Fix cubemap sampling at (0, 0, 0) division by zero

Whichever direction was chosen as the 'major' one, a division by zero occurred when trying to project to its corresponding face. Prevent it by ensuring 'M' is greater than zero. Bug: b/132981873 Test: dEQP-VK.glsl.opaque_type_indexing.sampler.const_literal.compute.samplercube Change-Id: I71c25be4d8e17409cc9bf32a2f6180db9a948d34 Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/31729 Presubmit-Ready: Nicolas Capens <nicolascapens@google.com> Kokoro-Presubmit: kokoro <noreply+kokoro@google.com> Reviewed-by: Chris Forbes <chrisforbes@google.com> Tested-by: Nicolas Capens <nicolascapens@google.com>

Fix cubemap sampling at (0, 0, 0) division by zero
19a0081c · Nicolas Capens · Nicolas Capens · 8d548b6c · 19a0081c
Commit 19a0081c authored May 17, 2019 by Nicolas Capens Committed by Nicolas Capens May 18, 2019
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SamplerCore.cpp src/Pipeline/SamplerCore.cpp +3 -1

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--- a/src/Pipeline/SamplerCore.cpp
+++ b/src/Pipeline/SamplerCore.cpp
@@ -19,6 +19,8 @@
 #include "Vulkan/VkSampler.hpp"
 #include "Vulkan/VkDebug.hpp"
+#include <limits>
 namespace
 {
 	void applySwizzle(VkComponentSwizzle swizzle, sw::Float4& f, const sw::Vector4f& c, bool integer)
@@ -1126,7 +1128,7 @@ namespace sw
 		face[3] = (face[0] >> 12) & 0x7;
 		face[0] &= 0x7;
-		M = Max(Max(absX, absY), absZ);
+		M = Max(Max(absX, absY), Max(absZ, Float4(std::numeric_limits<float>::min())));
 		// U = xMajor ? (neg ^ -z) : ((zMajor & neg) ^ x)
 		U = As<Float4>((xMajor & (n ^ As<Int4>(-z))) | (~xMajor & ((zMajor & n) ^ As<Int4>(x))));