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;;; Chickadee Game Toolkit
;;; Copyright © 2019, 2021 David Thompson <davet@gnu.org>
;;;
;;; Chickadee is free software: you can redistribute it and/or modify
;;; it under the terms of the GNU General Public License as published
;;; by the Free Software Foundation, either version 3 of the License,
;;; or (at your option) any later version.
;;;
;;; Chickadee is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;;; General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with this program. If not, see
;;; <http://www.gnu.org/licenses/>.
;;; Commentary:
;;
;; Physically based lighting model.
;;
;;; Code:
(define-module (chickadee graphics pbr)
#:use-module (chickadee math vector)
#:use-module (chickadee graphics color)
#:use-module (chickadee graphics engine)
#:use-module (chickadee graphics shader)
#:use-module (chickadee graphics texture)
#:use-module (srfi srfi-9)
#:export (make-pbr-material
pbr-material?
pbr-material-name
pbr-material-base-color-factor
pbr-material-base-color-texture
pbr-material-metallic-factor
pbr-material-roughness-factor
pbr-material-metallic-roughness-texture
pbr-material-normal-factor
pbr-material-normal-texture
pbr-material-occlusion-facgor
pbr-material-occlusion-texture
pbr-material-emissive-factor
pbr-material-emissive-texture
pbr-material-alpha-mode
pbr-material-alpha-cutoff
pbr-material-double-sided?
default-pbr-material
pbr-shader
shader-apply/pbr))
(define-shader-type <pbr-material>
make-pbr-material
pbr-material?
(local-field name pbr-material-name)
(float-vec3 base-color-factor pbr-material-base-color-factor)
(local-field base-color-texture pbr-material-base-color-texture)
(float metallic-factor pbr-material-metallic-factor)
(float roughness-factor pbr-material-roughness-factor)
(local-field metallic-roughness-texture pbr-material-metallic-roughness-texture)
(float-vec3 normal-factor pbr-material-normal-factor)
(local-field normal-texture pbr-material-normal-texture)
(float-vec3 occlusion-factor pbr-material-occlusion-factor)
(local-field occlusion-texture pbr-material-occlusion-texture)
(float-vec3 emissive-factor pbr-material-emissive-factor)
(local-field emissive-texture pbr-material-emissive-texture)
(local-field alpha-mode pbr-material-alpha-mode)
(float alpha-cutoff pbr-material-alpha-cutoff)
(bool double-sided? pbr-material-double-sided?))
(define default-pbr-material
(make-pbr-material #:name "default"
#:base-color-factor #v(1.0 1.0 1.0)
#:base-color-texture null-texture
#:metallic-factor 1.0
#:roughness-factor 1.0
#:metallic-roughness-texture null-texture
#:normal-factor #v(1.0 1.0 1.0)
#:normal-texture null-texture
#:occlusion-factor #v(1.0 1.0 1.0)
#:occlusion-texture null-texture
#:emissive-factor #v(1.0 1.0 1.0)
#:emissive-texture null-texture
#:alpha-mode 'opaque
#:alpha-cutoff 0.5
#:double-sided? #f))
(define-graphics-variable pbr-shader
;; TODO: Actually implement PBR. For now it's just the minimal amount
;; of code needed to render the base texture of a mesh.
(strings->shader
"
#ifdef GLSL330
layout (location = 0) in vec3 position;
layout (location = 1) in vec2 texcoord0;
#elif defined(GLSL130)
in vec3 position;
in vec2 texcoord0;
#elif defined(GLSL120)
attribute vec3 position;
attribute vec2 texcoord0;
#endif
#ifdef GLSL120
varying vec2 fragTex;
#else
out vec2 fragTex;
#endif
uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;
void main(void) {
fragTex = texcoord0;
gl_Position = projection * view * model * vec4(position.xyz, 1.0);
}
"
"
#ifdef GLSL120
attribute vec2 fragTex;
#else
in vec2 fragTex;
#endif
#ifdef GLSL330
out vec4 fragColor;
#endif
uniform vec3 baseColorFactor;
uniform sampler2D baseColorTexture;
void main (void) {
#ifdef GLSL330
fragColor = texture(baseColorTexture, fragTex) *
vec4(baseColorFactor, 1.0);
#else
gl_FragColor = texture2D(baseColorTexture, fragTex) *
vec4(baseColorFactor, 1.0);
#endif
}
"))
(define (shader-apply/pbr vertex-array material model-matrix view-matrix)
(let ((shader (graphics-variable-ref pbr-shader)))
(with-graphics-state ((g:texture-0 (pbr-material-base-color-texture material)))
(shader-apply shader vertex-array
#:model model-matrix
#:view view-matrix
#:projection (current-projection)
#:base-color-factor (pbr-material-base-color-factor material)))))
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