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/*
* Copyright (C) 2013 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef ANDROID_HWUI_SHADOW_TESSELLATOR_H
#define ANDROID_HWUI_SHADOW_TESSELLATOR_H
#include <SkPath.h>
#include "Debug.h"
#include "Matrix.h"
namespace android {
namespace uirenderer {
class VertexBuffer;
// All SHADOW_* are used to define all the geometry property of shadows.
// Use a simplified example to illustrate the geometry setup here.
// Assuming we use 6 rays and only 1 layer, Then we will have 2 hexagons, which
// are 0 to 5 and 6 to 11. The area between them will be the penumbra area, and
// the area inside the 2nd hexagon is the umbra.
// Ambient shadow is using only 1 layer for opaque caster, otherwise, spot
// shadow and ambient shadow are using 2 layers.
// Triange strip indices for penumbra area: (0, 6, 1, 7, 2, 8, 3, 9, 4, 10, 5, 11, 0, 6)
// 0
//
// 5 6 1
// 11 7
//
// 10 8
// 4 9 2
//
// 3
// The total number of rays starting from the centroid of shadow area, in order
// to generate the shadow geometry.
#define SHADOW_RAY_COUNT 128
// The total number of all the vertices representing the shadow.
// For the case we only have 1 layer, then we will just fill only 2/3 of it.
#define SHADOW_VERTEX_COUNT (3 * SHADOW_RAY_COUNT)
// The total number of indices used for drawing the shadow geometry as triangle strips.
// Depending on the mode we are drawing, we can have 1 layer or 2 layers.
// Therefore, we only build the longer index buffer.
#define TWO_POLY_RING_SHADOW_INDEX_COUNT (4 * (SHADOW_RAY_COUNT + 1))
#define ONE_POLY_RING_SHADOW_INDEX_COUNT (2 * (SHADOW_RAY_COUNT + 1))
#define MAX_SHADOW_INDEX_COUNT TWO_POLY_RING_SHADOW_INDEX_COUNT
#define SHADOW_MIN_CASTER_Z 0.001f
#define MINIMAL_DELTA_THETA (M_PI / 180 / 1000)
class ShadowTessellator {
public:
static void tessellateAmbientShadow(bool isCasterOpaque,
const Vector3* casterPolygon, int casterVertexCount,
const Vector3& centroid3d, const Rect& casterBounds,
const Rect& localClip, float maxZ, VertexBuffer& shadowVertexBuffer);
static void tessellateSpotShadow(bool isCasterOpaque,
const Vector3* casterPolygon, int casterVertexCount, const Vector3& casterCentroid,
const mat4& receiverTransform, const Vector3& lightCenter, int lightRadius,
const Rect& casterBounds, const Rect& localClip, VertexBuffer& shadowVertexBuffer);
static Vector2 centroid2d(const Vector2* poly, int polyLength);
static bool isClockwise(const Vector2* polygon, int len);
static Vector2 calculateNormal(const Vector2& p1, const Vector2& p2);
static int getExtraVertexNumber(const Vector2& vector1, const Vector2& vector2,
float divisor);
static void checkOverflow(int used, int total, const char* bufferName);
}; // ShadowTessellator
}; // namespace uirenderer
}; // namespace android
#endif // ANDROID_HWUI_SHADOW_TESSELLATOR_H
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