Fixed EXT_matrix_transform inverted shear matrix multiple #1140 #1182

Author: christophe-lunarg

glm/ext/matrix_transform.inl

@@ -117,10 +117,10 @@ namespace glm
         );
 
         mat<4, 4, T, Q> Result;
-        Result[0] = Shear[0] * m[0][0] + Shear[1] * m[0][1] + Shear[2] * m[0][2] + Shear[3] * m[0][3];
-        Result[1] = Shear[0] * m[1][0] + Shear[1] * m[1][1] + Shear[2] * m[1][2] + Shear[3] * m[1][3];
-        Result[2] = Shear[0] * m[2][0] + Shear[1] * m[2][1] + Shear[2] * m[2][2] + Shear[3] * m[2][3];
-        Result[3] = Shear[0] * m[3][0] + Shear[1] * m[3][1] + Shear[2] * m[3][2] + Shear[3] * m[3][3];
+		Result[0] = m[0] * Shear[0][0] + m[1] * Shear[0][1] + m[2] * Shear[0][2] + m[3] * Shear[0][3];
+		Result[1] = m[0] * Shear[1][0] + m[1] * Shear[1][1] + m[2] * Shear[1][2] + m[3] * Shear[1][3];
+		Result[2] = m[0] * Shear[2][0] + m[1] * Shear[2][1] + m[2] * Shear[2][2] + m[3] * Shear[2][3];
+		Result[3] = m[0] * Shear[3][0] + m[1] * Shear[3][1] + m[2] * Shear[3][2] + m[3] * Shear[3][3];
         return Result;
     }
 

readme.md

@@ -114,6 +114,7 @@ target_link_libraries(main PRIVATE glm::glm)
 #### Fixes:
 - Fixed C++ language auto detection build, disable C++98 warnings with Clang #1235, #1231
 - Fixed `GTX_color_space` missing <glm/ext/scalar_constants.hpp> include #1233 #1238
+- Fixed `EXT_matrix_transform` `shear` implementation #1140 #1182
 
 ### [GLM 1.0.0](https://github.com/g-truc/glm/releases/tag/1.0.0) - 2024-01-24
 #### Features:

test/core/core_func_matrix.cpp

@@ -280,12 +280,14 @@ static int test_shearing()
                 glm::vec4(1, 1, 1, 0),
                 glm::vec4(1, 1, 0, 1));
         glm::mat4x4 const B4x4 = glm::shear(A4x4, center, l_x, l_y, l_z);
+        glm::mat4x4 const C4x4 = glm::shear_slow(A4x4, center, l_x, l_y, l_z);
         glm::mat4x4 const expected(
                 glm::vec4(0, 0, 1, 1),
-                glm::vec4(2, 1, 1, 0),
-                glm::vec4(3, 1, 1, 0),
-                glm::vec4(3, 1, 0, 1));
+                glm::vec4(0, 1, 3, 2),
+                glm::vec4(1, 1, 1, 0),
+                glm::vec4(1, 1, 0, 1));
         Error += all(equal(B4x4, expected, epsilon<float>())) ? 0 : 1;
+        Error += all(equal(C4x4, expected, epsilon<float>())) ? 0 : 1;
     }
 
     {
@@ -299,12 +301,14 @@ static int test_shearing()
                 glm::vec4(1, 1, 1, 0),
                 glm::vec4(1, 0, 0, 0));
         glm::mat4x4 const B4x4 = glm::shear(A4x4, center, l_x, l_y, l_z);
+        glm::mat4x4 const C4x4 = glm::shear_slow(A4x4, center, l_x, l_y, l_z);
         glm::mat4x4 const expected(
-                glm::vec4(0, 1, 1, 0),
-                glm::vec4(1, 2, 1, 0),
-                glm::vec4(2, 2, 2, 0),
-                glm::vec4(1, 0, 1, 0));
+                glm::vec4(1, 1, 2, 0),
+                glm::vec4(0, 1, 2, 0),
+                glm::vec4(1, 2, 2, 0),
+                glm::vec4(1, 0, 0, 0));
         Error += all(equal(B4x4, expected, epsilon<float>())) ? 0 : 1;
+        Error += all(equal(C4x4, expected, epsilon<float>())) ? 0 : 1;
     }
 
     {
@@ -314,12 +318,14 @@ static int test_shearing()
         glm::vec2 const l_z(4, 5);
         glm::mat4x4 const A4x4(1);
         glm::mat4x4 const B4x4 = glm::shear(A4x4, center, l_x, l_y, l_z);
+        glm::mat4x4 const C4x4 = glm::shear_slow(A4x4, center, l_x, l_y, l_z);
         glm::mat4x4 const expected(
                 glm::vec4(1, 3, 4, 0),
                 glm::vec4(1, 1, 5, 0),
                 glm::vec4(2, 1, 1, 0),
                 glm::vec4(-9, -8, -9, 1));
         Error += all(equal(B4x4, expected, epsilon<float>())) ? 0 : 1;
+        Error += all(equal(C4x4, expected, epsilon<float>())) ? 0 : 1;
     }
 
     {
@@ -333,12 +339,14 @@ static int test_shearing()
                 glm::vec4(4, -8, 0, 0),
                 glm::vec4(7, 1, -2, 0));
         glm::mat4x4 const B4x4 = glm::shear(A4x4, center, l_x, l_y, l_z);
+        glm::mat4x4 const C4x4 = glm::shear_slow(A4x4, center, l_x, l_y, l_z);
         glm::mat4x4 const expected(
-                glm::vec4(1, -6, -1, 0),
-                glm::vec4(7, 12, 23, 0),
-                glm::vec4(-4, 4, -24, 0),
-                glm::vec4(4, 20, 31, 0));
+                glm::vec4(22, -24, 4, 0),
+                glm::vec4(20, -36, 2, 0),
+                glm::vec4(1, -2, 3, 0),
+                glm::vec4(-26, 39, -19, 0));
         Error += all(equal(B4x4, expected, epsilon<float>())) ? 0 : 1;
+        Error += all(equal(C4x4, expected, epsilon<float>())) ? 0 : 1;
     }
 
     return Error;
@@ -392,19 +400,20 @@ static int test_inverse_perf(std::size_t Count, std::size_t Instance, char const
 int main()
 {
 	int Error = 0;
+
 	Error += test_matrixCompMult();
 	Error += test_outerProduct();
 	Error += test_transpose();
 	Error += test_determinant();
 	Error += test_inverse();
-    Error += test_inverse_simd();
-    Error += test_shearing();
+	Error += test_inverse_simd();
+	Error += test_shearing();
 
-#	ifdef NDEBUG
+#ifdef NDEBUG
 	std::size_t const Samples = 1000;
-#	else
+#else
 	std::size_t const Samples = 1;
-#	endif//NDEBUG
+#endif//NDEBUG
 
 	for(std::size_t i = 0; i < 1; ++i)
 	{