glm_vec4_round

[gottfriedleibniz]

glm_vec4_round without SSE41 (e.g., -DGLM_FORCE_SSE2 -DGLM_FORCE_DEFAULT_ALIGNED_GENTYPES) does not properly handle values outside of +/-2^23 (i.e., no fractional part in the float).

For example:

#include <glm/glm.hpp>
#include <glm/gtx/string_cast.hpp>
#include <iostream>

int main(void) {
    glm::vec4 v(8388609.f, 8428605.f, 9988605.f, 10388605.f);
    std::cout << "Expected: " << glm::to_string(v) << std::endl;
    std::cout << "Actual:   " << glm::to_string(glm::floor(v)) << std::endl;
    return 0;
}

// └> g++ -O3 -march=native -I${GLM_PATH} -DGLM_FORCE_SSE2 -DGLM_FORCE_DEFAULT_ALIGNED_GENTYPES round.cpp
// └> ./a.out
// Expected: vec4(8388609.000000, 8428605.000000, 9988605.000000, 10388605.000000)
// Actual:   vec4(8388608.000000, 8428604.000000, 9988604.000000, 10388604.000000)

// └> g++ -O3 -march=native -I${GLM_PATH} -DGLM_FORCE_AVX2 -DGLM_FORCE_DEFAULT_ALIGNED_GENTYPES round.cpp
// └> ./a.out
// Expected: vec4(8388609.000000, 8428605.000000, 9988605.000000, 10388605.000000)
// Actual:   vec4(8388609.000000, 8428605.000000, 9988605.000000, 10388605.000000)