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[Fix] (Review): convert every scalar sampler query to the type the caller asked for instead of the other type's bit pattern

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swung0x48
2026-08-27 08:35:04 -04:00
parent d9aebcba26
commit 1f44e5bc1d
1 changed files with 65 additions and 19 deletions
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MobileGL/MG_Impl/GLImpl/Sampler/GL_Sampler.cpp
+65 -19
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@@ -30,6 +30,43 @@ namespace MobileGL::MG_Impl::GLImpl {
return pname == GL_TEXTURE_BORDER_COLOR;
}
// A state query returns the value CONVERTED to the type the caller asked for (GL 4.6 core
// 2.2.2 / 6.1), never the other type's bits. These two are the sampler side of the numeric
// casts GetTexParameterfv_State/GetTexParameteriv_State already do on the texture side; the
// sampler path funnels all three spellings through one void* function, which is precisely how
// it came to write a fixed type regardless of the caller.
//
// Truncation rather than rounding for the float -> integer direction, matching the texture
// twin (GetTexParameteriv_State's static_cast<GLint> on MIN_LOD/MAX_LOD/LOD_BIAS): the two
// spellings of the same state disagreeing is the bug being fixed here, and a texture and a
// sampler queried the same way must answer the same number.
void StoreSamplerScalar(void* params, Bool isFloat, Bool isUnsignedInteger, Float value) {
if (isFloat) {
*(GLfloat*)params = value;
return;
}
// Via GLint in both integer spellings: a direct float -> GLuint cast of a negative value
// (GL_TEXTURE_MIN_LOD defaults to -1000) is undefined behaviour, while the two-step
// conversion is the well-defined modular one, and it is what the texture-side
// GetTexParameterIuiv fallback does.
const GLint asInt = static_cast<GLint>(value);
if (isUnsignedInteger) {
*(GLuint*)params = static_cast<GLuint>(asInt);
} else {
*(GLint*)params = asInt;
}
}
void StoreSamplerEnum(void* params, Bool isFloat, Bool isUnsignedInteger, GLenum value) {
if (isFloat) {
*(GLfloat*)params = static_cast<GLfloat>(value);
} else if (isUnsignedInteger) {
*(GLuint*)params = value;
} else {
*(GLint*)params = static_cast<GLint>(value);
}
}
Bool ValidateSamplerParameterValue(GLenum pname, const void* param, Bool isFloat, Bool isUnsignedInteger) {
if (param == nullptr) return false;
@@ -163,47 +200,56 @@ namespace MobileGL::MG_Impl::GLImpl {
if (!SamplerImpl::ValidateSamplerObject(sampler)) return;
using namespace MG_Util;
// Every scalar pname goes through StoreSamplerScalar/StoreSamplerEnum so the CALLER'S form
// decides the destination type. Writing a fixed type regardless - which is what these case
// labels used to do - hands back the other type's bit pattern rather than a converted value:
// glGetSamplerParameterfv(GL_TEXTURE_WRAP_S) deposited the integer 10497 into a GLfloat and
// the caller read 1.47e-41, and glGetSamplerParameteriv(GL_TEXTURE_MIN_LOD) deposited the
// IEEE bits of -1000.0f and the caller read -998637568. Sixteen (pname, entry-point) pairs
// were broken this way; only MAX_ANISOTROPY_EXT and BORDER_COLOR branched correctly, which is
// how the same bug class was already found and fixed once for a single pname.
switch (pname) {
case GL_TEXTURE_WRAP_S:
*(GLuint*)params = MG_Util::ConvertSamplerWrapModeToGLEnum(samplerObj->GetWrapS());
StoreSamplerEnum(params, isFloat, isUnsignedInteger,
MG_Util::ConvertSamplerWrapModeToGLEnum(samplerObj->GetWrapS()));
break;
case GL_TEXTURE_WRAP_T:
*(GLuint*)params = MG_Util::ConvertSamplerWrapModeToGLEnum(samplerObj->GetWrapT());
StoreSamplerEnum(params, isFloat, isUnsignedInteger,
MG_Util::ConvertSamplerWrapModeToGLEnum(samplerObj->GetWrapT()));
break;
case GL_TEXTURE_WRAP_R:
*(GLuint*)params = MG_Util::ConvertSamplerWrapModeToGLEnum(samplerObj->GetWrapR());
StoreSamplerEnum(params, isFloat, isUnsignedInteger,
MG_Util::ConvertSamplerWrapModeToGLEnum(samplerObj->GetWrapR()));
break;
case GL_TEXTURE_MIN_FILTER:
*(GLuint*)params =
MG_Util::ConvertSamplerFilterModeToGLEnum(samplerObj->GetMinFilter(), samplerObj->GetMipmapMode());
StoreSamplerEnum(params, isFloat, isUnsignedInteger,
MG_Util::ConvertSamplerFilterModeToGLEnum(samplerObj->GetMinFilter(),
samplerObj->GetMipmapMode()));
break;
case GL_TEXTURE_MAG_FILTER:
*(GLuint*)params =
MG_Util::ConvertSamplerFilterModeToGLEnum(samplerObj->GetMagFilter(), SamplerMipmapMode::None);
StoreSamplerEnum(params, isFloat, isUnsignedInteger,
MG_Util::ConvertSamplerFilterModeToGLEnum(samplerObj->GetMagFilter(),
SamplerMipmapMode::None));
break;
case GL_TEXTURE_MIN_LOD:
*(GLfloat*)params = samplerObj->GetMinLod();
StoreSamplerScalar(params, isFloat, isUnsignedInteger, samplerObj->GetMinLod());
break;
case GL_TEXTURE_MAX_LOD:
*(GLfloat*)params = samplerObj->GetMaxLod();
StoreSamplerScalar(params, isFloat, isUnsignedInteger, samplerObj->GetMaxLod());
break;
case GL_TEXTURE_LOD_BIAS:
*(GLfloat*)params = samplerObj->GetLodBias();
StoreSamplerScalar(params, isFloat, isUnsignedInteger, samplerObj->GetLodBias());
break;
case GL_TEXTURE_MAX_ANISOTROPY_EXT:
if (isFloat) {
*(GLfloat*)params = samplerObj->GetMaxAnisotropy();
} else if (isUnsignedInteger) {
*(GLuint*)params = static_cast<GLuint>(samplerObj->GetMaxAnisotropy());
} else {
*(GLint*)params = static_cast<GLint>(samplerObj->GetMaxAnisotropy());
}
StoreSamplerScalar(params, isFloat, isUnsignedInteger, samplerObj->GetMaxAnisotropy());
break;
case GL_TEXTURE_COMPARE_MODE:
*(GLuint*)params = MG_Util::ConvertSamplerCompareModeToGLEnum(samplerObj->GetCompareMode());
StoreSamplerEnum(params, isFloat, isUnsignedInteger,
MG_Util::ConvertSamplerCompareModeToGLEnum(samplerObj->GetCompareMode()));
break;
case GL_TEXTURE_COMPARE_FUNC:
*(GLuint*)params = MG_Util::ConvertSamplerCompareFuncToGLEnum(samplerObj->GetSamplerCompareFunc());
StoreSamplerEnum(params, isFloat, isUnsignedInteger,
MG_Util::ConvertSamplerCompareFuncToGLEnum(samplerObj->GetSamplerCompareFunc()));
break;
case GL_TEXTURE_BORDER_COLOR: {
if (isFloat) {