1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
|
/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
Texture2D InputTexture : register(t0);
SamplerState InputSampler : register(s0);
Texture2D GradientTexture : register(t1);
SamplerState GradientSampler : register(s1);
cbuffer constants : register(b0)
{
// Precalculate as much as we can!
float3 diff : packoffset(c0.x);
float2 center1 : packoffset(c1.x);
float A : packoffset(c1.z);
float radius1 : packoffset(c1.w);
float sq_radius1 : packoffset(c2.x);
// The next two values are used for a hack to compensate for an apparent
// bug in D2D where the GradientSampler SamplerState doesn't get the
// correct addressing modes.
float repeat_correct : packoffset(c2.y);
float allow_odd : packoffset(c2.z);
float3x2 transform : packoffset(c3.x);
}
float4 SampleRadialGradientPS(
float4 clipSpaceOutput : SV_POSITION,
float4 sceneSpaceOutput : SCENE_POSITION,
float4 texelSpaceInput0 : TEXCOORD0
) : SV_Target
{
// Radial gradient painting is defined as the set of circles whose centers
// are described by C(t) = (C2 - C1) * t + C1; with radii
// R(t) = (R2 - R1) * t + R1; for R(t) > 0. This shader solves the
// quadratic equation that arises when calculating t for pixel (x, y).
//
// A more extensive derrivation can be found in the pixman radial gradient
// code.
float2 p = float2(sceneSpaceOutput.x * transform._11 + sceneSpaceOutput.y * transform._21 + transform._31,
sceneSpaceOutput.x * transform._12 + sceneSpaceOutput.y * transform._22 + transform._32);
float3 dp = float3(p - center1, radius1);
// dpx * dcx + dpy * dcy + r * dr
float B = dot(dp, diff);
float C = pow(dp.x, 2) + pow(dp.y, 2) - sq_radius1;
float det = pow(B, 2) - A * C;
float sqrt_det = sqrt(abs(det));
float2 t = (B + float2(sqrt_det, -sqrt_det)) / A;
float2 isValid = step(float2(-radius1, -radius1), t * diff.z);
float upper_t = lerp(t.y, t.x, isValid.x);
// Addressing mode bug work-around.. first let's see if we should consider odd repetitions separately.
float oddeven = abs(fmod(floor(upper_t), 2)) * allow_odd;
// Now let's calculate even or odd addressing in a branchless manner.
float upper_t_repeated = ((upper_t - floor(upper_t)) * (1.0f - oddeven)) + ((ceil(upper_t) - upper_t) * oddeven);
float4 output = GradientTexture.Sample(GradientSampler, float2(upper_t * (1.0f - repeat_correct) + upper_t_repeated * repeat_correct, 0.5));
// Premultiply
output.rgb *= output.a;
// Multiply the output color by the input mask for the operation.
output *= InputTexture.Sample(InputSampler, texelSpaceInput0.xy);
// In order to compile for PS_4_0_level_9_3 we need to be branchless.
// This is essentially returning nothing, i.e. bailing early if:
// det < 0 || max(isValid.x, isValid.y) <= 0
return output * abs(step(max(isValid.x, isValid.y), 0) - 1.0f) * step(0, det);
};
float4 SampleRadialGradientA0PS(
float4 clipSpaceOutput : SV_POSITION,
float4 sceneSpaceOutput : SCENE_POSITION,
float4 texelSpaceInput0 : TEXCOORD0
) : SV_Target
{
// This simpler shader is used for the degenerate case where A is 0,
// i.e. we're actually solving a linear equation.
float2 p = float2(sceneSpaceOutput.x * transform._11 + sceneSpaceOutput.y * transform._21 + transform._31,
sceneSpaceOutput.x * transform._12 + sceneSpaceOutput.y * transform._22 + transform._32);
float3 dp = float3(p - center1, radius1);
// dpx * dcx + dpy * dcy + r * dr
float B = dot(dp, diff);
float C = pow(dp.x, 2) + pow(dp.y, 2) - pow(radius1, 2);
float t = 0.5 * C / B;
// Addressing mode bug work-around.. first let's see if we should consider odd repetitions separately.
float oddeven = abs(fmod(floor(t), 2)) * allow_odd;
// Now let's calculate even or odd addressing in a branchless manner.
float t_repeated = ((t - floor(t)) * (1.0f - oddeven)) + ((ceil(t) - t) * oddeven);
float4 output = GradientTexture.Sample(GradientSampler, float2(t * (1.0f - repeat_correct) + t_repeated * repeat_correct, 0.5));
// Premultiply
output.rgb *= output.a;
// Multiply the output color by the input mask for the operation.
output *= InputTexture.Sample(InputSampler, texelSpaceInput0.xy);
// In order to compile for PS_4_0_level_9_3 we need to be branchless.
// This is essentially returning nothing, i.e. bailing early if:
// -radius1 >= t * diff.z
return output * abs(step(t * diff.z, -radius1) - 1.0f);
};
|
