static/local array


Chris Forone


i have some strange behavior in my multithreaded app. i do some
matrix-multiplications in a methode. if i use local arrays there it
works, but if i use a static member array (some kind of reusable array)
it doesnt work anymore. some code snippets:

[matrix multiplication]
template <typename T>
inline void MultiplyMatrix(T(&first)[16], T(&second)[16])
GLfloat result[16];

for (std::size_t i(0); i < 16; i += 4)
for (std::size_t j(0); j < 4; ++j)
result[i + j] = first * second[j]
+ first[i + 1] * second[j + 4]
+ first[i + 2] * second[j + 8]
+ first[i + 3] * second[j + 12];

std::copy(result, result + 16, first);

[here i use matrix multiplication, write to local/static array]
void Object::Draw() const
GLfloat localTempMatrix[] =
1.0f, 0.0f, 0.0f, 0.0f,
0.0f, 1.0f, 0.0f, 0.0f,
0.0f, 0.0f, 1.0f, 0.0f,
0.0f, 0.0f, 0.0f, 1.0f

localTempMatrix[12] = position[Coordinate::X];
localTempMatrix[13] = position[Coordinate::Y];
MultiplyMatrix(localTempMatrix, projectionMatrix);

GLint programId(0);
glGetIntegerv(GL_CURRENT_PROGRAM, &programId);

glUniformMatrix4fv(glGetUniformLocation(programId, "matrix"), 1,
GL_FALSE, localTempMatrix);

thanks a lot!

cheers, chris



Chris Forone

ok, i now use the new std::array<float, 16> and it works perfect. thanks
a lot!

cheers, chris

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