Improvements for shadow mapping

Depth bias is now configurable, and a darkness parameter was added.

diff --git a/source/programbuilder.cpp b/source/programbuilder.cpp
index 46f7c153b5fbb9132910875a48a13353a2941e68..1e07c1e555b03af9e271db964d398a72dbab95f8 100644 (file)
--- a/source/programbuilder.cpp
+++ b/source/programbuilder.cpp
@@ -53,7 +53,8 @@ const ProgramBuilder::StandardVariable ProgramBuilder::standard_variables[] =
        { FRAGMENT, "rgb_light", "vec3", "vec3(l_diffuse+l_specular)", "!mp" },
        { FRAGMENT, "rgb_light", "vec3", "l_diffuse*gl_FrontLightProduct[0].diffuse.rgb", "m!p" },
        { FRAGMENT, "rgb_light", "vec3", "l_diffuse*gl_FrontLightProduct[0].diffuse.rgb+l_specular*gl_FrontLightProduct[0].specular.rgb", "mp" },
-       { FRAGMENT, "l_shadow", "float", "shadow2D(shadow, shd_vertex).r", 0 },
+       { FRAGMENT, "l_shadow", "float", "mix(1.0, shadow_sample, shadow_darkness)", 0 },
+       { FRAGMENT, "shadow_sample", "float", "shadow2D(shadow, shd_vertex).r", 0 },
        { FRAGMENT, "l_diffuse", "float", "max(dot(n_zzz_normal, n_zzz_light_dir), 0.0)", 0 },
        { FRAGMENT, "l_specular", "float", "pow(max(dot(n_zzz_half_vec, n_zzz_normal), 0.0), gl_FrontMaterial.shininess)", 0 },
        { FRAGMENT, "n_zzz_half_vec", "vec3", "normalize(zzz_light_dir-zzz_incident_dir)", 0 },
@@ -87,6 +88,7 @@ const ProgramBuilder::StandardVariable ProgramBuilder::standard_variables[] =
        { UNIFORM, "shadow_unit", "int", 0, 0 },
        { UNIFORM, "texture", "sampler2D", 0, 0 },
        { UNIFORM, "shadow", "sampler2DShadow", 0, 0 },
+       { UNIFORM, "shadow_darkness", "float", 0, 0 },
        { UNIFORM, "normalmap", "sampler2D", 0, 0 },
 
        // Terminator entry

diff --git a/source/shadowmap.cpp b/source/shadowmap.cpp
index ea4982fe9f60bb67e31c66b2761f6e70331056c9..b930315f626140d43c461910a8c8bfc01fdfd580 100644 (file)
--- a/source/shadowmap.cpp
+++ b/source/shadowmap.cpp
@@ -18,7 +18,8 @@ ShadowMap::ShadowMap(unsigned s, const Renderable &r, const Light &l):
        Effect(r),
        size(s),
        light(l),
-       radius(1)
+       radius(1),
+       depth_bias(4)
 {
        depth_buf.set_min_filter(LINEAR);
        depth_buf.set_compare_enabled(true);
@@ -27,6 +28,7 @@ ShadowMap::ShadowMap(unsigned s, const Renderable &r, const Light &l):
        depth_buf.storage(DEPTH_COMPONENT, size, size);
        fbo.attach(DEPTH_ATTACHMENT, depth_buf, 0);
 
+       set_darkness(0.7);
        set_texture_unit(3);
 }
 
@@ -36,6 +38,22 @@ void ShadowMap::set_target(const Vector3 &t, float r)
        radius = r;
 }
 
+void ShadowMap::set_darkness(float d)
+{
+       if(d<0.0f || d>1.0f)
+               throw invalid_argument("ShadowMap::set_darkness");
+
+       shdata.uniform("shadow_darkness", d);
+}
+
+void ShadowMap::set_depth_bias(float b)
+{
+       if(b<0.0f)
+               throw invalid_argument("ShadowMap::set_depth_bias");
+
+       depth_bias = b;
+}
+
 void ShadowMap::set_texture_unit(unsigned u)
 {
        unit = u;
@@ -118,7 +136,7 @@ void ShadowMap::render(Renderer &renderer, const Tag &tag) const
        TexGen tg_s, tg_t, tg_r;
        tg_s.set_plane(Vector4(matrix[0]/diam, matrix[4]/diam, matrix[8]/diam, matrix[12]/diam+0.5f));
        tg_t.set_plane(Vector4(matrix[1]/diam, matrix[5]/diam, matrix[9]/diam, matrix[13]/diam+0.5f));
-       tg_r.set_plane(Vector4(-matrix[2]/diam, -matrix[6]/diam, -matrix[10]/diam, 0.5f-matrix[14]/diam-4.0f/size));
+       tg_r.set_plane(Vector4(-matrix[2]/diam, -matrix[6]/diam, -matrix[10]/diam, 0.5f-matrix[14]/diam-depth_bias/size));
        tg_s.bind_to(SCOORD);
        tg_t.bind_to(TCOORD);
        tg_r.bind_to(RCOORD);

diff --git a/source/shadowmap.h b/source/shadowmap.h
index af3cf6f72c2b9af398e7faa317f6fdeaa810627f..986e0d96d039936b56758495da9a84954c007074 100644 (file)
--- a/source/shadowmap.h
+++ b/source/shadowmap.h
@@ -29,6 +29,7 @@ private:
        Texture2D depth_buf;
        Vector3 target;
        float radius;
+       float depth_bias;
        ProgramData shdata;
 
 public:
@@ -39,8 +40,20 @@ public:
        covered by the ShadowMap. */
        void set_target(const Vector3 &, float);
 
+       /** Sets the darkness of shadows.  Must be in the range between 0.0 and 1.0,
+       inclusive.  Only usable with shaders, and provided through the
+       shadow_darkness uniform. */
+       void set_darkness(float);
+
+       /** Sets a distance beyond objects from which the shadow starts.  Expressed
+       in pixel-sized units.  Must be positive; values less than 1.0 are not
+       recommended.  Larger values produce less depth artifacts, but may prevent
+       thin objects from casting shadows on nearby sufraces. */
+       void set_depth_bias(float);
+
        /** Sets the texture unit to bind the shadow map to during the rendering
-       phase.  The default is texture unit 3. */
+       phase.  Provided to shaders through the shadow and shadow_unit uniforms.
+       The default is texture unit 3. */
        void set_texture_unit(unsigned);
 
        virtual void render(Renderer &, const Tag &) const;