feat(rendering): add basic diffuse and ambient lighting to block rendering

assets/shaders/block_f_shader.glsl

@@ -1,15 +1,35 @@
 #version 460
 
 in vec2 tc;
+in vec3 normal;
+in vec3 vert_pos;
 flat in int tex_layer;
 out vec4 color;
 
 layout (binding = 0) uniform sampler2DArray samp;
 
+uniform float ambientStrength;
+uniform vec3 sunlightColor;
+uniform vec3 sunlightDir;
+
 void main(void) {
-    color = texture(samp, vec3(tc, tex_layer));
-    if (color.a < 0.8) {
+    vec4 objectColor = texture(samp, vec3(tc, tex_layer));
+    
+    if (objectColor.a < 0.8) {
         discard;
     }
+
+    vec3 lightDir = normalize(sunlightDir);
+    
+    vec3 ambient = ambientStrength * sunlightColor;
+    
+    vec3 norm = normalize(normal);
+    
+    float diff = max(dot(norm, lightDir), 0.0);
+    
+    vec3 diffuse = diff * sunlightColor;
+    
+    color = vec4((ambient + diffuse) * objectColor.rgb, objectColor.a);
+
     //color = varyingColor;
 }