Use non-random sequences to initialize ambient occlusion data

[libs/gl.git] / source / effects / ambientocclusion.cpp

diff --git a/source/effects/ambientocclusion.cpp b/source/effects/ambientocclusion.cpp
index a10fa838e7b3b1d0f2da41c1f4f3b029a97df92e..a407c2d9918621b3aa9f057fd93597845635f1e9 100644 (file)
--- a/source/effects/ambientocclusion.cpp
+++ b/source/effects/ambientocclusion.cpp
@@ -13,19 +13,38 @@ namespace Msp {
 namespace GL {
 
 AmbientOcclusion::AmbientOcclusion(unsigned w, unsigned h, float):
+       rotate_lookup(get_or_create_rotate_lookup()),
        occlude_target(w, h, (RENDER_COLOR,R8)),
        occlude_shader(Resources::get_global().get<Program>("_ambientocclusion_occlude.glsl.shader")),
        combine_shader(Resources::get_global().get<Program>("_ambientocclusion_combine.glsl.shader")),
        quad(Resources::get_global().get<Mesh>("_fullscreen_quad.mesh")),
        linear_sampler(Resources::get_global().get<Sampler>("_linear_clamp.samp")),
-       nearest_sampler(Resources::get_global().get<Sampler>("_nearest_clamp.samp"))
+       nearest_clamp_sampler(Resources::get_global().get<Sampler>("_nearest_clamp.samp")),
+       nearest_sampler(Resources::get_global().get<Sampler>("_nearest.samp"))
 {
-       unsigned seed = 1;
-       rotate_lookup.storage(RGBA8, 4, 4, 1);
+       set_n_samples(16);
+       set_occlusion_radius(0.5f);
+       set_darkness(1.0f);
+       set_edge_depth_threshold(0.1f);
+}
+
+const Texture2D &AmbientOcclusion::get_or_create_rotate_lookup()
+{
+       Resources &resources = Resources::get_global();
+
+       static const string name = "_ambientocclusion_rotate.tex2d";
+       Texture2D *rotate_lookup = resources.find<Texture2D>(name);
+       if(rotate_lookup)
+               return *rotate_lookup;
+
+       rotate_lookup = new Texture2D;
+       rotate_lookup->storage(RGBA8, 4, 4, 1);
+       resources.add(name, rotate_lookup);
+
        unsigned char data[64];
        for(unsigned i=0; i<16; ++i)
        {
-               Geometry::Angle<float> a = Geometry::Angle<float>::from_turns(random(seed));
+               Geometry::Angle<float> a = Geometry::Angle<float>::from_turns(i*7/16.0f);
                unsigned char c = (cos(a)*0.5f+0.5f)*255;
                unsigned char s = (sin(a)*0.5f+0.5f)*255;
                data[i*4  ] = c;
@@ -33,19 +52,17 @@ AmbientOcclusion::AmbientOcclusion(unsigned w, unsigned h, float):
                data[i*4+2] = 255-s;
                data[i*4+3] = ((i+i/4)%2)*255;
        }
-       rotate_lookup.image(0, data);
+       rotate_lookup->image(0, data);
 
-       set_n_samples(16);
-       set_occlusion_radius(0.5f);
-       set_darkness(1.0f);
-       set_edge_depth_threshold(0.1f);
+       return *rotate_lookup;
 }
 
-float AmbientOcclusion::random(unsigned &seed)
+float AmbientOcclusion::radical_inverse(unsigned n)
 {
-       static const unsigned modulus = (1U<<31)-1;
-       seed = (static_cast<UInt64>(seed)*48271)%modulus;  // minstd
-       return static_cast<float>(seed)/(modulus-1);
+       unsigned inv = ((n&0x55)<<1) | ((n&0xAA)>>1);
+       inv = ((inv&0x33)<<2) | ((inv&0xCC)>>2);
+       inv = ((inv&0x0F)<<4) | ((inv&0xF0)>>4);
+       return inv/256.0f;
 }
 
 void AmbientOcclusion::set_n_samples(unsigned n)
@@ -53,13 +70,14 @@ void AmbientOcclusion::set_n_samples(unsigned n)
        if(n<1 || n>32)
                throw out_of_range("AmbientOcclusion::set_n_samples");
 
-       unsigned seed = 1;
-       float radius_divisor = (n-1)*(n-1);
        Vector3 sample_points[32];
        for(unsigned i=0; i<n; ++i)
        {
-               Vector3 v(random(seed)-0.5f, random(seed)-0.5f, random(seed)-0.5f);
-               sample_points[i] = normalize(v)*(0.1f+0.9f*i*i/radius_divisor);
+               float z = static_cast<float>(i)/n;
+               float r = sqrt(1.0f-z*z);
+               float d = radical_inverse(i);
+               Geometry::Angle<float> a = Geometry::Angle<float>::from_turns(d);
+               sample_points[i] = Vector3(cos(a)*r, sin(a)*r, z)*(0.1f+0.9f*d*d);
        }
        shdata.uniform3_array("sample_points", n, &sample_points[0].x);
        shdata.uniform("n_samples", static_cast<int>(n));
@@ -83,8 +101,8 @@ void AmbientOcclusion::set_edge_depth_threshold(float edt)
 void AmbientOcclusion::render(Renderer &renderer, const Texture2D &color, const Texture2D &depth)
 {
        Renderer::Push push(renderer);
-       renderer.set_texture("source", &color, &nearest_sampler);
-       renderer.set_texture("depth", &depth, &nearest_sampler);
+       renderer.set_texture("source", &color, &nearest_clamp_sampler);
+       renderer.set_texture("depth", &depth, &nearest_clamp_sampler);
        renderer.set_texture("occlusion", &occlude_target.get_target_texture(RENDER_COLOR), &linear_sampler);
        renderer.set_texture("rotate", &rotate_lookup, &nearest_sampler);
        renderer.set_shader_program(&occlude_shader, &shdata);