fFov;
static unsigned s_iStride;
static kT::Vector3f32 s_vecFwd;
static kT::Vector3f32 s_vecRight;
static kT::Vector3f32 s_vecUp;
 
 
float rmSphere( const kT::Vector3f32& f, float fRadius)
{
    return f.Length() - fRadius;
}
 
float rmRoundedCube(float fX, float fY, float fZ, float fSize, float fRadius)
{
	float fDX = kT::Max(abs(fX) - fSize + fRadius, 0.f);
	float fDY = kT::Max(abs(fY) - fSize + fRadius, 0.f);
	float fDZ = kT::Max(abs(fZ) - fSize + fRadius, 0.f);
	return sqrtf(fDX * fDX + fDY * fDY + fDZ * fDZ) - fRadius;
}
 
 
float getDistance(const kT::Vector3f32& vecPos)
{
    float fSphereDist1 = rmSphere(vecPos - kT::Vector3f32( 5.f, 0.f, 0.f ), 4.f);
	float fSphereDist2 = rmSphere(vecPos + kT::Vector3f32( 5.f, 0.f, 0.f ), 4.f);
	float fSphereDist3 = rmSphere(vecPos - kT::Vector3f32( 0.f, 5.f, 0.f ), 4.f);
	float fSphereDist4 = rmSphere(vecPos + kT::Vector3f32( 0.f, 5.f, 0.f ), 4.f);
	float fSphereDist5 = rmSphere(vecPos - kT::Vector3f32( 0.f, 0.f, 5.f ), 4.f);
	float fSphereDist6 = rmSphere(vecPos + kT::Vector3f32( 0.f, 0.f, 5.f ), 4.f);
	float fMinSphereDist = kT::Min( kT::Min( kT::Min( fSphereDist1, fSphereDist2 ), fSphereDist3 ), kT::Min( kT::Min( fSphereDist4, fSphereDist5 ), fSphereDist6 ));
	float fCubeDist = rmRoundedCube(vecPos.x, vecPos.y, vecPos.z, 6, 2);
	return kT::Max(fCubeDist, -fMinSphereDist);
}
 
kT::Vector3f32 gradient(float fX, float fY, float fZ)
{
	return kT::Vector3f32(
	getDistance(kT::Vector3f32(fX + g_fGradientEpsilon, fY, fZ)) -getDistance(kT::Vector3f32(fX - g_fGradientEpsilon, fY, fZ)),
	getDistance(kT::Vector3f32(fX, fY + g_fGradientEpsilon, fZ)) - getDistance(kT::Vector3f32(fX, fY - g_fGradientEpsilon, fZ)),
	getDistance(kT::Vector3f32(fX, fY, fZ + g_fGradientEpsilon)) - getDistance(kT::Vector3f32(fX, fY, fZ - g_fGradientEpsilon))
	);
}
 
struct RayMarchResult
{
	RayMarchResult(float fDist, float fComplexity):
     m_fDist(fDist),
	 m_fComplexity(fComplexity)
	{}
	float m_fDist;
	float m_fComplexity;
};
 
RayMarchResult rayMarch(const kT::Vector3f32& vecPos, const kT::Vector3f32& vecDir)
{
	kT::Vector3f32 vecCurrentPos = vecPos;
 
	float fDist = g_fMinDist;
	unsigned Step;
	for (Step = 1; Step < g_MaxSteps && fDist >= g_fMinDist; Step++)
	{
		fDist = getDistance(vecCurrentPos);
 
		// This is a bit of a hack that just so happens to work well with the current scenes by
		// stopping the rays from marching too far
		// Hacky.. but it gives a massive speed boost
		if(fDist > 100.f)
			return RayMarchResult(0.f, 0.f);
 
        kT::Vector3f32 vecStep = vecDir;
		vecStep *= (fDist * g_fStepMultiplier);
		vecCurrentPos += vecStep;
	}
 
	if (fDist < g_fMinDist)
		return RayMarchResult((vecPos-vecCurrentPos).Length(), 1.f/((float)Step));
	else
		return RayMarchResult(0, 0);
}
 
kT::Uint32 shade(const kT::Vector3f32& vecContactPos, const kT::Vector3f32& vecCamRay, const RayMarchResult& rayMarchResult)
{
	kT::Vector3f32 vecNorm = gradient(vecContactPos.x, vecContactPos.y, vecContactPos.z);
	float fR = 0, fG = 0, fB = 0;
	float fDiffTerm = kT::Clamp(vecNorm.Dot(g_vecLightDir1), 0.0f, 1.0f);
	fR += fDiffTerm * 1.5f; fG += fDiffTerm * 1.5f; fB += fDiffTerm * 1.5f;
	fR += 0.0f; fG += 0.0f; fB += 0.03f;  // Ambient
 
    kT::Uint32 r = kT::Min(fR * 255.f, 255.f);
    kT::Uint32 g = kT::Min(fG * 255.f , 255.f);
    kT::Uint32 b = kT::Min(fB * 255.f, 255.f);
 
    kT::Uint32 out = r | (g << 8) | (b << 16) | 0xff000000;
    return out;
}
 
 
class RenderThread
{
public:
  RenderThread(unsigned iStartY, unsigned iRenderHeight):
	m_iStartY(iStartY),
    m_iRenderHeight(iRenderHeight),
    m_iPixel( iStartY * width )
  {}
 
  unsigned m_iStartY;
  unsigned m_iRenderHeight;
  unsigned m_iPixel;
 
  void run( kT::Uint32* pixels )
  {
    for (unsigned y = m_iStartY; y < height - g_iResolution + 1; y += g_iResolution)
    {
      for (unsigned x = 0; x < width - g_iResolution + 1; x += g_iResolution)
      {
        kT::Vector3f32 vecCamRight = s_vecRight; vecCamRight *= (((float)x / (float)(width) - 0.5f) * s_fFov);
        kT::Vector3f32 vecCamUp = s_vecUp; vecCamUp *= (((float)y / (float)(height) - 0.5f) * s_fFov);
        kT::Vector3f32 vecCamDir = vecCamRight; vecCamDir+=vecCamUp; vecCamDir+=(s_vecFwd); vecCamDir.Normalize();
 
        RayMarchResult rayMarchResult = rayMarch(s_vecCamPos, vecCamDir);
        float fDistance = rayMarchResult.m_fDist;
        kT::Uint32 c;
        if (fDistance > 0.f)
        {
          // Ray hit our field - calculate the colour
          kT::Vector3f32 vecContactPos = vecCamDir; vecContactPos*=(fDistance); vecContactPos+=(s_vecCamPos);
          c = shade(vecContactPos, vecCamDir, rayMarchResult);
        }
        else
        {
          // Ray didn't hit anything - get background colour
          c = 122 + (0 * 255) + (255 * 65536) + 4278190080;
        }
 
        if (g_iResolution == 1)
          pixels[m_iPixel++] = c;
        else
        {
		  for (unsigned i = 0; i < g_iResolution; i++)
          {
			for (unsigned j = 0; j < g_iResolution; j++)
            {
              pixels[m_iPixel + width * j ] = c;
            }
            m_iPixel++;
          }
        }
      }
 
      m_iPixel += s_iStride;
    }
  }
};
 
void render( kT::Uint32* pixels )
{
	// Position camera
	s_vecCamPos = kT::Vector3f32(25.f * sin(g_fTime * 0.001f),
							21.f * sin(g_fTime * 0.0002f),
							25.f * cos(g_fTime * 0.001f));
	s_vecCamTo = kT::Vector3f32(0.f,
							0.f,
							0.f);
 
	// Figure out view vectors from camera position
	s_vecFwd = s_vecCamTo; s_vecFwd-=(s_vecCamPos); s_vecFwd.Normalize();
	s_vecUp = kT::Vector3f32(0.f, 1.f, 0.f);
	s_vecRight = s_vecFwd.Cross(s_vecUp);
	s_vecUp = s_vecRight.Cross(s_vecFwd);
	s_fFov = 1.0f;
 
	// Set up lights
	g_vecLightDir1 = kT::Vector3f32(-0.5f, -1.f, 0.f); g_vecLightDir1.Normalize();
	g_vecLightDir2 = kT::Vector3f32(0.5f, -1.f, 0.f); g_vecLightDir2.Normalize();
 
	// Create the render threads and start them running
	s_iStride = width * (g_iResolution - 1);
	int iRenderHeight = height / g_iNumRenderThreads;
	int iHeightRendered = height;
 
	RenderThread r(0, height);
	r.run( pixels );
}
 
template< typename T >
std::string toString( T i )
{
// créer un flux de sortie
    std::ostringstream oss;
    // écrire un nombre dans le flux
    oss << i;
    // récupérer une chaîne de caractères
    return oss.str();
}
 
int main()
{
	sf::RenderWindow window(sf::VideoMode(width, height), "ray Marching");
	width = window.getSize().x;
	height = window.getSize().y;
 
    kT::Uint32* pixels = new kT::Uint32[ width * height ];
 
	sf::Texture backbuff;
	backbuff.create( window.getSize().x, window.getSize().y );
 
	sf::Sprite screen(backbuff);
 
	sf::Font font;
	font.loadFromFile( "font.ttf" );
	sf::Text renderTimeText("render time inknown", font);
 
	sf::Clock clock;
 
	while( window.isOpen() )
	{
		sf::Event ev;
		while( window.pollEvent( ev ) )
		{
			if( ev.type == sf::Event::Closed )
				window.close();
		}
 
		sf::Time elapsedTime = clock.getElapsedTime();
		g_fTime = elapsedTime.asSeconds() * 1000.f;
 
		render( pixels );
        backbuff.update( reinterpret_cast<kT::Uint8*>(pixels) );
		window.draw( screen );
 
		float renderTime = clock.getElapsedTime().asSeconds() * 1000.f - g_fTime;
		renderTimeText.setString("Render time: " + toString(renderTime) + "ms");
		window.draw( renderTimeText );
 
		window.display();
	}
 
    delete[] pixels;
	return 0;
}

Et j'ai voulu ensuite passer à une impplémentation sur le gpu avec D3D11, pour avoir rendu bien accéléré.
Sauf que là - patatra - plus rien ne marche bien sûr!
En rapide: je rends un rectangle pour couvrir l'écran. Dans le pixel shader je suis sensé faire les calculs de RenderThread::run() de la version CPU.

Le code tient en trois fichiers:
Le main.cpp (je le mets au cas où l'erreur vienne de là, bien que je pense que ça vient plutôt du pixel shader).

Code:

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#include <kT/Core.hpp>
#include <kT/Math.hpp>
#include <kT/Window.hpp>
 
#include <kT/Graphics/D3D11Device/D3D11Device.hpp>
#include <kT/Graphics/D3D11Device/D3D11Shader.hpp>
#include <kT/Graphics/D3D11Device/D3D11SwapChain.hpp>
#include <kT/Graphics/D3D11Device/D3D11RasterizerState.hpp>
#include <kT/Graphics/D3D11Device/D3D11ImmediateContext.hpp>
#include <kT/Graphics/D3D11Device/D3D11DeviceTypes.hpp>
#include <kT/Graphics/D3D11Device/D3D11SamplerState.hpp>
#include <kT/Graphics/D3D11Device/D3D11Texture.hpp>
#include <kT/Graphics/D3D11Device/D3D11DepthStencilBuffer.hpp>
 
#include <D3D11.h>
 
int main( int argc, char** argv )
{
    kT::FileLogger* logger = new kT::FileLogger;
 
    kT::VideoMode mode = kT::VideoMode::GetDesktopMode();
#ifdef NDEBUG
	kT::Window* window = new kT::Window("Ray", kT::Sizeui32(800, 800), kT::Window::Overlapped );
#else
    kT::Window* window = new kT::Window("Ray", kT::Sizeui32(800, 800), kT::Window::Overlapped );
#endif
    window->Show();
 
    kT::D3D11Device* device;
	kT::D3D11ImmediateContext* immediateContext = 0;
    ID3D11Device* d3dDevice = 0;
    ID3D11DeviceContext* d3dImmediateContext = 0;
 
    try{
#ifndef NDEBUG
		try{
			device = new kT::D3D11Device(kT::D3D11Device< kTD3D11DeviceTemplateListLineTypes >::HardwareProcessing, true);
		} catch( kT::Exception& e )
		{
			device = new kT::D3D11Device();
		}
 
#else
		device = new kT::D3D11Device();
#endif
		immediateContext = device->GetImmediateContext();
        d3dDevice = device->GetHandle();
		d3dImmediateContext = immediateContext->GetHandle();;
        if( device->GetFeatureLevel() == D3D_FEATURE_LEVEL_11_0 )
            logger->Log( kT::Logger::InfoMessage, "Feature level 11!" );
    } catch( kT::Exception& e )
    {
        logger->Log( kT::Logger::CriticalErrorMessage, "Can't create the device");
        return -1;
    }
 
    kT::D3D11SwapChain* pSwapChain;
    try{
        pSwapChain = new kT::D3D11SwapChain( d3dDevice, window, kT::PixelFormat::RGBA8_UNORM, window->GetSize(), true, 1 );
    } catch( kT::Exception& e )
    {
        logger->Log( kT::Logger::CriticalErrorMessage, "Can't create the swapchain" );
        return -1;
    }
 
	ID3D11RenderTargetView* renderTargetView = pSwapChain->GetTexture()->GetRenderTargetView();
 
    // Set the viewport
    D3D11_VIEWPORT vp;
    vp.Height = static_cast<float>(pSwapChain->GetTexture()->GetSize().Height);
    vp.Width = static_cast<float>(pSwapChain->GetTexture()->GetSize().Width);
    vp.TopLeftX = 0.f;
    vp.TopLeftY = 0.f;
    vp.MinDepth = 0.f;
    vp.MaxDepth = 1.f;
    d3dImmediateContext->RSSetViewports( 1, &vp );
 
    ///
    /// Shaders setup
    ///
    kT::D3D11Shader* vs;
 
    // Load, compile, and create the vertex shader.
    try{
        vs = kT::D3D11Shader::LoadFromFile(
            device->GetHandle(),
            "raymarching.vsh",
            kT::D3D11Shader::VertexShader,
            kT::D3D11Shader::Profile4,
            "vsMain" );
 
    } catch( kT::Exception& e )
    {
        logger->Log( kT::Logger::CriticalErrorMessage, e.what() );
        return -10;
    }
 
    kT::D3D11Shader* ps;
    // Load, compile, and create the pixel shader.
    try{
        ps = kT::D3D11Shader::LoadFromFile(
            device->GetHandle(),
            "raymarching.psh",
            kT::D3D11Shader::PixelShader,
            kT::D3D11Shader::Profile4,
            "psMain" );
    }catch( std::exception& e )
    {
        logger->Log( kT::Logger::CriticalErrorMessage, e.what() );
        return -10;
    }
    ///
    /// Shader setup end.
    ///
 
    ///
    /// Geometry setup
    ///
 
    kT::Vector3f32 vertices[] = {
        kT::Vector3f32( -1.f, 1.f, 0.5f ),
        kT::Vector3f32( 1.f, 1.f, 0.5f ),
        kT::Vector3f32( 1.f, -1.f, 0.5f ),
        kT::Vector3f32( -1.f, -1.f, 0.5f )
    };
 
    kT::D3D11HardwareBuffer* vb = device->CreateBuffer(
        kT::D3D11HardwareBuffer::VertexBuffer,
        kT::D3D11HardwareBuffer::ImmutableBuffer,
        0,
        sizeof(kT::Vector3f32) * 4,
        vertices );
 
    unsigned short indices[] = {
        0, 1, 2,
        0, 2, 3
    };
 
    kT::D3D11HardwareBuffer* ib = device->CreateBuffer(
        kT::D3D11HardwareBuffer::IndexBuffer,
        kT::D3D11HardwareBuffer::ImmutableBuffer,
        0,
        sizeof(unsigned short) * 6,
        indices );
 
    kT::InputElementDesc layout[] = {
        { 0, kT::PositionElement, 0, kT::PixelFormat::RGB32_FLOAT, 0, kT::PerVertex }
    };
 
    kT::InputLayoutDesc layoutDesc = {
        1,
        layout,
    };
 
    kT::D3D11InputLayout* inputLayout = device->CreateLayout( vs, layoutDesc );
 
    size_t strides[16];
    inputLayout->ComputeStrides( strides );
    size_t offsets[16];
    memset( offsets, 0, sizeof(size_t) * 16 );
    ///
    ///
    ///
 
    /// General constants buffers
    float GradientEpsilon = 0.25f;
    struct WindowConstantBufferPS
    {
        kT::Vector3f32 dx;
        float minDist;
        kT::Vector3f32 dy;
        kT::Uint32 maxSteps;
        kT::Vector3f32 dz;
        float stepMultiplier;
    };
    WindowConstantBufferPS cbuffContentps;
    cbuffContentps.dx = kT::Vector3f32( GradientEpsilon, 0.f, 0.f );
    cbuffContentps.minDist = 0.001f;
    cbuffContentps.dy = kT::Vector3f32( 0.f, GradientEpsilon, 0.f );
    cbuffContentps.maxSteps = 100;
    cbuffContentps.dz = kT::Vector3f32( 0.f, 0.f, GradientEpsilon );
    cbuffContentps.stepMultiplier = 0.9f;
 
    kT::D3D11HardwareBuffer* windowConstants = device->CreateBuffer(
        kT::D3D11HardwareBuffer::ConstantBuffer,
        kT::D3D11HardwareBuffer::DefaultBuffer,
        0,
        sizeof(WindowConstantBufferPS),
        reinterpret_cast<void*>(&cbuffContentps));
    d3dImmediateContext->UpdateSubresource( windowConstants->GetHandle(), 0, 0, &cbuffContentps, 0, 0);
 
 
    // Light constants buffer
    struct LightBufferPS
    {
		kT::Vector3f32 LightDir;
        float pad;
        kT::Vector4f32 padl;
        kT::Vector4f32 padl1;
        kT::Vector4f32 padl2;
 
    };
    LightBufferPS lContentps;
    lContentps.LightDir = kT::Vector3f32(-0.5f, -1.f, 0.f).Normalize();
 
    kT::D3D11HardwareBuffer* lightConstants = device->CreateBuffer(
        kT::D3D11HardwareBuffer::ConstantBuffer,
        kT::D3D11HardwareBuffer::DefaultBuffer,
        0,
        sizeof(LightBufferPS),
        reinterpret_cast<void*>(&lContentps));
    d3dImmediateContext->UpdateSubresource( lightConstants->GetHandle(), 0, 0, &lContentps, 0, 0);
 
    // Camera constants buffer
    struct CameraBuffer
    {
        kT::Vector3f32 vecRight;
        kT::Vector3f32 vecUp;
        kT::Vector3f32 vecFwd;
        kT::Vector3f32 vecCamPos;
        float fov;
        kT::Vector3f32 pad;
    };
    CameraBuffer camContentps;
 
    	// Position camera
	kT::Vector3f32 vecCamTo = kT::Vector3f32(0.f,
							0.f,
							0.f);
 
	// Figure out view vectors from camera position
	camContentps.vecUp = kT::Vector3f32(0.f, 1.f, 0.f);
	camContentps.fov = 1.0f;
 
    kT::D3D11HardwareBuffer* camConstants = device->CreateBuffer(
        kT::D3D11HardwareBuffer::ConstantBuffer,
        kT::D3D11HardwareBuffer::DefaultBuffer,
        0,
        sizeof(CameraBuffer),
        reinterpret_cast<void*>(&camContentps.vecRight.x));
 
    bool opened = true;
 
     kT::Clock clock;
 
    window->EnableKeyRepeat(true);
    while( opened )
    {
        float dt = (float)clock.GetTimeElapsed();
        clock.Reset();
 
        window->ProcessEvents();
        kT::GUIEvent evt;
        while( window->GetEvent(evt) )
        {
            if( evt.Type == kT::GUIEvent::Closed
                || (evt.Type == kT::GUIEvent::KeyPressed
                && evt.Key.Code == kT::Key::Escape) )
                opened = false;
        }
 
    	// Position camera
        float g_fTime = clock.GetTimeElapsed() * 1000.f;
        camContentps.vecCamPos = kT::Vector3f32(25.f * sin(g_fTime * 0.001f),
						        21.f * sin(g_fTime * 0.0002f),
						        25.f * cos(g_fTime * 0.001f));
 
        // Figure out view vectors from camera position
        camContentps.vecFwd = (vecCamTo-camContentps.vecCamPos).Normalize();
        camContentps.vecRight = camContentps.vecFwd.Cross(camContentps.vecUp);
        camContentps.vecUp = camContentps.vecRight.Cross(camContentps.vecFwd);
 
        d3dImmediateContext->UpdateSubresource( camConstants->GetHandle(), 0, 0, &camContentps.vecRight.x, 0, 0);
 
        float color[4] = { 0.f, 0.f, 0.f, 0.f };
        d3dImmediateContext->ClearRenderTargetView( renderTargetView, color );
 
        immediateContext->IASetInputLayout( inputLayout );
        immediateContext->IASetPrimitiveTopology( kT::PrimitiveTopology::TriangleList );
        immediateContext->VSSetShader( vs );
        immediateContext->PSSetShader( ps );
        immediateContext->PSSetConstantBuffers( 0, 1, &windowConstants );
        immediateContext->PSSetConstantBuffers( 1, 1, &lightConstants );
        immediateContext->PSSetConstantBuffers( 2, 1, &camConstants );
        immediateContext->IASetIndexBuffer( ib, kT::PixelFormat::R16_UINT, 0 );
        immediateContext->IASetVertexBuffers( 0, 1, &vb, strides, offsets );
        immediateContext->DrawIndexed( 6, 0, 0 );
 
        pSwapChain->Present();
    }
 
	immediateContext->ClearState();
 
    delete inputLayout;
    delete ib;
    delete vb;
	delete ps;
	delete vs;
	delete pSwapChain;
	delete device;
 
    delete logger;
    delete window;
    return 0;
}

Le vertex shader (tout court, promis):
raymarch.vsh:

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struct VS_OUTPUT
{
    float4 Pos: SV_POSITION;
    float2 uv : TEXCOORD0;
};
 
VS_OUTPUT vsMain( float4 Pos : POSITION )
{
    VS_OUTPUT output;
    output.Pos = Pos;
    output.uv = 0.5f * Pos + 0.5f;
    output.uv.y = 1.0f - output.uv.y;
    return output;
}

le pixel shader (beaucoup plus long)
raymarch.psh

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cbuffer WindowConstantBufferPS
{
	float3 dx;
    float minDist;
	float3 dy;
	uint maxSteps;
	float3 dz;
	float stepMultiplier;
};
 
cbuffer LightBuffer
{
    float3 vecLightDir1;
    float padl;
    float4 padl1;
    float4 padl2;
    float4 padl3;
};
 
cbuffer CameraBuffer
{
    float3 s_vecRight;
    float3 s_vecUp;
    float3 s_vecFwd;
    float3 s_vecCamPos;
    float s_fFov;
    float3 pad1;
};
 
float rmSphere( in float3 f, in float fRadius )
{
	return length(f) - fRadius;
}
 
float rmRoundedCube( in float3 f, in float fSize, in float fRadius )
{
	float3 fD = max( abs(f) - fSize + fRadius, float3( 0.0f, 0.0f, 0.0f ) );
	return length( fD ) - fRadius;
}
 
 
float getDistance( in float3 vecPos)
{
    float fSphereDist1 = rmSphere(vecPos - float3( 5.f, 0.f, 0.f ), 4.f);
	float fSphereDist2 = rmSphere(vecPos + float3( 5.f, 0.f, 0.f ), 4.f);
	float fSphereDist3 = rmSphere(vecPos - float3( 0.f, 5.f, 0.f ), 4.f);
	float fSphereDist4 = rmSphere(vecPos + float3( 0.f, 5.f, 0.f ), 4.f);
	float fSphereDist5 = rmSphere(vecPos - float3( 0.f, 0.f, 5.f ), 4.f);
	float fSphereDist6 = rmSphere(vecPos + float3( 0.f, 0.f, 5.f ), 4.f);
	float fMinSphereDist = min( min( min( fSphereDist1, fSphereDist2 ), fSphereDist3 ), min( min(fSphereDist4, fSphereDist5), fSphereDist6 ) );
	float fCubeDist = rmRoundedCube(vecPos.xyz, 6.f, 2.f);
	return max(fCubeDist, -fMinSphereDist);
}
 
float3 gradient( in float3 f)
{
	return float3(
		getDistance(f + dx) - getDistance(f - dx),
		getDistance(f + dy) - getDistance(f - dy),
		getDistance(f + dz) - getDistance(f - dz)
	);
}
 
// r.x : fDist
// r.y complexity
float2 rayMarch( in float3 vecPos, in float3 vecDir )
{
	float3 vecCurrentPos = vecPos;
 
	float fDist = minDist;
	uint Step;
	for (Step = 0; (Step < maxSteps) && (fDist >= minDist); Step++ )
	{
		fDist = getDistance( vecCurrentPos );
        vecCurrentPos += (fDist * stepMultiplier) * vecDir;
		if(fDist > 100.f)
			return float2( 0.0f, 0.0f );
	}
 
	if ( fDist < minDist )
        {
/////////////// Branche A
		return float2( length(vecPos-vecCurrentPos), 1.f/float(Step) );
        }
	else
               return float2( 0.f, 0.f );
}
 
float3 shade( in float3 contactPos, in float3 camRay, in float2 rayMarchResult)
{
	float3 norm = gradient( contactPos );
	float fDiffTerm = saturate( dot( norm, vecLightDir1 ) );
    float3 f = fDiffTerm * float3( 1.5f, 1.5f, 1.5f ) + float3( 0.f, 0.f, 0.3f );
 
    return saturate( f );
}
 
float3 render( in float2 uv )
{
    float3 vecCamRight = (( uv.x - 0.5f) * s_fFov) * s_vecRight;
    float3 vecCamUp = ((uv.y - 0.5f) * s_fFov) * s_vecUp;
    float3 vecCamDir = vecCamRight + vecCamUp + s_vecFwd;
    vecCamDir = normalize( vecCamDir );
 
    float2 rayMarchResult = rayMarch( s_vecCamPos, vecCamDir );
    float fDistance = rayMarchResult.x;
 
    float3 c;
    if ( fDistance > 0.f )
    {
///////////////// Branche B
        // Ray hit our field - calculate the colour
        float3 vecContactPos = s_vecCamPos + (fDistance * vecCamDir);
        c = shade(vecContactPos, vecCamDir, rayMarchResult);
    }
    else
    {
        // Ray didn't hit anything - get background colour
        c = float3( 0.5f, 0.f, 1.0f );
    }
 
    return c;
}
 
struct VS_OUTPUT
{
    float4 Pos: SV_POSITION;
    float2 uv : TEXCOORD0;
};
 
float4 psMain( VS_OUTPUT output ) : SV_Target
{
    float3 c = render( output.uv );
    return float4( c.x, c.y, c.z, 1.f );
    return float4( output.uv.x, output.uv.y, 0.f, 1.f );
}

J'ai remarqué (en débuguant avec PIX et GPUPerfStudio) que même si l'on passe dans la branche que j'ai noté Branche A de rayMarch(), on arrive jamais dans la branche B de render(), le problème vient de là. (la branche B est la celle à pouvoir affecter autre chose que la couleur du fond).

Est-ce que vous auriez une idée?
Toute idée est la bien venue :)

Merci!

08/05/2013, 01h36
stardeath

comme ça je vois pas grand chose ... par contre c'est quoi ce kT (j'ai demandé à google mais il m'a envoyé balader)
08/05/2013, 09h16
khazna

kT ça devait être à l'origine mon moteur de jeu perso, multi plateformes (D3D11 OpenGL3/ Windows Linux) :aie:. Mais pour l'instant c'est surtout un petit truc pour faire des fenêtres à partir de SFML, avoir deux trois petites classes pour les matrices/vecteurs, et une petite surcouche D3D11.
08/05/2013, 11h27
LittleWhite

Avez-vous tenter d'écrire les valeurs directement dans le frame buffer, je veux dire, pour connaître les valeurs qu'elles ont en les affichant, cela aide au débugging. Par exemple, vous pouvais le faire pour fDistance et rayMarchResult.

De la même manière, vous pouvez vérifier chacune des condition (savoir ou passe votre code) pour préciser l'origine de l'erreur.
08/05/2013, 22h20
khazna

Je vais essayer de faire ça. ça va pas être de la tarte à débugger j'ai l'impression :calim2:...
D'après mes essais de debugging, getDistance() ne renvoit pas du tout ce qu'elle est sensée renvoyer... Pourtant les paramètres qui lui sont passés semblent correspondre à la version cpu...

C'est bon j'ai réussi à corriger mon problème!

Le bug venait du fait que côté shader le constant buffer n'était pas structuré de la manière dont je le pensais:
- si des variables d'un constant buffer ne sont pas utilisées, elles sont supprimées (d'où un debuggage difficile, vu que les variables utilisées n'étaient pas au même endroit dans le GPU qu'au CPU)
- j'ai passé tout les float3 en float4, parce que les offsets dans le constant buffer côté GPU n'étaient pas les mêmes que ceux dans le buffer CPU (les float3 prenaient 16 octets côté shader au lieu de 12 côté CPU).

Mais ça marche!

D'où au final le code suivant:

raymarch.psh

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cbuffer All
{
	float4 dx;
	float4 dy;
	float4 dz;
    float4 vecLightDir1;
    float4 s_vecRight;
    float4 s_vecUp;
    float4 s_vecFwd;
    float4 s_vecCamPos;
    float s_fFov;
    float minDist;
	uint maxSteps;
    float stepMultiplier;
};
 
float rmSphere( in float4 f, in float fRadius )
{
    return length(f) - fRadius;
}
 
float rmRoundedCube( in float4 f, in float fSize, in float fRadius )
{
    float4 v = float4( fRadius - fSize, fRadius - fSize, fRadius - fSize, 0.f );
    float4 fD = max( abs(f) + v, float4( 0.0f, 0.0f, 0.0f, 0.f ) );
    return length( fD ) - fRadius;
}
 
 
float getDistance( in float4 vecPos)
{
    float fSphereDist1 = rmSphere(vecPos - float4( 5.f, 0.f, 0.f, 0.f ), 4.f);
	float fSphereDist2 = rmSphere(vecPos + float4( 5.f, 0.f, 0.f, 0.f ), 4.f);
	float fSphereDist3 = rmSphere(vecPos - float4( 0.f, 5.f, 0.f, 0.f ), 4.f);
	float fSphereDist4 = rmSphere(vecPos + float4( 0.f, 5.f, 0.f, 0.f ), 4.f);
	float fSphereDist5 = rmSphere(vecPos - float4( 0.f, 0.f, 5.f, 0.f ), 4.f);
	float fSphereDist6 = rmSphere(vecPos + float4( 0.f, 0.f, 5.f, 0.f ), 4.f);
	float fMinSphereDist = min( min( min( fSphereDist1, fSphereDist2 ), fSphereDist3 ), min( min( fSphereDist4, fSphereDist5 ), fSphereDist6 ));
	float fCubeDist = rmRoundedCube(vecPos, 6.f, 2.f);
	return max(fCubeDist, -fMinSphereDist);
}
 
float4 gradient( in float4 f)
{
    return float4(
        getDistance(f + dx) - getDistance(f - dx),
        getDistance(f + dy) - getDistance(f - dy),
        getDistance(f + dz) - getDistance(f - dz),
        0.f
    );
}
 
// r.x : fDist
// r.y complexity
float2 rayMarch( in float4 vecPos, in float4 vecDir )
{
    float4 vecCurrentPos = vecPos;
 
    float fDist = minDist;
    uint Step = 0;
    for (Step = 0; (Step < maxSteps) && (fDist >= minDist); Step++ )
    {
        fDist = getDistance( vecCurrentPos );
 
        if(fDist > 100.f)
            return float2( 0.0f, 0.0f );
 
        vecCurrentPos += (fDist * stepMultiplier) * vecDir;
    }
 
    if ( fDist < minDist )
    {
        return float2( length(vecPos-vecCurrentPos), 1.f/float(Step) );
    }
    else
        return float2( 0.f, 0.f );
}
 
float3 shade( in float4 contactPos, in float4 camRay, in float2 rayMarchResult)
{
    float4 norm = gradient( contactPos );
    float fDiffTerm = saturate( dot( norm, vecLightDir1 ) );
    float3 f = fDiffTerm * float3( 1.5f, 1.5f, 1.5f ) + float3( 0.f, 0.f, 0.03f );
 
    return saturate( f );
}
 
float3 render( in float2 uv )
{
 
    float4 vecCamRight = (( uv.x - 0.5f) * s_fFov) * s_vecRight;
    float4 vecCamUp = ((uv.y - 0.5f) * s_fFov) * s_vecUp;
    float4 vecCamDir = normalize( vecCamRight + vecCamUp + s_vecFwd );
 
    float2 rayMarchResult = rayMarch( s_vecCamPos, vecCamDir );
 
    float fDistance = rayMarchResult.x;
 
    if ( fDistance > 0.f )
    {
        // Ray hit our field - calculate the colour
        float4 vecContactPos = s_vecCamPos + (fDistance * vecCamDir);
        return shade(vecContactPos, vecCamDir, rayMarchResult);
    }
    else
    {
        // Ray didn't hit anything - get background colour
        return float3( 0.5f, 0.f, 1.0f );
    }
}
 
struct VS_OUTPUT
{
    float4 Pos: SV_POSITION;
    float2 uv : TEXCOORD0;
};
 
float4 psMain( VS_OUTPUT output ) : SV_Target
{
    float3 c = render( output.uv );
    return float4( c.x, c.y, c.z, 1.f );
}

raymarch.vsh

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struct VS_OUTPUT
{
    float4 Pos: SV_POSITION;
    float2 uv : TEXCOORD0;
};
 
VS_OUTPUT vsMain( float4 Pos : POSITION )
{
    VS_OUTPUT output;
    output.Pos = Pos;
    output.uv = 0.5f * Pos + 0.5f;
    output.uv.y = 1.0f - output.uv.y;
    return output;
}

main.cpp

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#include <kT/Core.hpp>
#include <kT/Math.hpp>
#include <kT/Window.hpp>
 
#include <kT/Graphics/D3D11Device/D3D11Device.hpp>
#include <kT/Graphics/D3D11Device/D3D11Shader.hpp>
#include <kT/Graphics/D3D11Device/D3D11SwapChain.hpp>
#include <kT/Graphics/D3D11Device/D3D11ImmediateContext.hpp>
#include <kT/Graphics/D3D11Device/D3D11DeviceTypes.hpp>
#include <kT/Graphics/D3D11Device/D3D11Texture.hpp>
 
#include <D3D11.h>
 
int main( int argc, char** argv )
{
    kT::FileLogger* logger = new kT::FileLogger;
 
    kT::VideoMode mode = kT::VideoMode::GetDesktopMode();
#ifdef NDEBUG
    kT::Window* window = new kT::Window("Ray", kT::Sizeui32(1680, 1050), kT::Window::Overlapped );
#else
    kT::Window* window = new kT::Window("Ray", kT::Sizeui32(1680, 1050), kT::Window::Overlapped );
#endif
    window->Show();
 
    kT::D3D11Device* device;
    kT::D3D11ImmediateContext* immediateContext = 0;
    ID3D11Device* d3dDevice = 0;
    ID3D11DeviceContext* d3dImmediateContext = 0;
 
    try{
#ifndef NDEBUG
    try{
        device = new kT::D3D11Device(kT::GraphicsDevice< kTD3D11DeviceTemplateListLineTypes >::HardwareProcessing, true);
    } catch( kT::Exception& e )
    {
        device = new kT::D3D11Device();
    }
 
#else
	device = new kT::D3D11Device();
#endif
        immediateContext = device->GetImmediateContext();
        d3dDevice = device->GetHandle();
        d3dImmediateContext = immediateContext->GetHandle();;
        if( device->GetFeatureLevel() == D3D_FEATURE_LEVEL_11_0 )
            logger->Log( kT::Logger::InfoMessage, "Feature level 11!" );
    } catch( kT::Exception& e )
    {
        logger->Log( kT::Logger::CriticalErrorMessage, "Can't create the device");
        return -1;
    }
 
    kT::D3D11SwapChain* pSwapChain;
    try{
        pSwapChain = new kT::D3D11SwapChain( d3dDevice, window, kT::PixelFormat::RGBA8_UNORM, window->GetSize(), true, 1 );
    } catch( kT::Exception& e )
    {
        logger->Log( kT::Logger::CriticalErrorMessage, "Can't create the swapchain" );
        return -1;
    }
 
    ID3D11RenderTargetView* renderTargetView = pSwapChain->GetTexture()->GetRenderTargetView();
    d3dImmediateContext->OMSetRenderTargets( 1, &renderTargetView, 0 );
 
    // Set the viewport
    D3D11_VIEWPORT vp;
    vp.Height = static_cast<float>(pSwapChain->GetTexture()->GetSize().Height);
    vp.Width = static_cast<float>(pSwapChain->GetTexture()->GetSize().Width);
    vp.TopLeftX = 0.f;
    vp.TopLeftY = 0.f;
    vp.MinDepth = 0.f;
    vp.MaxDepth = 1.f;
    d3dImmediateContext->RSSetViewports( 1, &vp );
 
    ///
    /// Shaders setup
    ///
    kT::D3D11Shader* vs;
 
    // Load, compile, and create the vertex shader.
    try{
        vs = kT::D3D11Shader::LoadFromFile(
            device->GetHandle(),
            "raymarching.vsh",
            kT::D3D11Shader::VertexShader,
            kT::D3D11Shader::Profile4,
            "vsMain" );
 
    } catch( kT::Exception& e )
    {
        logger->Log( kT::Logger::CriticalErrorMessage, e.what() );
        return -10;
    }
 
    kT::D3D11Shader* ps;
    // Load, compile, and create the pixel shader.
    try{
        ps = kT::D3D11Shader::LoadFromFile(
            device->GetHandle(),
            "raymarching.psh",
            kT::D3D11Shader::PixelShader,
            kT::D3D11Shader::Profile4,
            "psMain" );
    }catch( std::exception& e )
    {
        logger->Log( kT::Logger::CriticalErrorMessage, e.what() );
        return -10;
    }
    ///
    /// Shader setup end.
    ///
 
    ///
    /// Geometry setup
    ///
 
    kT::Vector3f32 vertices[] = {
        kT::Vector3f32( -1.f, 1.f, 0.5f ),
        kT::Vector3f32( 1.f, 1.f, 0.5f ),
        kT::Vector3f32( 1.f, -1.f, 0.5f ),
        kT::Vector3f32( -1.f, -1.f, 0.5f )
    };
 
    kT::D3D11HardwareBuffer* vb = device->CreateBuffer(
        kT::D3D11HardwareBuffer::VertexBuffer,
        kT::D3D11HardwareBuffer::ImmutableBuffer,
        0,
        sizeof(kT::Vector3f32) * 4,
        vertices );
 
    unsigned short indices[] = {
        0, 1, 2,
        0, 2, 3
    };
 
    kT::D3D11HardwareBuffer* ib = device->CreateBuffer(
        kT::D3D11HardwareBuffer::IndexBuffer,
        kT::D3D11HardwareBuffer::ImmutableBuffer,
        0,
        sizeof(unsigned short) * 6,
        indices );
 
    kT::InputElementDesc layout[] = {
        { 0, kT::PositionElement, 0, kT::PixelFormat::RGB32_FLOAT, 0, kT::PerVertex }
    };
 
    kT::InputLayoutDesc layoutDesc = {
        1,
        layout,
    };
 
    kT::D3D11InputLayout* inputLayout = device->CreateLayout( vs, layoutDesc );
 
    size_t strides[16];
    inputLayout->ComputeStrides( strides );
    size_t offsets[16];
    memset( offsets, 0, sizeof(size_t) * 16 );
    ///
    ///
    ///
 
    /// General constants buffers
    float GradientEpsilon = 0.25f;
    struct ConstantBufferPS
    {
        kT::Vector4f32 dx;
        kT::Vector4f32 dy;
        kT::Vector4f32 dz;
        kT::Vector4f32 LightDir;
        kT::Vector4f32 vecRight;
        kT::Vector4f32 vecUp;
        kT::Vector4f32 vecFwd;
        kT::Vector4f32 vecCamPos;
        float fov;
        float minDist;
        kT::Uint32 maxSteps;
        float stepMultiplier;
        kT::Vector4f32 pad;
    };
    ConstantBufferPS cbuffContentps;
    cbuffContentps.dx = kT::Vector4f32( GradientEpsilon, 0.f, 0.f, 0.f );
    cbuffContentps.minDist = 0.001f;
    cbuffContentps.dy = kT::Vector4f32( 0.f, GradientEpsilon, 0.f, 0.f );
    cbuffContentps.maxSteps = 100;
    cbuffContentps.dz = kT::Vector4f32( 0.f, 0.f, GradientEpsilon, 0.f );
    cbuffContentps.stepMultiplier = 0.9f;
    cbuffContentps.LightDir = kT::Vector4f32(-0.5f, -1.f, 0.f, 0.f).Normalize();
 
    cbuffContentps.vecUp = kT::Vector4f32(0.f, 1.f, 0.f, 0.f);
    cbuffContentps.fov = 1.0f;
    cbuffContentps.vecCamPos = kT::Vector4f32(22.340927f,
						20.909090f,
						11.219760f,
                        0.f );
 
    // Figure out view vectors from camera position
    kT::Vector4f32 vecCamTo( 0.f, 0.f, 0.f, 0.f );
    cbuffContentps.vecFwd = (vecCamTo-cbuffContentps.vecCamPos).Normalize();
 
    kT::Vector3f32 fwd3( cbuffContentps.vecFwd.x, cbuffContentps.vecFwd.y, cbuffContentps.vecFwd.z );
    kT::Vector3f32 up3( cbuffContentps.vecUp.x, cbuffContentps.vecUp.y, cbuffContentps.vecUp.z );
    kT::Vector3f32 right3 = fwd3.Cross(up3);
    up3 = right3.Cross(fwd3);
 
    cbuffContentps.vecRight = kT::Vector4f32( right3.x, right3.y, right3.z, 0.f );
    cbuffContentps.vecUp = kT::Vector4f32( up3.x, up3.y, up3.z, 0.f );
 
    kT::D3D11HardwareBuffer* constants = device->CreateBuffer(
        kT::D3D11HardwareBuffer::ConstantBuffer,
        kT::D3D11HardwareBuffer::DefaultBuffer,
        0,
        sizeof(ConstantBufferPS),
        reinterpret_cast<void*>(&cbuffContentps));
    d3dImmediateContext->UpdateSubresource( constants->GetHandle(), 0, 0, &cbuffContentps, 0, 0);
 
    bool opened = true;
 
        kT::Clock clock;
 
    window->EnableKeyRepeat(true);
 
    while( opened )
    {
        window->ProcessEvents();
        kT::GUIEvent evt;
        while( window->GetEvent(evt) )
        {
            if( evt.Type == kT::GUIEvent::Closed
                || (evt.Type == kT::GUIEvent::KeyPressed
                && evt.Key.Code == kT::Key::Escape) )
                opened = false;
        }
 
        float g_fTime = clock.GetTimeElapsed() * 1000.f;
 
        cbuffContentps.vecCamPos = kT::Vector4f32(
                        25.f * sin(g_fTime * 0.001f),
						21.f * sin(g_fTime * 0.0002f),
						25.f * cos(g_fTime * 0.001f),
                        0.f );
 
        // Figure out view vectors from camera position
        kT::Vector4f32 vecCamTo( 0.f, 0.f, 0.f, 0.f );
        cbuffContentps.vecFwd = (vecCamTo-cbuffContentps.vecCamPos).Normalize();
 
        kT::Vector3f32 fwd3( cbuffContentps.vecFwd.x, cbuffContentps.vecFwd.y, cbuffContentps.vecFwd.z );
        kT::Vector3f32 up3( cbuffContentps.vecUp.x, cbuffContentps.vecUp.y, cbuffContentps.vecUp.z );
        kT::Vector3f32 right3 = fwd3.Cross(up3);
        up3 = right3.Cross(fwd3);
 
        cbuffContentps.vecRight = kT::Vector4f32( right3.x, right3.y, right3.z, 0.f );
        cbuffContentps.vecUp = kT::Vector4f32( up3.x, up3.y, up3.z, 0.f );
 
        d3dImmediateContext->UpdateSubresource( constants->GetHandle(), 0, 0, &cbuffContentps, 0, 0);
 
        float color[4] = { 0.f, 0.f, 0.f, 0.f };
        d3dImmediateContext->ClearRenderTargetView( renderTargetView, color );
 
        immediateContext->IASetInputLayout( inputLayout );
        immediateContext->IASetPrimitiveTopology( kT::PrimitiveTopology::TriangleList );
        immediateContext->VSSetShader( vs );
        immediateContext->PSSetShader( ps );
        immediateContext->PSSetConstantBuffers( 0, 1, &constants );
        immediateContext->IASetIndexBuffer( ib, kT::PixelFormat::R16_UINT, 0 );
        immediateContext->IASetVertexBuffers( 0, 1, &vb, strides, offsets );
        immediateContext->DrawIndexed( 6, 0, 0 );
 
        pSwapChain->Present();
    }
 
    immediateContext->ClearState();
 
    delete inputLayout;
    delete ib;
    delete vb;
    delete ps;
    delete vs;
    delete pSwapChain;
    delete device;
 
    delete logger;
    delete window;
    return 0;
}

(Au cas où quelqu'un voudrait essayer la technique).

Merci de votre aide :)