1 files changed, 117 insertions, 0 deletions
diff --git a/gfx/2d/ShadersD2D1.hlsl b/gfx/2d/ShadersD2D1.hlsl
new file mode 100644
index 000000000..42337afc2
--- /dev/null
+++ b/gfx/2d/ShadersD2D1.hlsl
@@ -0,0 +1,117 @@
+/* -*- 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);
+};
+