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OpenGL Renderer: Reduce the number of stencil bits needed to emulate the shadow volume mask from 2 to 1.

This commit is contained in:
rogerman 2017-10-09 14:05:53 -07:00
parent c9025e81cb
commit 2a1aaf727e
2 changed files with 34 additions and 36 deletions
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49
desmume/src/OGLRender.cpp
View File

@ -4127,20 +4127,19 @@ Render3DError OpenGLRenderer_1_2::SetupPolygon(const POLY &thePoly, bool treatAs
// how this 4-pass process works in OpenGL.
if (thePoly.attribute.PolygonID == 0)
{
// 1st pass: Mark stencil buffer bits (0x40) with the shadow polygon volume.
// Bits are only marked on depth-fail.
glStencilFunc(GL_ALWAYS, 0x40, 0xC0);
// 1st pass: Use stencil buffer bit 6 (0x40) for the shadow volume mask.
// Write only on depth-fail.
glStencilFunc(GL_ALWAYS, 0x40, 0x40);
glStencilOp(GL_KEEP, GL_REPLACE, GL_KEEP);
glStencilMask(0xC0);
glStencilMask(0x40);
}
else
{
// 2nd pass: Mark stencil buffer bits (0x80) with the result of the polygon ID
// check. Bits are marked if the polygon ID of this polygon differs from the
// one in the stencil buffer.
glStencilFunc(GL_NOTEQUAL, 0x80 | thePoly.attribute.PolygonID, 0x3F);
glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);
glStencilMask(0x80);
// 2nd pass: Compare stencil buffer bits 0-5 (0x3F) with this polygon's ID. If this stencil
// test fails, remove the fragment from the shadow volume mask by clearing bit 6.
glStencilFunc(GL_NOTEQUAL, thePoly.attribute.PolygonID, 0x3F);
glStencilOp(GL_ZERO, GL_KEEP, GL_KEEP);
glStencilMask(0x40);
}
glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);
@ -4150,7 +4149,7 @@ Render3DError OpenGLRenderer_1_2::SetupPolygon(const POLY &thePoly, bool treatAs
{
glStencilFunc(GL_ALWAYS, thePoly.attribute.PolygonID, 0x3F);
glStencilOp(GL_KEEP, GL_KEEP, (treatAsTranslucent) ? GL_KEEP : GL_REPLACE);
glStencilMask(0xFF); // Drawing non-shadow polygons will implicitly reset the stencil buffer bits
glStencilMask(0x7F); // Drawing non-shadow polygons will implicitly reset the shadow volume mask.
glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
glDepthMask((!treatAsTranslucent || thePoly.attribute.TranslucentDepthWrite_Enable) ? GL_TRUE : GL_FALSE);
@ -4266,7 +4265,7 @@ Render3DError OpenGLRenderer_1_2::DrawShadowPolygon(const GLenum polyPrimitive,
// Note that the 1st and 2nd passes are performed using states from SetupPolygon().
//
// 1st pass (NDS driven): The NDS creates the shadow volume and updates only the
// stencil buffer, writing to bit 0x40. Color and depth writes are disabled for this
// stencil buffer, writing to bit 6 (0x40). Color and depth writes are disabled for this
// pass.
//
// 2nd pass (NDS driven): Normally, stencil buffer bits marked for shadow rendering
@ -4275,13 +4274,13 @@ Render3DError OpenGLRenderer_1_2::DrawShadowPolygon(const GLenum polyPrimitive,
// one type of stencil buffer check at a time, we need to do things differently from
// what the NDS does at this point. In OpenGL, this pass is used only to update the
// stencil buffer for the polygon ID check, checking bits 0x3F for the polygon ID,
// and writing the result to bit 0x80. Color and depth writes are disabled for this
// pass.
// and clearing bit 6 (0x40) if this check fails. Color and depth writes are disabled
// for this pass.
//
// 3rd pass (emulator driven): Check both stencil buffer bits 0x80 (the polygon ID
// check) and 0x40 (the shadow volume definition), and render the shadow polygons only
// if both bits are set. Color writes are always enabled and depth writes are enabled
// if the shadow polygon is opaque or if transparent polygon depth writes are enabled.
// 3rd pass (emulator driven): Use stencil buffer bit 6 (0x40) for the shadow volume
// mask and render the shadow polygons only within the mask. Color writes are always
// enabled and depth writes are enabled if the shadow polygon is opaque or if transparent
// polygon depth writes are enabled.
//
// 4th pass (emulator driven): This pass only occurs when the shadow polygon is opaque.
// Since opaque polygons need to update their polygon IDs, we update only the stencil
@ -4298,12 +4297,12 @@ Render3DError OpenGLRenderer_1_2::DrawShadowPolygon(const GLenum polyPrimitive,
glDrawElements(polyPrimitive, vertIndexCount, GL_UNSIGNED_SHORT, indexBufferPtr);
// 3rd pass: Draw the shadow polygon.
glStencilFunc(GL_EQUAL, 0xC0, 0xC0);
// Technically, a depth-fail result should also reset the stencil buffer bits, but
// Mario Kart DS draws shadow polygons better when it doesn't reset bits on depth-fail.
glStencilFunc(GL_EQUAL, 0x40, 0x40);
// Technically, a depth-fail result should also clear the shadow volume mask, but
// Mario Kart DS draws shadow polygons better when it doesn't clear bits on depth-fail.
// I have no idea why this works. - rogerman 2016/12/21
glStencilOp(GL_ZERO, GL_KEEP, GL_ZERO);
glStencilMask(0xC0);
glStencilMask(0x40);
glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
glDepthMask((!isTranslucent || enableAlphaDepthWrite) ? GL_TRUE : GL_FALSE);
@ -4321,7 +4320,7 @@ Render3DError OpenGLRenderer_1_2::DrawShadowPolygon(const GLenum polyPrimitive,
}
// Reset the OpenGL states back to their original shadow polygon states.
glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);
glStencilOp(GL_ZERO, GL_KEEP, GL_KEEP);
glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);
glDepthMask(GL_FALSE);
@ -4333,8 +4332,8 @@ Render3DError OpenGLRenderer_1_2::DrawShadowPolygon(const GLenum polyPrimitive,
glDrawElements(polyPrimitive, vertIndexCount, GL_UNSIGNED_SHORT, indexBufferPtr);
}
glStencilFunc(GL_NOTEQUAL, 0x80 | opaquePolyID, 0x3F);
glStencilMask(0x80);
glStencilFunc(GL_NOTEQUAL, opaquePolyID, 0x3F);
glStencilMask(0x40);
return OGLERROR_NOERR;
}

21
desmume/src/OGLRender_3_2.cpp
View File

@ -1887,20 +1887,19 @@ Render3DError OpenGLRenderer_3_2::SetupPolygon(const POLY &thePoly, bool treatAs
// how this 4-pass process works in OpenGL.
if (thePoly.attribute.PolygonID == 0)
{
// 1st pass: Mark stencil buffer bits (0x40) with the shadow polygon volume.
// Bits are only marked on depth-fail.
glStencilFunc(GL_ALWAYS, 0x40, 0xC0);
// 1st pass: Use stencil buffer bit 6 (0x40) for the shadow volume mask.
// Write only on depth-fail.
glStencilFunc(GL_ALWAYS, 0x40, 0x40);
glStencilOp(GL_KEEP, GL_REPLACE, GL_KEEP);
glStencilMask(0xC0);
glStencilMask(0x40);
}
else
{
// 2nd pass: Mark stencil buffer bits (0x80) with the result of the polygon ID
// check. Bits are marked if the polygon ID of this polygon differs from the
// one in the stencil buffer.
glStencilFunc(GL_NOTEQUAL, 0x80 | thePoly.attribute.PolygonID, 0x3F);
glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);
glStencilMask(0x80);
// 2nd pass: Compare stencil buffer bits 0-5 (0x3F) with this polygon's ID. If this stencil
// test fails, remove the fragment from the shadow volume mask by clearing bit 6.
glStencilFunc(GL_NOTEQUAL, thePoly.attribute.PolygonID, 0x3F);
glStencilOp(GL_ZERO, GL_KEEP, GL_KEEP);
glStencilMask(0x40);
}
glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);
@ -1910,7 +1909,7 @@ Render3DError OpenGLRenderer_3_2::SetupPolygon(const POLY &thePoly, bool treatAs
{
glStencilFunc(GL_ALWAYS, thePoly.attribute.PolygonID, 0x3F);
glStencilOp(GL_KEEP, GL_KEEP, (treatAsTranslucent) ? GL_KEEP : GL_REPLACE);
glStencilMask(0xFF); // Drawing non-shadow polygons will implicitly reset the stencil buffer bits
glStencilMask(0x7F); // Drawing non-shadow polygons will implicitly reset the shadow volume mask.
glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
glDepthMask((!treatAsTranslucent || thePoly.attribute.TranslucentDepthWrite_Enable) ? GL_TRUE : GL_FALSE);