118 lines
4.6 KiB
HLSL
118 lines
4.6 KiB
HLSL
/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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Texture2D InputTexture : register(t0);
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SamplerState InputSampler : register(s0);
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Texture2D GradientTexture : register(t1);
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SamplerState GradientSampler : register(s1);
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cbuffer constants : register(b0)
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{
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// Precalculate as much as we can!
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float3 diff : packoffset(c0.x);
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float2 center1 : packoffset(c1.x);
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float A : packoffset(c1.z);
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float radius1 : packoffset(c1.w);
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float sq_radius1 : packoffset(c2.x);
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// The next two values are used for a hack to compensate for an apparent
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// bug in D2D where the GradientSampler SamplerState doesn't get the
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// correct addressing modes.
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float repeat_correct : packoffset(c2.y);
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float allow_odd : packoffset(c2.z);
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float3x2 transform : packoffset(c3.x);
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}
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float4 SampleRadialGradientPS(
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float4 clipSpaceOutput : SV_POSITION,
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float4 sceneSpaceOutput : SCENE_POSITION,
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float4 texelSpaceInput0 : TEXCOORD0
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) : SV_Target
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{
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// Radial gradient painting is defined as the set of circles whose centers
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// are described by C(t) = (C2 - C1) * t + C1; with radii
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// R(t) = (R2 - R1) * t + R1; for R(t) > 0. This shader solves the
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// quadratic equation that arises when calculating t for pixel (x, y).
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//
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// A more extensive derrivation can be found in the pixman radial gradient
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// code.
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float2 p = float2(sceneSpaceOutput.x * transform._11 + sceneSpaceOutput.y * transform._21 + transform._31,
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sceneSpaceOutput.x * transform._12 + sceneSpaceOutput.y * transform._22 + transform._32);
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float3 dp = float3(p - center1, radius1);
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// dpx * dcx + dpy * dcy + r * dr
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float B = dot(dp, diff);
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float C = pow(dp.x, 2) + pow(dp.y, 2) - sq_radius1;
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float det = pow(B, 2) - A * C;
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float sqrt_det = sqrt(abs(det));
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float2 t = (B + float2(sqrt_det, -sqrt_det)) / A;
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float2 isValid = step(float2(-radius1, -radius1), t * diff.z);
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float upper_t = lerp(t.y, t.x, isValid.x);
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// Addressing mode bug work-around.. first let's see if we should consider odd repetitions separately.
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float oddeven = abs(fmod(floor(upper_t), 2)) * allow_odd;
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// Now let's calculate even or odd addressing in a branchless manner.
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float upper_t_repeated = ((upper_t - floor(upper_t)) * (1.0f - oddeven)) + ((ceil(upper_t) - upper_t) * oddeven);
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float4 output = GradientTexture.Sample(GradientSampler, float2(upper_t * (1.0f - repeat_correct) + upper_t_repeated * repeat_correct, 0.5));
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// Premultiply
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output.rgb *= output.a;
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// Multiply the output color by the input mask for the operation.
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output *= InputTexture.Sample(InputSampler, texelSpaceInput0.xy);
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// In order to compile for PS_4_0_level_9_3 we need to be branchless.
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// This is essentially returning nothing, i.e. bailing early if:
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// det < 0 || max(isValid.x, isValid.y) <= 0
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return output * abs(step(max(isValid.x, isValid.y), 0) - 1.0f) * step(0, det);
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};
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float4 SampleRadialGradientA0PS(
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float4 clipSpaceOutput : SV_POSITION,
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float4 sceneSpaceOutput : SCENE_POSITION,
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float4 texelSpaceInput0 : TEXCOORD0
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) : SV_Target
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{
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// This simpler shader is used for the degenerate case where A is 0,
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// i.e. we're actually solving a linear equation.
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float2 p = float2(sceneSpaceOutput.x * transform._11 + sceneSpaceOutput.y * transform._21 + transform._31,
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sceneSpaceOutput.x * transform._12 + sceneSpaceOutput.y * transform._22 + transform._32);
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float3 dp = float3(p - center1, radius1);
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// dpx * dcx + dpy * dcy + r * dr
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float B = dot(dp, diff);
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float C = pow(dp.x, 2) + pow(dp.y, 2) - pow(radius1, 2);
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float t = 0.5 * C / B;
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// Addressing mode bug work-around.. first let's see if we should consider odd repetitions separately.
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float oddeven = abs(fmod(floor(t), 2)) * allow_odd;
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// Now let's calculate even or odd addressing in a branchless manner.
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float t_repeated = ((t - floor(t)) * (1.0f - oddeven)) + ((ceil(t) - t) * oddeven);
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float4 output = GradientTexture.Sample(GradientSampler, float2(t * (1.0f - repeat_correct) + t_repeated * repeat_correct, 0.5));
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// Premultiply
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output.rgb *= output.a;
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// Multiply the output color by the input mask for the operation.
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output *= InputTexture.Sample(InputSampler, texelSpaceInput0.xy);
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// In order to compile for PS_4_0_level_9_3 we need to be branchless.
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// This is essentially returning nothing, i.e. bailing early if:
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// -radius1 >= t * diff.z
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return output * abs(step(t * diff.z, -radius1) - 1.0f);
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};
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