diff options
Diffstat (limited to 'src/osd/modules/render/bgfx/shaders/chains/crt-geom/fs_mipmap8.sc')
-rw-r--r-- | src/osd/modules/render/bgfx/shaders/chains/crt-geom/fs_mipmap8.sc | 148 |
1 files changed, 148 insertions, 0 deletions
diff --git a/src/osd/modules/render/bgfx/shaders/chains/crt-geom/fs_mipmap8.sc b/src/osd/modules/render/bgfx/shaders/chains/crt-geom/fs_mipmap8.sc new file mode 100644 index 00000000000..0f86bdbc7ba --- /dev/null +++ b/src/osd/modules/render/bgfx/shaders/chains/crt-geom/fs_mipmap8.sc @@ -0,0 +1,148 @@ +$input v_texCoord + +#include "common.sh" + +SAMPLER2D(s_screen, 0); +SAMPLER2D(s_mipmap, 1); + +uniform vec4 u_tex_size0; +uniform vec4 u_tex_size1; +uniform vec4 u_smooth; + +/* + * Based loosely on the idea outlined at + * https://nyorain.github.io/mipmap-compute-shader.html + * Each higher mipmap level is delayed by one frame. + * + * A rectangle containing (1,1) has the last mipmap level + * (normally a single pixel containing the average of the frame), + * passed through a two-tap IIR temporal filter. + */ + +const vec2 v05 = vec2(0.5,0.5); + +// pix has integer coordinates -> average four pixels using bilinear filtering +vec3 sample_screen(vec2 pix) +{ + vec2 border = step(-0.5, u_tex_size0.xy - pix); + float weight = border.x * border.y; + + // avoid boundary! if dimensions are odd, average 1 or 2 pixels + vec2 x = clamp(pix, vec2_splat(0.0), u_tex_size0.xy - v05); + // if we're at the boundary, include weight factor + // -> effectively always average 4 pixels, with some of them possibly zero + border = clamp(u_tex_size0.xy-x,0.0,1.0); + weight *= border.x * border.y; + + vec3 tex = texture2D(s_screen, x / u_tex_size0.xy).rgb; + + return tex * vec3_splat(weight); +} + +vec3 sample_mipmap(vec2 pix, vec2 offset, vec2 size) +{ + vec2 border = step(-0.5, size - pix) * step(-0.5, pix); + float weight = border.x * border.y; + + // avoid boundary! if dimensions are odd, average 1 or 2 pixels + vec2 x = clamp(pix, vec2_splat(0.0), size - v05); + // if we're at the boundary, include weight factor + // -> effectively always average 4 pixels, with some of them possibly zero + border = clamp(size-x,0.0,1.0); + weight *= border.x * border.y; + + vec3 tex = texture2D(s_mipmap, (x + offset) / u_tex_size0.xy).rgb; + + return tex * vec3_splat(weight); +} + +void main() +{ + vec2 pix = v_texCoord.xy * u_tex_size0.xy; + vec2 x = pix*vec2_splat(8.0); + if (pix.x < u_tex_size0.x * 0.5) { + // first level: sample from screen texture + + // sample 4x4 grid + // each sample uses bilinear filtering to average a 2x2 region + // overall reduction by 8x8 + vec3 tex = ( sample_screen(x + vec2(-3.0,-3.0)) + + sample_screen(x + vec2(-3.0,-1.0)) + + sample_screen(x + vec2(-3.0, 1.0)) + + sample_screen(x + vec2(-3.0, 3.0)) + + sample_screen(x + vec2(-1.0,-3.0)) + + sample_screen(x + vec2(-1.0,-1.0)) + + sample_screen(x + vec2(-1.0, 1.0)) + + sample_screen(x + vec2(-1.0, 3.0)) + + sample_screen(x + vec2( 1.0,-3.0)) + + sample_screen(x + vec2( 1.0,-1.0)) + + sample_screen(x + vec2( 1.0, 1.0)) + + sample_screen(x + vec2( 1.0, 3.0)) + + sample_screen(x + vec2( 3.0,-3.0)) + + sample_screen(x + vec2( 3.0,-1.0)) + + sample_screen(x + vec2( 3.0, 1.0)) + + sample_screen(x + vec2( 3.0, 3.0)) ) * 0.0625; + + gl_FragColor = vec4(tex.rgb,1.0); + } else { + // higher levels: sample from mipmap texture + vec2 newsize = u_tex_size0.xy; // size of texture being sampled + float fac = 8.0; // keep track of the linear reduction factor + float dx = u_tex_size0.x; + vec2 offset = vec2_splat(0.0); + vec2 offset0 = offset; + bool fc = false; + + for (int i = 0; i < 3; i++) { // 3 is sufficient for dimensions up to 4k + // place subsequent levels to the right + if (pix.x > dx * 0.5) { + dx = dx * 0.5; + newsize = ceil(newsize*v05*v05*v05); // size of sampled texture is eighthed + fac *= 8.0; + offset0 = offset; + offset.x = offset.x + dx; + pix.x -= dx; + x = pix * vec2_splat(8.0); + if (newsize.x < 8.5 && newsize.y < 8.5) { // reducing to a single pixel + fc = true; + break; + } + } else break; + } + + if (fc) + x = vec2(4.0,4.0); + + vec3 tex = ( sample_mipmap(x + vec2(-3.0,-3.0),offset0,newsize) + + sample_mipmap(x + vec2(-3.0,-1.0),offset0,newsize) + + sample_mipmap(x + vec2(-3.0, 1.0),offset0,newsize) + + sample_mipmap(x + vec2(-3.0, 3.0),offset0,newsize) + + sample_mipmap(x + vec2(-1.0,-3.0),offset0,newsize) + + sample_mipmap(x + vec2(-1.0,-1.0),offset0,newsize) + + sample_mipmap(x + vec2(-1.0, 1.0),offset0,newsize) + + sample_mipmap(x + vec2(-1.0, 3.0),offset0,newsize) + + sample_mipmap(x + vec2( 1.0,-3.0),offset0,newsize) + + sample_mipmap(x + vec2( 1.0,-1.0),offset0,newsize) + + sample_mipmap(x + vec2( 1.0, 1.0),offset0,newsize) + + sample_mipmap(x + vec2( 1.0, 3.0),offset0,newsize) + + sample_mipmap(x + vec2( 3.0,-3.0),offset0,newsize) + + sample_mipmap(x + vec2( 3.0,-1.0),offset0,newsize) + + sample_mipmap(x + vec2( 3.0, 1.0),offset0,newsize) + + sample_mipmap(x + vec2( 3.0, 3.0),offset0,newsize) ) * 0.0625; + + if (fc) { // this sample yields average over the whole screen + // apply a compensation for the zeros included in the 8^n average + float f = fac*fac / (u_tex_size0.x * u_tex_size0.y); + vec3 col = tex * vec3_splat(f); + if (v_texCoord.y * u_tex_size1.y < ( offset0.y + u_tex_size1.y ) * 0.5) { + gl_FragColor = vec4(col,1.0); + } else { + // we are near (1,1): in this region include the temporal filter + vec4 old = texture2D(s_mipmap, v_texCoord.xy); + gl_FragColor = vec4(mix(col,old.rgb,u_smooth.x),1.0); + } + } else { + gl_FragColor = vec4(tex.rgb,1.0); + } + } +} |