1 files changed, 48 insertions, 0 deletions
diff --git a/engine/src/core-data/Common/ShaderLib/Lighting.glsllib b/engine/src/core-data/Common/ShaderLib/Lighting.glsllib
new file mode 100644
index 0000000..4d1b404
--- /dev/null
+++ b/engine/src/core-data/Common/ShaderLib/Lighting.glsllib
@@ -0,0 +1,48 @@
+#ifndef NUM_LIGHTS
+    #define NUM_LIGHTS 4
+#endif
+
+uniform mat4 g_ViewMatrix;
+uniform vec4 g_LightPosition[NUM_LIGHTS];
+uniform vec4 g_g_LightColor[NUM_LIGHTS];
+uniform float m_Shininess;
+
+float Lighting_Diffuse(vec3 norm, vec3 lightdir){
+    return max(0.0, dot(norm, lightdir));
+}
+
+float Lighting_Specular(vec3 norm, vec3 viewdir, vec3 lightdir, float shiny){
+    vec3 refdir = reflect(-lightdir, norm);
+    return pow(max(dot(refdir, viewdir), 0.0), shiny);
+}
+
+void Lighting_Direction(vec3 worldPos, vec4 color, vec4 position, out vec4 lightDir){
+    float posLight = step(0.5, color.w);
+    vec3 tempVec = position.xyz * sign(posLight - 0.5) - (worldPos * posLight);
+    float dist = length(tempVec);
+
+    lightDir.w = clamp(1.0 - position.w * dist * posLight, 0.0, 1.0);
+    lightDir.xyz = tempVec / dist;
+}
+
+void Lighting_ComputePS(vec3 tanNormal, mat3 tbnMat,
+                     int lightCount, out vec3 outDiffuse, out vec3 outSpecular){
+   // find tangent view dir & vert pos
+   vec3 tanViewDir = viewDir * tbnMat;
+
+   for (int i = 0; i < lightCount; i++){
+       // find light dir in tangent space, works for point & directional lights
+       vec4 wvLightPos = (g_ViewMatrix * vec4(g_LightPosition[i].xyz, g_LightColor[i].w));
+       wvLightPos.w = g_LightPosition[i].w;
+
+       vec4 tanLightDir;
+       Lighting_Direction(wvPosition, g_LightColor[i], wvLightPos, tanLightDir);
+       tanLightDir.xyz = tanLightDir.xyz * tbnMat;
+
+       vec3 lightScale = g_LightColor[i].rgb * tanLightDir.w;
+       float specular = Lighting_Specular(tanNormal, tanViewDir, tanLightDir.xyz, m_Shininess);
+       float diffuse = Lighting_Diffuse(tanNormal, tanLightDir.xyz);
+       outSpecular += specular * lightScale * step(0.01, diffuse) * g_LightColor[i].rgb;
+       outDiffuse += diffuse * lightScale * g_LightColor[i].rgb;
+   }
+}