fix: rework cube.cpp file

res/render/primitives/p_cube.frag

@@ -0,0 +1,31 @@
+#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;
+}