feat(render): basic normal-based lighting

shaders/shader.frag

@@ -1,10 +1,19 @@
 #version 450
 
 layout(location = 0) in vec2 tex_coords;
+layout(location = 1) in vec3 normal;
 layout(set = 1, binding = 0) uniform texture2D t_diffuse;
 layout(set = 1, binding = 1) uniform sampler s_diffuse;
 layout(location = 0) out vec4 out_color;
 // layout(group = 0, binding = 0) out texture2D;
 void main() {
+    float ambient = 0.2;
+    vec3 light_dir = normalize(vec3(0.5, 1.0, 0.5));
+    float diffuse = clamp(dot(normalize(normal), light_dir), 0.0, 1.0);
+    float brightness = ambient + (1.0 - ambient) * diffuse;
+
     out_color = texture(sampler2D(t_diffuse, s_diffuse), tex_coords);
+    out_color.r = clamp(out_color.r * 0.6 * brightness, 0.0, 1.0);
+    out_color.g = clamp(out_color.g * 0.6 * brightness, 0.0, 1.0);
+    out_color.b = clamp(out_color.b * 0.9 * brightness, 0.0, 1.0);
 }

shaders/shader.vert

@@ -2,14 +2,17 @@
 
 layout(location = 0) in vec3 position;
 layout(location = 1) in vec3 color;
+layout(location = 2) in vec3 normal_in;
 layout(location = 3) in vec2 tex_coords;
 layout(location = 0) out vec2 tex_coord;
+layout(location = 1) out vec3 normal;
 layout(set = 0, binding = 0) uniform UniformBufferObject {
     mat4x4 projection;
 } view;
 void main() {
     gl_Position = view.projection * vec4(position, 1.0);
     tex_coord = tex_coords;
+    normal = normal_in;
     // gl_Position
     // out_color = color;
 }