lg_light.c File Reference

Functions
LG_Light	lg_light (lg_light_type type, vec3_t pos_or_dir, LG_Color_f color)
void	lg_set_light_src (LG_Light *light, vec3_t pos)
vec3_t	lg_get_light_src (LG_Light *light)
void	lg_move_light_src (LG_Light *light, vec3_t delta)
void	lg_set_light_dir (LG_Light *light, vec3_t dir)
vec3_t	lg_get_light_dir (LG_Light *light)
void	lg_change_light_dir (LG_Light *light, LG_EulerAng angle, const char *rot_order)

Detailed Description

=== It's all about scene lights position, direction, color ===

Use an array of LG_Light structs if you want to have several different lights in a scene

Lighting is actually a bit complicated:

• Ambiant lighting -> small constant color
• Diffuse lighting ->
  • Directional lighting, using surface normal
    • vec3_t as an orientation
    • Lambert cosine law
  • Point lighting, using surface normal AND distance
    • vec3_t as a position
    • dist = len(light pos - obj pos)
    • attenuation = 1.0 / (light K + light linear K * dist + light quadratic K * pow2(dist))
• Specular lighting ->
  • ...
• Spot lighting
• Combined -> Gouraud / Phong / Blinn-Phong shading
• Gamma correction

(From https://learnopengl.com/Lighting/Materials)
 
uniform Material material;
 
#version 330 core
struct Material {
   vec3 ambient;
   vec3 diffuse;
   vec3 specular;
   float shininess;
};
 
void main()
{
   // ambient
   vec3 ambient = lightColor * material.ambient;
 
   // diffuse
   vec3 norm = normalize(Normal);
   vec3 lightDir = normalize(lightPos - FragPos);
   float diff = max(dot(norm, lightDir), 0.0);
   vec3 diffuse = lightColor * (diff * material.diffuse);
 
   // specular
   vec3 viewDir = normalize(viewPos - FragPos);
   vec3 reflectDir = reflect(-lightDir, norm);
   float spec = pow(max(dot(viewDir, reflectDir), 0.0), material.shininess);
   vec3 specular = lightColor * (spec * material.specular);
 
   vec3 result = ambient + diffuse + specular;
   FragColor = vec4(result, 1.0);
}
 
uniform Light light;
 
struct Light {
   vec3 position;
 
   vec3 ambient;
   vec3 diffuse;
   vec3 specular;
};
 
Lighting maps
   ...
Specular maps
   ...

TODO

• Should LG_Light pos and dir be in a union or not ?
• Complete this

Function Documentation

lg_light()

LG_Light lg_light	(	lg_light_type	type,
		vec3_t	pos_or_dir,
		LG_Color_f	color
	)

Return a new LG_Light

Parameters

type	Light type (lg_light_type enum), one of POINT, DIRECTIONAL, SPOTLIGHT, AMBIENT, DIFFUSE, EMISSIVE, SPECULAR
pos_or_dir	Source of light (vec3_t) in case of POINT light or light orientation (vec3_t) in case of DIRECTIONAL light
color	Light color

Returns

A new LG_Light

lg_set_light_src()

void lg_set_light_src	(	LG_Light *	light,
		vec3_t	pos
	)

Set light source position

Parameters

light	A LG_Light
pos	Light source pos

lg_get_light_src()

vec3_t lg_get_light_src

(

LG_Light *

light

)

Read light source position

Parameters

light

A LG_Light

Returns

Light source pos

lg_move_light_src()

void lg_move_light_src	(	LG_Light *	light,
		vec3_t	delta
	)

Move light source position by delta

Parameters

light	A LG_Light
delta	Translation vector

lg_set_light_dir()

void lg_set_light_dir	(	LG_Light *	light,
		vec3_t	dir
	)

Set light orientation

Parameters

light	A LG_Light
dir	Light dir

lg_get_light_dir()

vec3_t lg_get_light_dir

(

LG_Light *

light

)

Read light orientation

Parameters

light

A LG_Light

Returns

Light dir

lg_change_light_dir()

void lg_change_light_dir	(	LG_Light *	light,
		LG_EulerAng	angle,
		const char *	rot_order
	)

Change light orientation by rotating by Euler angle

Parameters

light	A LG_Light
rot	Rotation to apply (Euler angle)
rot_order	Rotation order, one of "XYZ", "YXZ", "ZXY", "ZYX", "YZX", "XZY"