#version 450
#extension GL_ARB_separate_shader_objects : enable

struct Object {
   mat4 model;
   float hp;
   bool deleted;
};

layout (binding = 0) uniform UniformBufferObject {
   mat4 view;
   mat4 proj;
} ubo;

layout(binding = 1) readonly buffer StorageBufferObject {
   Object objects[];
} sbo;

layout(location = 0) in vec3 vertex_position;
layout(location = 1) in vec3 vertex_color;
layout(location = 2) in vec3 vertex_normal;
layout(location = 3) in uint obj_index;

layout(location = 0) out vec3 position_eye;
layout(location = 1) out vec3 color;
layout(location = 2) out vec3 normal_eye;
layout(location = 3) out vec3 light_position_eye;
layout(location = 4) out vec3 light2_position_eye;

// fixed point light position
vec3 light_position_world = vec3(0.0, 0.0, 2.0);
vec3 light2_position_world = vec3(0.0, 1.5, -0.1);

void main() {
   position_eye = vec3(ubo.view * sbo.objects[obj_index].model * vec4(vertex_position, 1.0));
   normal_eye = normalize(vec3(ubo.view * sbo.objects[obj_index].model * vec4(vertex_normal, 0.0)));

   float hp_percent = sbo.objects[obj_index].hp / 10.0;
   vec3 damage_color = vec3(1.0, 0.0, 0.0);
   color = (vertex_color * hp_percent) + (damage_color * (1.0 - hp_percent));

   light_position_eye = vec3(ubo.view * vec4(light_position_world, 1.0));
   light2_position_eye = vec3(ubo.view * vec4(light2_position_world, 1.0));

   if (sbo.objects[obj_index].deleted) {
      gl_Position = vec4(0.0, 0.0, 2.0, 1.0);
   } else {
      gl_Position = ubo.proj * vec4(position_eye, 1.0);
   }
}