The "Light" input of the ExpressionME-L Node, when used with the Light condition helper Node, allows for the evaluation of lights and illumination based on positions in 3D space. This can be useful for using lights to steer or control effects by determining the intensity of illumination at specific points.
Global Variables
| Variable | Description |
|---|---|
| lights_in_count | The number of lights in the list. |
| lights_in_id | returns the index of the input you created (starting with 0 excluding Time and On). |
Used to evaluate lights in a scene, this function does not support shadows (only a renderer can do that), but does support projection maps.
Calls:
lights_in_illum(in_light_id, in_position[3], out_color)
lights_in_illum(in_light_id, in_position[3], out_color, in_normal[3])
lights_in_illum(in_light_id, in_position[3], out_color, in_normal[3], in_side)
Parameters:
| Parameter | Description |
|---|---|
| in_light_id | The id of the light to evaluate, or a value less than 0 to evaluate all lights. |
| in_position | A world space position to illuminate. |
| out_color | The color from the light. |
| in_normal | The surface normal. |
| in_side | Which normal side to use. A value greater than 0 for the front side, 0 for both front and back, and less than 0 for only the backside. |
Return:
| Return value | Description |
|---|---|
| 0 | Fail. |
| < 0 | Backside. |
| > 0 | Frontside. |
This function is only valid when a previous lights_in_illum call has been succcessful. This function returns specific information regrading illumination data of the lights.
Calls:
lights_in_illum_result(in_illum_data, out_scalar)
lights_in_illum_result(in_illum_data, out_vector)
Parameters:
| Parameter | Description |
|---|---|
| in_illum_data | Selects the data to retrive from the illumination result |
| out_scalar | stores the scalar data form the illumination result |
| out_vector | Stores the information form the illumination result |
Light Illum Data:
| Parameter | Description |
|---|---|
| lights_illum_pos | Returns the position of the illuminated point (world position) |
| lights_illum_norm | Returns the normal of the illuminated point (world normal) |
| lights_illum_dir | Returns the direction towards the light as seen from the illuminated point (world normal) |
| lights_illum_dot | Returns the dot product of the normal and the direction (the angle between normal and light) |
| lights_illum_col | Returns the color of the illuminated point |
Return:
| Return value | Description |
|---|---|
| 0 | Fail. |
| 1 | Succeed |
Used to gather information about lights connected to the ME-LExpression Node through a light condition Node.
Calls:
lights_in_info(in_light_id, in_lights_info, out_vector)
lights_in_info(in_light_id, in_lights_info, out_scalar)
Parameters:
| Parameter | Description |
|---|---|
| in_light_id | The id of the light to evaluate, or a value less than 0 to evaluate all lights. |
| in_lights_info | Defines which information to request from the light |
| out_vector | Stores the infromation (color,position...) |
| out_scalar | Used to store scalar value (mono values or intensity) |
Light Info:
| Parameter | Description |
|---|---|
| lights_info_pos | Gets the world positon of the light (vector) |
| lights_info_dir | Get the light's direction (vector) |
| lights_info_col | Gets the color of the light color (vector for color or scalar for intensity ...) |
Return:
| Return value | Description |
|---|---|
| 0 | Fail. |
| 1 | Succeed |