1 /* This Source Code Form is subject to the terms of the Mozilla Public
2 * License, v. 2.0. If a copy of the MPL was not distributed with this
3 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
5 flat varying highp vec4 vTransformBounds;
7 #ifdef WR_VERTEX_SHADER
9 #define VECS_PER_TRANSFORM 8U
10 uniform HIGHP_SAMPLER_FLOAT sampler2D sTransformPalette;
12 void rectangle_aa_vertex(vec4 local_bounds) {
13 vTransformBounds = local_bounds;
22 Transform fetch_transform(int id) {
25 transform.is_axis_aligned = (id >> 23) == 0;
26 int index = id & 0x007fffff;
28 // Create a UV base coord for each 8 texels.
29 // This is required because trying to use an offset
30 // of more than 8 texels doesn't work on some versions
32 ivec2 uv = get_fetch_uv(index, VECS_PER_TRANSFORM);
33 ivec2 uv0 = ivec2(uv.x + 0, uv.y);
35 transform.m[0] = TEXEL_FETCH(sTransformPalette, uv0, 0, ivec2(0, 0));
36 transform.m[1] = TEXEL_FETCH(sTransformPalette, uv0, 0, ivec2(1, 0));
37 transform.m[2] = TEXEL_FETCH(sTransformPalette, uv0, 0, ivec2(2, 0));
38 transform.m[3] = TEXEL_FETCH(sTransformPalette, uv0, 0, ivec2(3, 0));
40 transform.inv_m[0] = TEXEL_FETCH(sTransformPalette, uv0, 0, ivec2(4, 0));
41 transform.inv_m[1] = TEXEL_FETCH(sTransformPalette, uv0, 0, ivec2(5, 0));
42 transform.inv_m[2] = TEXEL_FETCH(sTransformPalette, uv0, 0, ivec2(6, 0));
43 transform.inv_m[3] = TEXEL_FETCH(sTransformPalette, uv0, 0, ivec2(7, 0));
48 // Return the intersection of the plane (set up by "normal" and "point")
49 // with the ray (set up by "ray_origin" and "ray_dir"),
50 // writing the resulting scaler into "t".
51 bool ray_plane(vec3 normal, vec3 pt, vec3 ray_origin, vec3 ray_dir, out float t)
53 float denom = dot(normal, ray_dir);
54 if (abs(denom) > 1e-6) {
55 vec3 d = pt - ray_origin;
56 t = dot(d, normal) / denom;
63 // Apply the inverse transform "inv_transform"
64 // to the reference point "ref" in CSS space,
65 // producing a local point on a Transform plane,
66 // set by a base point "a" and a normal "n".
67 vec4 untransform(vec2 ref, vec3 n, vec3 a, mat4 inv_transform) {
68 vec3 p = vec3(ref, -10000.0);
69 vec3 d = vec3(0, 0, 1.0);
72 // get an intersection of the Transform plane with Z axis vector,
73 // originated from the "ref" point
74 ray_plane(n, a, p, d, t);
75 float z = p.z + d.z * t; // Z of the visible point on the Transform
77 vec4 r = inv_transform * vec4(ref, z, 1.0);
81 // Given a CSS space position, transform it back into the Transform space.
82 vec4 get_node_pos(vec2 pos, Transform transform) {
83 // get a point on the scroll node plane
84 vec4 ah = transform.m * vec4(0.0, 0.0, 0.0, 1.0);
85 vec3 a = ah.xyz / ah.w;
87 // get the normal to the scroll node plane
88 vec3 n = transpose(mat3(transform.inv_m)) * vec3(0.0, 0.0, 1.0);
89 return untransform(pos, n, a, transform.inv_m);
92 #endif //WR_VERTEX_SHADER
94 #ifdef WR_FRAGMENT_SHADER
96 // Assume transform bounds are set to a large scale to signal they are invalid.
97 bool has_valid_transform_bounds() {
98 return vTransformBounds.w < 1.0e15;
101 float rectangle_aa_fragment(vec2 local_pos) {
102 // Ideally we want to track distances in screen space after transformation
103 // as signed distance calculations lose context about the direction vector
104 // to exit the geometry, merely remembering the minimum distance to the
105 // exit. However, we can't always sanely track distances in screen space
106 // due to perspective transforms, clipping, and other concerns, so we do
107 // this in local space. However, this causes problems tracking distances
108 // in local space when attempting to scale by a uniform AA range later in
109 // the presence of a transform which actually has non-uniform scaling.
111 // To work around this, we independently track the distances on the local
112 // space X and Y axes and then scale them by the independent AA ranges (as
113 // computed from fwidth derivatives) for the X and Y axes. This can break
114 // down at certain angles (45 degrees or close to it), but still gives a
115 // better approximation of screen-space distances in the presence of non-
116 // uniform scaling for other rotations.
118 // Get signed distance from local rect bounds.
119 vec2 d = signed_distance_rect_xy(
125 // Find the appropriate distance to apply the AA smoothstep over.
126 vec2 aa_range = compute_aa_range_xy(local_pos);
128 // Only apply AA to fragments outside the signed distance field.
129 return distance_aa_xy(aa_range, d);
132 float rectangle_aa_rough_fragment(vec2 local_pos) {
133 return point_inside_rect(
140 #endif //WR_FRAGMENT_SHADER