Listening to mouse input
GLFW documentation on Mouse Input
Java and Kotlin don’t support pointers, so you need to create a buffer to read the mouse position (StackOverflow post)
val positionX = BufferUtils.createDoubleBuffer(1)
val positionY = BufferUtils.createDoubleBuffer(1)
glfwGetCursorPos(window, positionX, positionY)Mouse Picking with Ray Casting
Article by Anton Gerdelan on Mouse Picking with Ray Casting.
Tutorial on Model-View-Projection matrices in OpenGL
As a reference, code I wrote many years ago in C++:
auto Camera::calculateClickRay(int x, int y, glm::vec3& point, glm::vec3& direction) -> void {
// Y coord is inverted in OpenGL
int transformedY = m_windowHeight - y;
// Transform coordinates to world space
glm::vec3 nearPoint = glm::unProject(glm::vec3(x, transformedY, 0.0f),
m_viewMatrix,
m_projectionMatrix,
glm::vec4(0.0, 0.0, m_windowWidth, m_windowHeight));
// Transform coordinates of far off point to calculate direction
glm::vec3 farPoint = glm::unProject(glm::vec3(x, transformedY, 1.0f),
m_viewMatrix,
m_projectionMatrix,
glm::vec4(0.0, 0.0, m_windowWidth, m_windowHeight));
point = nearPoint;
direction = farPoint - nearPoint;
}JOML has unprojectRay (documentation)