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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 "Debug.h"
#include "Matrix.h"
#include "VertexBuffer.h"
namespace android {
namespace uirenderer {
// 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.
// Also, we need to add the centroid "12" to draw the umbra area as triangle fans.
//
// Triange strip indices for penumbra area: (0, 6, 1, 7, 2, 8, 3, 9, 4, 10, 5, 11, 0, 6)
// Triange strip indices for numbra area: (6, 12, 7, 12, 8, 12, 9, 12, 10, 12, 11, 12, 6)
// 0
//
// 5 6 1
// 11 7
// 12
// 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 256
// The total number of layers in the outer shadow area, 1 being the minimum.
#define SHADOW_LAYER_COUNT 2
// The total number of all the vertices representing the shadow.
#define SHADOW_VERTEX_COUNT ((SHADOW_LAYER_COUNT + 1) * SHADOW_RAY_COUNT + 1)
// The total number of indices used for drawing the shadow geometry as triangle strips.
#define SHADOW_INDEX_COUNT (2 * SHADOW_RAY_COUNT + 1 + 2 * (SHADOW_RAY_COUNT + 1) * \
SHADOW_LAYER_COUNT)
class ShadowTessellator {
public:
static void tessellateAmbientShadow(const Vector3* casterPolygon,
int casterVertexCount, const Vector3& centroid3d,
VertexBuffer& shadowVertexBuffer);
static void tessellateSpotShadow(const Vector3* casterPolygon, int casterVertexCount,
const Vector3& lightPosScale, const mat4& receiverTransform,
int screenWidth, int screenHeight, VertexBuffer& shadowVertexBuffer);
static void generateShadowIndices(uint16_t* shadowIndices);
static Vector2 centroid2d(const Vector2* poly, int polyLength);
}; // ShadowTessellator
}; // namespace uirenderer
}; // namespace android
#endif // ANDROID_HWUI_SHADOW_TESSELLATOR_H