feat: replace triangle test by cube

res/render/primitives/p_cube.frag

@@ -1,31 +1,11 @@
 #version 330 core
 out vec4 FragColor;
 
-struct Material
-{
-  sampler2D diffuse;
-  vec3 specular;
-  float shininess;
-};
-struct Light
-{
-  vec3 position;
-
-  vec3 ambient;
-  vec3 diffuse;
-  vec3 specular;
-};
-
 in vec3 FragPos;
 in vec3 Normal;
 in vec2 TexCoords;
 
-uniform vec3 viewPos;
-uniform Material material;
-uniform Light light;
-
 void main()
 {
-  vec4 texColor = texture(material.diffuse , TexCoords);
-  FragColor = texColor;
+  FragColor = vec4(0.8, 0.8, 1.0, 1.0);
 }