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0027925: Visualization - implement order-independent transparency algorithm within rasterization rendering

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Weighted, Blended Order-Independent Transparency algorithm has been added rasterization pipeline.
In contrast to classical blending transparency it makes transparent objects look independent
from point of view. It also gives better depth occlusion when being used together with a weight factor
based on value of a GL depth buffer. The feature supports desktop OpenGL, OpenGL ES 3.0, ANGLE
and can be used together with MSAA on desktop GL.

To be used it require availability of:
1) Shaders pipeline.
2) Floating point color format for framebuffer (GL_ARB_color_buffer_float).
3) Multiple render targets (GL_ARB_draw_buffers).

Patch does not modify API and does not require application porting.
It adds new rendering options to Graphic3d_RenderingParams structure:
a) Transparency method from enumeration.
b) Scalar factor [0-1] controlling influence of a fragment's depth to its visibility.

Patch also simplifies processing of transparent objects for standard method:
rendering priority of transparent graphical structures is managed automatically,
therefore there is no need to care about it at application's side.
This commit is contained in:
apl
2017-04-25 15:10:15 +03:00
committed by bugmaster
parent 9151562167
commit a1073ae267
41 changed files with 1947 additions and 299 deletions
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221
src/OpenGl/OpenGl_Context.cxx
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@@ -125,6 +125,11 @@ OpenGl_Context::OpenGl_Context (const Handle(OpenGl_Caps)& theCaps)
hasUintIndex(Standard_True),
hasTexRGBA8(Standard_True),
#endif
hasDrawBuffers (OpenGl_FeatureNotAvailable),
hasFloatBuffer (OpenGl_FeatureNotAvailable),
hasHalfFloatBuffer (OpenGl_FeatureNotAvailable),
hasSampleVariables (OpenGl_FeatureNotAvailable),
arbDrawBuffers (Standard_False),
arbNPTW (Standard_False),
arbTexRG (Standard_False),
arbTexFloat (Standard_False),
@@ -135,13 +140,16 @@ OpenGl_Context::OpenGl_Context (const Handle(OpenGl_Caps)& theCaps)
arbDbg (NULL),
arbFBO (NULL),
arbFBOBlit (NULL),
arbSampleShading (Standard_False),
extFragDepth (Standard_False),
extDrawBuffers (Standard_False),
extGS (NULL),
extBgra(Standard_False),
extAnis(Standard_False),
extPDS (Standard_False),
atiMem (Standard_False),
nvxMem (Standard_False),
oesSampleVariables (Standard_False),
mySharedResources (new OpenGl_ResourcesMap()),
myDelayed (new OpenGl_DelayReleaseMap()),
myUnusedResources (new OpenGl_ResourcesStack()),
@@ -153,6 +161,8 @@ OpenGl_Context::OpenGl_Context (const Handle(OpenGl_Caps)& theCaps)
myMaxTexDim (1024),
myMaxClipPlanes (6),
myMaxMsaaSamples(0),
myMaxDrawBuffers (1),
myMaxColorAttachments (1),
myGlVerMajor (0),
myGlVerMinor (0),
myIsInitialized (Standard_False),
@@ -172,7 +182,7 @@ OpenGl_Context::OpenGl_Context (const Handle(OpenGl_Caps)& theCaps)
#endif
myToCullBackFaces (false),
myReadBuffer (0),
myDrawBuffer (0),
myDrawBuffers (1),
myDefaultVao (0),
myIsGlDebugCtx (Standard_False),
myResolution (Graphic3d_RenderingParams::THE_DEFAULT_RESOLUTION),
@@ -394,18 +404,60 @@ void OpenGl_Context::SetReadBuffer (const Standard_Integer theReadBuffer)
void OpenGl_Context::SetDrawBuffer (const Standard_Integer theDrawBuffer)
{
#if !defined(GL_ES_VERSION_2_0)
myDrawBuffer = !myIsStereoBuffers ? stereoToMonoBuffer (theDrawBuffer) : theDrawBuffer;
if (myDrawBuffer < GL_COLOR_ATTACHMENT0
const Standard_Integer aDrawBuffer = !myIsStereoBuffers ? stereoToMonoBuffer (theDrawBuffer) : theDrawBuffer;
if (aDrawBuffer < GL_COLOR_ATTACHMENT0
&& arbFBO != NULL)
{
arbFBO->glBindFramebuffer (GL_FRAMEBUFFER, OpenGl_FrameBuffer::NO_FRAMEBUFFER);
}
::glDrawBuffer (myDrawBuffer);
::glDrawBuffer (aDrawBuffer);
myDrawBuffers.Clear();
if (aDrawBuffer != GL_NONE)
{
myDrawBuffers.SetValue (0, aDrawBuffer);
}
#else
(void )theDrawBuffer;
#endif
}
// =======================================================================
// function : SetDrawBuffers
// purpose :
// =======================================================================
void OpenGl_Context::SetDrawBuffers (const Standard_Integer theNb, const Standard_Integer* theDrawBuffers)
{
Standard_ASSERT_RETURN (hasDrawBuffers, "Multiple draw buffers feature is not supported by the context", Standard_ASSERT_DO_NOTHING());
myDrawBuffers.Clear();
Standard_Boolean useDefaultFbo = Standard_False;
for (Standard_Integer anI = 0; anI < theNb; ++anI)
{
#if !defined(GL_ES_VERSION_2_0)
const Standard_Integer aDrawBuffer = !myIsStereoBuffers ? stereoToMonoBuffer (theDrawBuffers[anI]) : theDrawBuffers[anI];
#else
const Standard_Integer aDrawBuffer = theDrawBuffers[anI];
#endif
if (aDrawBuffer < GL_COLOR_ATTACHMENT0 && aDrawBuffer != GL_NONE)
{
useDefaultFbo = Standard_True;
}
else if (aDrawBuffer != GL_NONE)
{
myDrawBuffers.SetValue (anI, aDrawBuffer);
}
}
if (arbFBO != NULL && useDefaultFbo)
{
arbFBO->glBindFramebuffer (GL_FRAMEBUFFER, OpenGl_FrameBuffer::NO_FRAMEBUFFER);
}
myFuncs->glDrawBuffers (theNb, (const GLenum*)theDrawBuffers);
}
// =======================================================================
// function : SetCullBackFaces
// purpose :
@@ -442,9 +494,37 @@ void OpenGl_Context::FetchState()
::glGetIntegerv (GL_RENDER_MODE, &myRenderMode);
}
// cache buffers state
// cache read buffers state
::glGetIntegerv (GL_READ_BUFFER, &myReadBuffer);
::glGetIntegerv (GL_DRAW_BUFFER, &myDrawBuffer);
// cache draw buffers state
myDrawBuffers.Clear();
if (myMaxDrawBuffers == 1)
{
Standard_Integer aDrawBuffer;
::glGetIntegerv (GL_DRAW_BUFFER, &aDrawBuffer);
if (aDrawBuffer != GL_NONE)
{
myDrawBuffers.SetValue (0, aDrawBuffer);
}
}
else
{
Standard_Integer aDrawBuffer;
for (Standard_Integer anI = 0; anI < myMaxDrawBuffers; ++anI)
{
::glGetIntegerv (GL_DRAW_BUFFER0 + anI, &aDrawBuffer);
if (aDrawBuffer != GL_NONE)
{
myDrawBuffers.SetValue (anI, aDrawBuffer);
}
}
}
#endif
}
@@ -1119,6 +1199,8 @@ void OpenGl_Context::init (const Standard_Boolean theIsCoreProfile)
myGlVerMajor = 0;
myGlVerMinor = 0;
myMaxMsaaSamples = 0;
myMaxDrawBuffers = 1;
myMaxColorAttachments = 1;
ReadGlVersion (myGlVerMajor, myGlVerMinor);
myVendor = (const char* )::glGetString (GL_VENDOR);
if (!caps->ffpEnable
@@ -1292,19 +1374,56 @@ void OpenGl_Context::init (const Standard_Boolean theIsCoreProfile)
}
}
extDrawBuffers = CheckExtension ("GL_EXT_draw_buffers") && FindProc ("glDrawBuffersEXT", myFuncs->glDrawBuffers);
arbDrawBuffers = CheckExtension ("GL_ARB_draw_buffers") && FindProc ("glDrawBuffersARB", myFuncs->glDrawBuffers);
if (IsGlGreaterEqual (3, 0) && FindProc ("glDrawBuffers", myFuncs->glDrawBuffers))
{
hasDrawBuffers = OpenGl_FeatureInCore;
}
else if (extDrawBuffers || arbDrawBuffers)
{
hasDrawBuffers = OpenGl_FeatureInExtensions;
}
hasFloatBuffer = IsGlGreaterEqual (3, 2) ? OpenGl_FeatureInCore :
CheckExtension ("GL_EXT_color_buffer_float") ? OpenGl_FeatureInExtensions
: OpenGl_FeatureNotAvailable;
hasHalfFloatBuffer = IsGlGreaterEqual (3, 2) ? OpenGl_FeatureInCore :
CheckExtension ("GL_EXT_color_buffer_half_float") ? OpenGl_FeatureInExtensions
: OpenGl_FeatureNotAvailable;
oesSampleVariables = CheckExtension ("GL_OES_sample_variables");
hasSampleVariables = IsGlGreaterEqual (3, 2) ? OpenGl_FeatureInCore :
oesSampleVariables ? OpenGl_FeatureInExtensions
: OpenGl_FeatureNotAvailable;
#else
myTexClamp = IsGlGreaterEqual (1, 2) ? GL_CLAMP_TO_EDGE : GL_CLAMP;
hasTexRGBA8 = Standard_True;
arbNPTW = CheckExtension ("GL_ARB_texture_non_power_of_two");
arbTexFloat = IsGlGreaterEqual (3, 0)
|| CheckExtension ("GL_ARB_texture_float");
extBgra = CheckExtension ("GL_EXT_bgra");
extAnis = CheckExtension ("GL_EXT_texture_filter_anisotropic");
extPDS = CheckExtension ("GL_EXT_packed_depth_stencil");
atiMem = CheckExtension ("GL_ATI_meminfo");
nvxMem = CheckExtension ("GL_NVX_gpu_memory_info");
arbDrawBuffers = CheckExtension ("GL_ARB_draw_buffers");
arbNPTW = CheckExtension ("GL_ARB_texture_non_power_of_two");
arbTexFloat = IsGlGreaterEqual (3, 0)
|| CheckExtension ("GL_ARB_texture_float");
arbSampleShading = CheckExtension ("GL_ARB_sample_shading");
extBgra = CheckExtension ("GL_EXT_bgra");
extAnis = CheckExtension ("GL_EXT_texture_filter_anisotropic");
extPDS = CheckExtension ("GL_EXT_packed_depth_stencil");
atiMem = CheckExtension ("GL_ATI_meminfo");
nvxMem = CheckExtension ("GL_NVX_gpu_memory_info");
hasDrawBuffers = IsGlGreaterEqual (2, 0) ? OpenGl_FeatureInCore :
arbDrawBuffers ? OpenGl_FeatureInExtensions
: OpenGl_FeatureNotAvailable;
hasFloatBuffer = hasHalfFloatBuffer = IsGlGreaterEqual (3, 0) ? OpenGl_FeatureInCore :
CheckExtension ("GL_ARB_color_buffer_float") ? OpenGl_FeatureInExtensions
: OpenGl_FeatureNotAvailable;
hasSampleVariables = IsGlGreaterEqual (4, 0) ? OpenGl_FeatureInCore :
arbSampleShading ? OpenGl_FeatureInExtensions
: OpenGl_FeatureNotAvailable;
GLint aStereo = GL_FALSE;
glGetIntegerv (GL_STEREO, &aStereo);
@@ -1314,6 +1433,12 @@ void OpenGl_Context::init (const Standard_Boolean theIsCoreProfile)
glGetIntegerv (GL_MAX_CLIP_PLANES, &myMaxClipPlanes);
#endif
if (hasDrawBuffers)
{
glGetIntegerv (GL_MAX_DRAW_BUFFERS, &myMaxDrawBuffers);
glGetIntegerv (GL_MAX_COLOR_ATTACHMENTS, &myMaxColorAttachments);
}
glGetIntegerv (GL_MAX_TEXTURE_SIZE, &myMaxTexDim);
if (extAnis)
@@ -2892,8 +3017,7 @@ Handle(OpenGl_FrameBuffer) OpenGl_Context::SetDefaultFrameBuffer (const Handle(O
// purpose :
// =======================================================================
void OpenGl_Context::SetShadingMaterial (const OpenGl_AspectFace* theAspect,
const Handle(Graphic3d_PresentationAttributes)& theHighlight,
const Standard_Boolean theUseDepthWrite)
const Handle(Graphic3d_PresentationAttributes)& theHighlight)
{
const Handle(Graphic3d_AspectFillArea3d)& anAspect = (!theHighlight.IsNull() && !theHighlight->BasicFillAreaAspect().IsNull())
? theHighlight->BasicFillAreaAspect()
@@ -2920,39 +3044,19 @@ void OpenGl_Context::SetShadingMaterial (const OpenGl_AspectFace* theAspect,
myMatBack = myMatFront;
}
// handling transparency
float aTranspFront = aMatFrontSrc.Transparency();
float aTranspBack = aMatBackSrc .Transparency();
if (!theHighlight.IsNull()
&& theHighlight->BasicFillAreaAspect().IsNull())
{
myMatFront.SetColor (theHighlight->ColorRGBA());
myMatBack .SetColor (theHighlight->ColorRGBA());
aTranspFront = theHighlight->Transparency();
aTranspBack = theHighlight->Transparency();
}
Standard_ShortReal aTranspFront = 0.f;
Standard_ShortReal aTranspBack = 0.f;
if (CheckIsTransparent (theAspect, theHighlight, aTranspFront, aTranspBack))
{
GLboolean aDepthMask = GL_TRUE;
if (aTranspFront != 0.0f
|| aTranspBack != 0.0f)
{
// render transparent
myMatFront.Diffuse.a() = 1.0f - aTranspFront;
myMatBack .Diffuse.a() = 1.0f - aTranspBack;
glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glEnable (GL_BLEND);
aDepthMask = GL_FALSE;
}
else
{
// render opaque
glBlendFunc (GL_ONE, GL_ZERO);
glDisable (GL_BLEND);
}
if (theUseDepthWrite)
{
glDepthMask (aDepthMask);
}
myMatFront.Diffuse.a() = 1.0f - aTranspFront;
myMatBack .Diffuse.a() = 1.0f - aTranspBack;
}
// do not update material properties in case of zero reflection mode,
@@ -2973,6 +3077,39 @@ void OpenGl_Context::SetShadingMaterial (const OpenGl_AspectFace* theAspect,
myShaderManager->UpdateMaterialStateTo (myMatFront, myMatBack, toDistinguish, toMapTexture);
}
// =======================================================================
// function : CheckIsTransparent
// purpose :
// =======================================================================
Standard_Boolean OpenGl_Context::CheckIsTransparent (const OpenGl_AspectFace* theAspect,
const Handle(Graphic3d_PresentationAttributes)& theHighlight,
Standard_ShortReal& theTranspFront,
Standard_ShortReal& theTranspBack)
{
const Handle(Graphic3d_AspectFillArea3d)& anAspect = (!theHighlight.IsNull() && !theHighlight->BasicFillAreaAspect().IsNull())
? theHighlight->BasicFillAreaAspect()
: theAspect->Aspect();
const bool toDistinguish = anAspect->Distinguish();
const Graphic3d_MaterialAspect& aMatFrontSrc = anAspect->FrontMaterial();
const Graphic3d_MaterialAspect& aMatBackSrc = toDistinguish
? anAspect->BackMaterial()
: aMatFrontSrc;
// handling transparency
theTranspFront = aMatFrontSrc.Transparency();
theTranspBack = aMatBackSrc .Transparency();
if (!theHighlight.IsNull()
&& theHighlight->BasicFillAreaAspect().IsNull())
{
theTranspFront = theHighlight->Transparency();
theTranspBack = theHighlight->Transparency();
}
return theTranspFront != 0.f
|| theTranspBack != 0.f;
}
// =======================================================================
// function : SetColor4fv
// purpose :