From 89b5603110c47e30450ce05573c6b95ef38d8fd7 Mon Sep 17 00:00:00 2001
From: Tomasz Kramkowski <tk@the-tk.com>
Date: Mon, 30 Apr 2018 12:51:12 +0100
Subject: Implement basic fixed point light source and phong shading

This patch places a single point light source in the scene and
implements view-space phong shading around it. This is in preparation
for texture values being fed in from a set of textures.
---
 frag.glsl | 21 +++++++++++++++++++--
 vert.glsl | 14 +++++++++++---
 2 files changed, 30 insertions(+), 5 deletions(-)

diff --git a/frag.glsl b/frag.glsl
index c48ee57..41d98ad 100644
--- a/frag.glsl
+++ b/frag.glsl
@@ -2,9 +2,26 @@
 // SPDX-License-Identifier: MIT
 #version 330 core
 out vec4 color;
-in vec3 vcolor;
+in vec3 vnorm;
+in vec3 fpos;
+in vec3 lipos;
 
 void main()
 {
-	color = vec4(vcolor, 1.0);
+	vec3 objco = { 1.0, 0.5, 0.31 };
+	vec3 lico = { 1.0, 1.0, 1.0 };
+
+	float amb = 0.1;
+
+	vec3 norm = normalize(vnorm);
+	vec3 lidir = normalize(lipos - fpos);
+	float dif = max(dot(norm, lidir), 0.0);
+
+	float spestr = 0.5;
+	vec3 vwdir = normalize(-fpos);
+	vec3 redir = reflect(-lidir, norm);
+
+	float spe = spestr * pow(max(dot(vwdir, redir), 0.0), 32);
+
+	color = vec4((amb + dif + spe) * lico * objco, 1.0);
 }
diff --git a/vert.glsl b/vert.glsl
index d33cc47..5e4e43a 100644
--- a/vert.glsl
+++ b/vert.glsl
@@ -2,16 +2,24 @@
 // SPDX-License-Identifier: MIT
 #version 330 core
 layout (location = 0) in vec3 pos;
-layout (location = 1) in vec3 normal;
+layout (location = 1) in vec3 norm;
 layout (location = 2) in vec2 uv;
 
-out vec3 vcolor;
+out vec3 vnorm;
+out vec3 fpos;
+out vec3 lipos;
+
 uniform mat4 model;
 uniform mat4 view;
 uniform mat4 proj;
 
 void main()
 {
+	vec3 light = { 1.2, 1.0, 2.0 };
+
 	gl_Position = proj * view * model * vec4(pos, 1.0);
-	vcolor = normal;
+	fpos = vec3(view * model * vec4(pos, 1.0));
+	// TODO: Try to work out how to only do this ONCE in C or see if it matters
+	vnorm = mat3(transpose(inverse(view * model))) * norm;
+	lipos = vec3(view * vec4(light, 1.0));
 }
-- 
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