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Handle case where an implementation can't readback 'native' format/type

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* Sometimes a GLES implementation can refuse to copy back the 'native'
  format/type, most commonly if you want to read back from a GL_RGB texture it
  might require you to readback GL_RGBA.
* We handle this by just reading back the requested format in this case, and
  then copying only RGB tightly into the output buffer.
This commit is contained in:
baldurk
2018-07-09 16:27:57 +01:00
parent f2a2710823
commit eff35de81b
1 changed files with 70 additions and 1 deletions
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renderdoc/driver/gl/wrappers/gl_emulated.cpp
+70 -1
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@@ -1870,7 +1870,76 @@ void APIENTRY _glGetTexImage(GLenum target, GLint level, GLenum format, GLenum t
byte *dst = (byte *)pixels + d * sliceSize;
GLenum readFormat = fixBGRA ? eGL_RGBA : format;
GL.glReadPixels(0, 0, width, height, readFormat, type, (void *)dst);
GLenum implFormat = eGL_NONE, implType = eGL_NONE;
GL.glGetIntegerv(eGL_IMPLEMENTATION_COLOR_READ_FORMAT, (GLint *)&implFormat);
GL.glGetIntegerv(eGL_IMPLEMENTATION_COLOR_READ_TYPE, (GLint *)&implType);
// spec says this must be supported
bool validReadback = (readFormat == eGL_RGBA && type == eGL_UNSIGNED_BYTE);
// the implementation is allowed to support one other format/type pair, it can vary by texture.
// Normally this will be the 'natural' readback format/type pair that we are trying
validReadback |= (readFormat == implFormat && type == implType);
if(validReadback)
{
GL.glReadPixels(0, 0, width, height, readFormat, type, (void *)dst);
}
else
{
// unfortunately the readback is not supported directly, we'll need to fudge it.
RDCDEBUG("Reading as %s/%s but impl supported pair is %s/%s", ToStr(readFormat).c_str(),
ToStr(type).c_str(), ToStr(implFormat).c_str(), ToStr(implType).c_str());
if(readFormat == implFormat && (type == eGL_HALF_FLOAT_OES || type == eGL_HALF_FLOAT) &&
(implType == eGL_HALF_FLOAT_OES || implType == eGL_HALF_FLOAT))
{
// if the format itself is supported and we just have a mismatch between eGL_HALF_FLOAT_OES
// and eGL_HALF_FLOAT (different enum values), we can just use the implementation's pair
// as-is.
GL.glReadPixels(0, 0, width, height, readFormat, implType, (void *)dst);
}
else if(readFormat == eGL_RGB && implFormat == eGL_RGBA && type == implType)
{
// if the only difference is that the implementation wants to read RGBA for an RGB format
// (could be understandable if the native storage is RGBA anyway for RGB textures) then we
// can readback into a temporary buffer and strip the alpha.
size_t size = GetByteSize(width, height, 1, implFormat, type);
byte *readback = new byte[size];
GL.glReadPixels(0, 0, width, height, implFormat, implType, readback);
// how big is a component (1/2/4 bytes)
size_t compSize = GetByteSize(1, 1, 1, eGL_RED, type);
byte *src = readback;
// for each pixel
for(GLint i = 0; i < width * height; i++)
{
// copy RGB
memcpy(dst, src, compSize * 3);
// advance dst by RGB
dst += compSize * 3;
// advance src by RGBA
src += compSize * 4;
}
delete[] readback;
fixBGRA = false;
}
else
{
RDCERR("Unhandled readback failure");
memset(dst, 0, sliceSize);
}
}
if(fixBGRA)
{