void OBBRayPicking::screenPosToWorldRay(
int mouseX, int mouseY, // Mouse position, in pixels, from bottom-left corner of the window
int screenWidth, int screenHeight, // Window size, in pixels
const glm::mat4 &ViewMatrix, // Camera position and orientation
const glm::mat4 &ProjectionMatrix, // Camera parameters (ratio, field of view, near and far planes)
glm::vec3 &out_origin, // Ouput : Origin of the ray. /!\ Starts at the near plane, so if you want the ray to start at the camera's position instead, ignore this.
glm::vec3 &out_direction // Ouput : Direction, in world space, of the ray that goes "through" the mouse.
)
{
// The ray Start and End positions, in Normalized Device Coordinates
glm::vec4 lRayStart_NDC(
((float)mouseX / (float)screenWidth - 0.5f) * 2.0f, // [0,1024] -> [-1,1]
((float)mouseY / (float)screenHeight - 0.5f) * 2.0f, // [0, 768] -> [-1,1]
-1.0, // The near plane maps to Z=-1 in Normalized Device Coordinates
1.0f
);
glm::vec4 lRayEnd_NDC(
((float)mouseX / (float)screenWidth - 0.5f) * 2.0f,
((float)mouseY / (float)screenHeight - 0.5f) * 2.0f,
0.0,
1.0f
);
// The Projection matrix goes from Camera Space to NDC.
// So inverse(ProjectionMatrix) goes from NDC to Camera Space.
glm::mat4 InverseProjectionMatrix = glm::inverse(ProjectionMatrix);
// The View Matrix goes from World Space to Camera Space.
// So inverse(ViewMatrix) goes from Camera Space to World Space.
glm::mat4 InverseViewMatrix = glm::inverse(ViewMatrix);
glm::vec4 lRayStart_camera = InverseProjectionMatrix * lRayStart_NDC; lRayStart_camera /= lRayStart_camera.w;
glm::vec4 lRayStart_world = InverseViewMatrix * lRayStart_camera; lRayStart_world /= lRayStart_world.w;
glm::vec4 lRayEnd_camera = InverseProjectionMatrix * lRayEnd_NDC; lRayEnd_camera /= lRayEnd_camera.w;
glm::vec4 lRayEnd_world = InverseViewMatrix * lRayEnd_camera; lRayEnd_world /= lRayEnd_world.w;
// Faster way (just one inverse)
//glm::mat4 M = glm::inverse(ProjectionMatrix * ViewMatrix);
//glm::vec4 lRayStart_world = M * lRayStart_NDC; lRayStart_world/=lRayStart_world.w;
//glm::vec4 lRayEnd_world = M * lRayEnd_NDC ; lRayEnd_world /=lRayEnd_world.w;
glm::vec3 lRayDir_world(lRayEnd_world - lRayStart_world);
lRayDir_world = glm::normalize(lRayDir_world);
out_origin = glm::vec3(lRayStart_world);
out_direction = glm::normalize(lRayDir_world);
}
void screenPosToWorldRay(
int mouseX,
int mouseY,
int screenWidth,
int screenHeight,
const glm::mat4 &viewMatrix,
const glm::mat4 &projectionMatrix,
glm::vec3& out_origin,
glm::vec3& out_direction)
{
glm::vec4 lRayStart_NDC(
((float)mouseX/(float)screenWidth - 0.5f) * 2.0f,
((float)mouseY/(float)screenHeight - 0.5f) * 2.0f,
-1.0,
1.0f
);
glm::vec4 lRayEnd_NDC(
((float)mouseX/(float)screenWidth - 0.5f) * 2.0f,
((float)mouseY/(float)screenHeight - 0.5f) * 2.0f,
0.0,
1.0f
);
glm::mat4 InverseProjectionMatrix = glm::inverse(projectionMatrix);
glm::mat4 InverseViewMatrix = glm::inverse(viewMatrix);
glm::vec4 lRayStart_camera = InverseProjectionMatrix * lRayStart_NDC; lRayStart_camera/=lRayStart_camera.w;
glm::vec4 lRayStart_world = InverseViewMatrix * lRayStart_camera; lRayStart_world /=lRayStart_world.w;
glm::vec4 lRayEnd_camera = InverseProjectionMatrix * lRayEnd_NDC; lRayEnd_camera /=lRayEnd_camera.w;
glm::vec4 lRayEnd_world = InverseViewMatrix * lRayEnd_camera; lRayEnd_world /=lRayEnd_world.w;
glm::vec3 lRayDir_world(lRayEnd_world - lRayStart_world);
lRayDir_world = glm::normalize(lRayDir_world);
out_origin = glm::vec3(lRayStart_world);
out_direction = glm::normalize(lRayDir_world);
}
