;;;; basic-shaders.lisp (Lisp shader code)
(in-package wh-engine/render)

(define-shader basic-shader
    (:in ((vert-pos :type :vec3 :location 0)
          (vert-uv :type :vec2 :location 1))
     :out ((*frag-colour* :type :vec4))
     :uniform ((model :type :mat4)
               (view :type :mat4)
               (proj :type :mat4)
               (main-tex :type :sampler-2d)
               (colour :type :vec4)))
  :documentation "Simple shader for 2D sprites."
  :version 330
  :vert ((setf *position* (* proj view model (vec4 vert-pos 1.0))))
  :frag ((setf *frag-colour* (* (sample-texture main-tex vert-uv) colour)))
  :options (:depth-test t
            :depth-write t
            :blend t))

(define-shader render-target-blit-shader
    (:in ((vert-pos :type :vec2 :location 0))
     :out ((*frag-colour* :type :vec4)
           (*frag-depth* :type :float))
     :uniform ((main-tex :type :sampler-2d)
               (depth-tex :type :depth-sampler-2d)))
  :documentation "Shader for compositing render targets together."
  :version 330
  :vert ((setf *position* (vec4 vert-pos 0.0 1.0)))
  :frag ((setf *frag-colour* (sample-texture main-tex vert-pos)
               *frag-depth* (sample-texture depth-tex vert-pos)))
  :options (:depth-test t
            :depth-write t
            :blend nil))

(define-shader ui-basic-shader
    (:in ((vert-pos :type :vec2 :location 0)
          (vert-uv :type :vec2 :location 1))
     :out ((*frag-colour* :type :vec4))
     :uniform ((model :type :mat4)
               (proj :type :mat4)
               (main-tex :type :sampler-2d)
               (colour :type :vec4)))
  :documentation "Simple shader for overlay UI."
  :version 330
  :vert ((setf *position* (* proj model (vec4 vert-pos 1.0 1.0))))
  :frag ((setf *frag-colour* (* (sample-texture main-tex vert-uv) colour)))
  :options (:depth-test nil
            :depth-write nil
            :blend t))

(define-shader ui-glyph-shader
    (:in ((vert-pos :type :vec2 :location 0)
          (vert-uv :type :vec2 :location 1))
     :out ((*frag-colour* :type :vec4))
     :uniform ((model :type :mat4)
               (proj :type :mat4)
               (main-tex :type :sampler-2d)
               (colour :type :vec3)))
  :documentation "Shader for text and other glyphs within overlay UI."
  :version 330
  :vert ((setf *position* (* proj model (vec4 vert-pos 1.0 1.0))))
  :frag ((setf *frag-colour* (vec4 colour (vx (sample-texture main-tex vert-uv)))))
  :options (:depth-test nil
            :depth-write nil
            :blend t))