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Diffstat (limited to 'src/osd/modules/opengl/shader/glsl_bilinear_idx16_lut.fsh')
-rw-r--r--src/osd/modules/opengl/shader/glsl_bilinear_idx16_lut.fsh55
1 files changed, 55 insertions, 0 deletions
diff --git a/src/osd/modules/opengl/shader/glsl_bilinear_idx16_lut.fsh b/src/osd/modules/opengl/shader/glsl_bilinear_idx16_lut.fsh
new file mode 100644
index 00000000000..ef0030b7519
--- /dev/null
+++ b/src/osd/modules/opengl/shader/glsl_bilinear_idx16_lut.fsh
@@ -0,0 +1,55 @@
+
+#pragma optimize (on)
+#pragma debug (off)
+
+uniform sampler2D color_texture;
+uniform sampler2D colortable_texture;
+uniform vec2 colortable_sz; // ct size
+uniform vec2 colortable_pow2_sz; // pow2 ct size
+uniform vec2 color_texture_pow2_sz; // pow2 tex size
+
+vec4 lutTex2D(in vec2 texcoord)
+{
+ vec4 color_tex;
+ vec2 color_map_coord;
+
+ // normalized texture coordinates ..
+ color_tex = texture2D(color_texture, texcoord);
+
+ // GL_UNSIGNED_SHORT GL_ALPHA in ALPHA16 conversion:
+ // general: f = c / ((2*N)-1), c color bitfield, N number of bits
+ // ushort: c = ((2**16)-1)*f;
+ color_map_coord.x = floor( 65535.0 * color_tex.a + 0.5 );
+
+ // map it to the 2D lut table
+ color_map_coord.y = floor(color_map_coord.x/colortable_sz.x);
+ color_map_coord.x = mod(color_map_coord.x,colortable_sz.x);
+
+ return texture2D(colortable_texture, (color_map_coord+vec2(0.5)) / colortable_pow2_sz);
+}
+
+void main()
+{
+ vec2 xy = gl_TexCoord[0].st;
+
+ // mix(x,y,a): x*(1-a) + y*a
+ //
+ // bilinear filtering includes 2 mix:
+ //
+ // pix1 = tex[x0][y0] * ( 1 - u_ratio ) + tex[x1][y0] * u_ratio
+ // pix2 = tex[x0][y1] * ( 1 - u_ratio ) + tex[x1][y1] * u_ratio
+ // fin = pix1 * ( 1 - v_ratio ) + pix2 * v_ratio
+ //
+ // so we can use the build in mix function for these 2 computations ;-)
+ //
+ vec2 uv_ratio = fract(xy*color_texture_pow2_sz); // xy*color_texture_pow2_sz - floor(xy*color_texture_pow2_sz);
+ vec2 one = 1.0/color_texture_pow2_sz;
+
+ vec4 col1, col2;
+
+ col1 = mix( lutTex2D(xy ), lutTex2D(xy + vec2(one.x, 0.0)), uv_ratio.x);
+ col2 = mix( lutTex2D(xy + vec2(0.0, one.y)), lutTex2D(xy + one ), uv_ratio.x);
+
+ gl_FragColor = mix ( col1, col2, uv_ratio.y );
+}
+