Implement alpha cutoff for materials

[libs/gl.git] / shaderlib / cooktorrance.glsl

diff --git a/shaderlib/cooktorrance.glsl b/shaderlib/cooktorrance.glsl
index f441a6d392088fe05f8152dc3430d2de1b701c3a..ad1a459d2e32932d9cb79a0501fb339b5ad6b7ba 100644 (file)
--- a/shaderlib/cooktorrance.glsl
+++ b/shaderlib/cooktorrance.glsl
@@ -13,6 +13,7 @@ struct PbrMaterialParameters
 uniform PbrMaterial
 {
        PbrMaterialParameters pbr_material;
+       float alpha_cutoff;
 };
 
 uniform sampler2D base_color_map;
@@ -29,6 +30,7 @@ layout(constant_id=auto) const bool use_occlusion_map = false;
 layout(constant_id=auto) const bool use_emission = false;
 layout(constant_id=auto) const bool use_emission_map = false;
 layout(constant_id=auto) const bool use_image_based_lighting = false;
+layout(constant_id=auto) const bool use_alpha_cutoff = false;
 
 #pragma MSP stage(fragment)
 virtual vec4 get_base_color()
@@ -74,7 +76,8 @@ virtual vec3 get_emission_color()
 /* Computes the diffuse reflection of the macrosurface */
 vec3 lambert_diffuse(vec3 base_color)
 {
-       // Scale by pi to get a result per steradian, suitable for integration
+       /* Scale by pi (cosine-weighted area of a hemisphere) because the light
+       scatters in every direction */
        return base_color/PI;
 }
 
@@ -118,7 +121,7 @@ vec3 fresnel_schlick(vec3 halfway, vec3 look, vec3 base_color, float metalness)
 }
 
 /* Computes the full contribution of a single light */
-vec3 cooktorrance_one_light_direct(vec3 normal, vec3 look, vec3 light, vec3 light_color, vec3 base_color, float metalness, float roughness)
+vec3 cooktorrance_one_light_direct(vec3 normal, vec3 look, vec3 light, vec3 base_color, float metalness, float roughness)
 {
        vec3 halfway = normalize(light-look);
        float ndist = normal_distribution_ggxtr(normal, halfway, roughness);
@@ -128,7 +131,7 @@ vec3 cooktorrance_one_light_direct(vec3 normal, vec3 look, vec3 light, vec3 ligh
        vec3 k_diff = (1.0-k_spec)*(1.0-metalness);
 
        float spec_denom = max(4.0*max(dot(normal, -look), 0.0)*max(dot(normal, light), 0.0), 0.001);
-       return max(dot(normal, light), 0.0)*light_color*(k_diff*lambert_diffuse(base_color)+k_spec*ndist*geom/spec_denom);
+       return max(dot(normal, light), 0.0)*(k_diff*lambert_diffuse(base_color)+k_spec*ndist*geom/spec_denom);
 }
 
 vec3 cooktorrance_environment(vec3 normal, vec3 look, vec3 base_color, float metalness, float roughness)
@@ -155,9 +158,9 @@ vec3 cooktorrance_lighting(vec3 normal, vec3 look, vec3 base_color, float metaln
        for(int i=0; i<max_lights; ++i)
                if(light_sources[i].type!=0)
                {
-                       vec3 light = get_light_direction(i);
-                       float shadow = get_shadow_factor(i);
-                       color += cooktorrance_one_light_direct(normal, look, light, light_sources[i].color, base_color, metalness, roughness)*shadow;
+                       IncomingLight incoming = get_incoming_light(i, world_vertex.xyz);
+                       float shadow = get_shadow_factor(i, world_vertex);
+                       color += cooktorrance_one_light_direct(normal, look, incoming.direction, base_color, metalness, roughness)*incoming.color*shadow;
                }
 
        color += cooktorrance_environment(normal, look, base_color, metalness, roughness);
@@ -172,10 +175,13 @@ vec3 cooktorrance_lighting(vec3 normal, vec3 look, vec3 base_color, float metaln
 
 void main()
 {
+       vec4 base_color = get_base_color();
+       if(use_alpha_cutoff && base_color.a<alpha_cutoff)
+               discard;
+
        vec3 normal = get_fragment_normal();
        vec3 look = normalize(world_look_dir);
 
-       vec4 base_color = get_base_color();
        float metalness = get_metalness_value();
        float roughness = get_roughness_value();