lighting – Why are the walls so different in a Webgl scene?

I'm trying to render a piece (composed of 2 shots) in webgl with the library of regl. I'm using a shader with a point source of light and the rendered scene is pretty good, but I see a lot of difference between the horizontal and vertical planes: the horizontal has a bright spot that disappears slightly in the l & # 39; darkness while the vertical plane seems to have a much wider place.

Why this difference? What am I doing wrong?

Here is the rendering of the piece with an orange sphere in position of light:

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and here is the top and fragment of the piece:

green const = `
float mediump precision;

assigns the position vec3;
attribute vec3 normal;

uniform mat4 projection;
uniform view mat4;
uniform mat4 model;

variant vec3 vModelPosition;
variant vec3 vNormal;

void main () {
mat4 modelViewMatrix = view * model;
vec4 viewModelPosition = modelViewMatrix * vec4 (position, 1.0);
gl_Position = projection * viewModelPosition;

vModelPosition = (model * vec4 (position, 1.0)). X Y Z;
vNormal = normal;

const frag = `
float mediump precision;

uniform vec3 diffuseColor;
uniform vec3 ambientColor;
uniform vec3 lightPosition;
uniform samplerCube shadowCube;

variant vec3 vModelPosition;
variant vec3 vNormal;

void main () {
vec3 lightDirection = normalize (lightPosition - vModelPosition);
vec3 normal = normalize (vNormal);
Float brightness = max (
), 0,0);

vec3 lightColor = max ((diffuseColor * bright), ambientColor);

gl_FragColor = vec4 (lightColor, 1.0);