AmbientShadow.cpp revision 50ecf849cb7ccc3482517b74d2214b347927791e
155bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui/* 255bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * Copyright (C) 2013 The Android Open Source Project 355bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * 455bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * Licensed under the Apache License, Version 2.0 (the "License"); 555bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * you may not use this file except in compliance with the License. 655bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * You may obtain a copy of the License at 755bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * 855bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * http://www.apache.org/licenses/LICENSE-2.0 955bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * 1055bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * Unless required by applicable law or agreed to in writing, software 1155bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * distributed under the License is distributed on an "AS IS" BASIS, 1255bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 1355bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * See the License for the specific language governing permissions and 1455bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * limitations under the License. 1555bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui */ 1655bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui 1755bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui#define LOG_TAG "OpenGLRenderer" 1855bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui 1955bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui#include <math.h> 2055bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui#include <utils/Log.h> 21564acf7c9bff822f608cda0d5df0a64a9f9aaefdChris Craik#include <utils/Vector.h> 2255bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui 2355bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui#include "AmbientShadow.h" 2463d41abb40b3ce40d8b9bccb1cf186e8158a3687ztenghui#include "ShadowTessellator.h" 2555bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui#include "Vertex.h" 2655bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui 2755bfb4e728fe1db619af5d2c287f4abe711b3343ztenghuinamespace android { 2855bfb4e728fe1db619af5d2c287f4abe711b3343ztenghuinamespace uirenderer { 2955bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui 3055bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui/** 3155bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * Calculate the shadows as a triangle strips while alpha value as the 3255bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * shadow values. 3355bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * 3450ecf849cb7ccc3482517b74d2214b347927791eztenghui * @param isCasterOpaque Whether the caster is opaque. 3555bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * @param vertices The shadow caster's polygon, which is represented in a Vector3 3655bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * array. 3755bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * @param vertexCount The length of caster's polygon in terms of number of 3855bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * vertices. 3963d41abb40b3ce40d8b9bccb1cf186e8158a3687ztenghui * @param centroid3d The centroid of the shadow caster. 4055bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * @param heightFactor The factor showing the higher the object, the lighter the 4155bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * shadow. 4255bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * @param geomFactor The factor scaling the geometry expansion along the normal. 4355bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * 4455bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * @param shadowVertexBuffer Return an floating point array of (x, y, a) 4555bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * triangle strips mode. 4655bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui */ 4750ecf849cb7ccc3482517b74d2214b347927791eztenghuiVertexBufferMode AmbientShadow::createAmbientShadow(bool isCasterOpaque, 4850ecf849cb7ccc3482517b74d2214b347927791eztenghui const Vector3* vertices, int vertexCount, const Vector3& centroid3d, 4950ecf849cb7ccc3482517b74d2214b347927791eztenghui float heightFactor, float geomFactor, VertexBuffer& shadowVertexBuffer) { 5063d41abb40b3ce40d8b9bccb1cf186e8158a3687ztenghui const int rays = SHADOW_RAY_COUNT; 5150ecf849cb7ccc3482517b74d2214b347927791eztenghui VertexBufferMode mode = kVertexBufferMode_OnePolyRingShadow; 5255bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui // Validate the inputs. 53726118b35240957710d4d85fb5747e2ba8b934f7Chris Craik if (vertexCount < 3 || heightFactor <= 0 || rays <= 0 5455bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui || geomFactor <= 0) { 5555bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui#if DEBUG_SHADOW 5650ecf849cb7ccc3482517b74d2214b347927791eztenghui ALOGW("Invalid input for createAmbientShadow(), early return!"); 5755bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui#endif 5850ecf849cb7ccc3482517b74d2214b347927791eztenghui return mode; // vertex buffer is empty, so any mode doesn't matter. 5955bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui } 6055bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui 61564acf7c9bff822f608cda0d5df0a64a9f9aaefdChris Craik Vector<Vector2> dir; // TODO: use C++11 unique_ptr 62564acf7c9bff822f608cda0d5df0a64a9f9aaefdChris Craik dir.setCapacity(rays); 6355bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui float rayDist[rays]; 6455bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui float rayHeight[rays]; 65564acf7c9bff822f608cda0d5df0a64a9f9aaefdChris Craik calculateRayDirections(rays, dir.editArray()); 6655bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui 6755bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui // Calculate the length and height of the points along the edge. 6855bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui // 6955bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui // The math here is: 7055bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui // Intersect each ray (starting from the centroid) with the polygon. 7155bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui for (int i = 0; i < rays; i++) { 7255bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui int edgeIndex; 7355bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui float edgeFraction; 7455bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui float rayDistance; 7563d41abb40b3ce40d8b9bccb1cf186e8158a3687ztenghui calculateIntersection(vertices, vertexCount, centroid3d, dir[i], edgeIndex, 7655bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui edgeFraction, rayDistance); 7755bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui rayDist[i] = rayDistance; 7855bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui if (edgeIndex < 0 || edgeIndex >= vertexCount) { 7955bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui#if DEBUG_SHADOW 8050ecf849cb7ccc3482517b74d2214b347927791eztenghui ALOGW("Invalid edgeIndex!"); 8155bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui#endif 8255bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui edgeIndex = 0; 8355bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui } 8455bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui float h1 = vertices[edgeIndex].z; 8555bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui float h2 = vertices[((edgeIndex + 1) % vertexCount)].z; 8655bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui rayHeight[i] = h1 + edgeFraction * (h2 - h1); 8755bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui } 8855bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui 8955bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui // The output buffer length basically is roughly rays * layers, but since we 9055bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui // need triangle strips, so we need to duplicate vertices to accomplish that. 9150ecf849cb7ccc3482517b74d2214b347927791eztenghui AlphaVertex* shadowVertices = 9250ecf849cb7ccc3482517b74d2214b347927791eztenghui shadowVertexBuffer.alloc<AlphaVertex>(SHADOW_VERTEX_COUNT); 9355bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui 9455bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui // Calculate the vertex of the shadows. 9555bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui // 9655bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui // The math here is: 9755bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui // Along the edges of the polygon, for each intersection point P (generated above), 9855bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui // calculate the normal N, which should be perpendicular to the edge of the 9955bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui // polygon (represented by the neighbor intersection points) . 10055bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui // Shadow's vertices will be generated as : P + N * scale. 10150ecf849cb7ccc3482517b74d2214b347927791eztenghui const Vector2 centroid2d = Vector2(centroid3d.x, centroid3d.y); 102726118b35240957710d4d85fb5747e2ba8b934f7Chris Craik for (int rayIndex = 0; rayIndex < rays; rayIndex++) { 103726118b35240957710d4d85fb5747e2ba8b934f7Chris Craik Vector2 normal(1.0f, 0.0f); 104726118b35240957710d4d85fb5747e2ba8b934f7Chris Craik calculateNormal(rays, rayIndex, dir.array(), rayDist, normal); 10555bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui 106726118b35240957710d4d85fb5747e2ba8b934f7Chris Craik // The vertex should be start from rayDist[i] then scale the 107726118b35240957710d4d85fb5747e2ba8b934f7Chris Craik // normalizeNormal! 108726118b35240957710d4d85fb5747e2ba8b934f7Chris Craik Vector2 intersection = dir[rayIndex] * rayDist[rayIndex] + 10950ecf849cb7ccc3482517b74d2214b347927791eztenghui centroid2d; 11055bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui 111726118b35240957710d4d85fb5747e2ba8b934f7Chris Craik // outer ring of points, expanded based upon height of each ray intersection 112726118b35240957710d4d85fb5747e2ba8b934f7Chris Craik float expansionDist = rayHeight[rayIndex] * heightFactor * 113726118b35240957710d4d85fb5747e2ba8b934f7Chris Craik geomFactor; 114726118b35240957710d4d85fb5747e2ba8b934f7Chris Craik AlphaVertex::set(&shadowVertices[rayIndex], 115726118b35240957710d4d85fb5747e2ba8b934f7Chris Craik intersection.x + normal.x * expansionDist, 116726118b35240957710d4d85fb5747e2ba8b934f7Chris Craik intersection.y + normal.y * expansionDist, 117726118b35240957710d4d85fb5747e2ba8b934f7Chris Craik 0.0f); 11855bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui 119726118b35240957710d4d85fb5747e2ba8b934f7Chris Craik // inner ring of points 120726118b35240957710d4d85fb5747e2ba8b934f7Chris Craik float opacity = 1.0 / (1 + rayHeight[rayIndex] * heightFactor); 12150ecf849cb7ccc3482517b74d2214b347927791eztenghui AlphaVertex::set(&shadowVertices[rays + rayIndex], 122726118b35240957710d4d85fb5747e2ba8b934f7Chris Craik intersection.x, 123726118b35240957710d4d85fb5747e2ba8b934f7Chris Craik intersection.y, 124726118b35240957710d4d85fb5747e2ba8b934f7Chris Craik opacity); 12555bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui } 12655bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui 12750ecf849cb7ccc3482517b74d2214b347927791eztenghui // If caster isn't opaque, we need to to fill the umbra by storing the umbra's 12850ecf849cb7ccc3482517b74d2214b347927791eztenghui // centroid in the innermost ring of vertices. 12950ecf849cb7ccc3482517b74d2214b347927791eztenghui if (!isCasterOpaque) { 13050ecf849cb7ccc3482517b74d2214b347927791eztenghui mode = kVertexBufferMode_TwoPolyRingShadow; 13150ecf849cb7ccc3482517b74d2214b347927791eztenghui float centroidAlpha = 1.0 / (1 + centroid3d.z * heightFactor); 13250ecf849cb7ccc3482517b74d2214b347927791eztenghui AlphaVertex centroidXYA; 13350ecf849cb7ccc3482517b74d2214b347927791eztenghui AlphaVertex::set(¢roidXYA, centroid2d.x, centroid2d.y, centroidAlpha); 13450ecf849cb7ccc3482517b74d2214b347927791eztenghui for (int rayIndex = 0; rayIndex < rays; rayIndex++) { 13550ecf849cb7ccc3482517b74d2214b347927791eztenghui shadowVertices[2 * rays + rayIndex] = centroidXYA; 13650ecf849cb7ccc3482517b74d2214b347927791eztenghui } 13755bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui } 13850ecf849cb7ccc3482517b74d2214b347927791eztenghui 13950ecf849cb7ccc3482517b74d2214b347927791eztenghui#if DEBUG_SHADOW 14063d41abb40b3ce40d8b9bccb1cf186e8158a3687ztenghui for (int i = 0; i < SHADOW_VERTEX_COUNT; i++) { 14163d41abb40b3ce40d8b9bccb1cf186e8158a3687ztenghui ALOGD("ambient shadow value: i %d, (x:%f, y:%f, a:%f)", i, shadowVertices[i].x, 14263d41abb40b3ce40d8b9bccb1cf186e8158a3687ztenghui shadowVertices[i].y, shadowVertices[i].alpha); 14355bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui } 14455bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui#endif 14550ecf849cb7ccc3482517b74d2214b347927791eztenghui return mode; 14655bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui} 14755bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui 14855bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui/** 14955bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * Generate an array of rays' direction vectors. 15055bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * 15155bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * @param rays The number of rays shooting out from the centroid. 15255bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * @param dir Return the array of ray vectors. 15355bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui */ 15455bfb4e728fe1db619af5d2c287f4abe711b3343ztenghuivoid AmbientShadow::calculateRayDirections(int rays, Vector2* dir) { 15555bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui float deltaAngle = 2 * M_PI / rays; 15655bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui 15755bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui for (int i = 0; i < rays; i++) { 15855bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui dir[i].x = sinf(deltaAngle * i); 15955bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui dir[i].y = cosf(deltaAngle * i); 16055bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui } 16155bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui} 16255bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui 16355bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui/** 16455bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * Calculate the intersection of a ray hitting the polygon. 16555bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * 16655bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * @param vertices The shadow caster's polygon, which is represented in a 16755bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * Vector3 array. 16855bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * @param vertexCount The length of caster's polygon in terms of number of vertices. 16955bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * @param start The starting point of the ray. 17055bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * @param dir The direction vector of the ray. 17155bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * 17255bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * @param outEdgeIndex Return the index of the segment (or index of the starting 17355bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * vertex) that ray intersect with. 17455bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * @param outEdgeFraction Return the fraction offset from the segment starting 17555bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * index. 17655bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * @param outRayDist Return the ray distance from centroid to the intersection. 17755bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui */ 17855bfb4e728fe1db619af5d2c287f4abe711b3343ztenghuivoid AmbientShadow::calculateIntersection(const Vector3* vertices, int vertexCount, 17963d41abb40b3ce40d8b9bccb1cf186e8158a3687ztenghui const Vector3& start, const Vector2& dir, int& outEdgeIndex, 18055bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui float& outEdgeFraction, float& outRayDist) { 18155bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui float startX = start.x; 18255bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui float startY = start.y; 18355bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui float dirX = dir.x; 18455bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui float dirY = dir.y; 18555bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui // Start the search from the last edge from poly[len-1] to poly[0]. 18655bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui int p1 = vertexCount - 1; 18755bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui 18855bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui for (int p2 = 0; p2 < vertexCount; p2++) { 18955bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui float p1x = vertices[p1].x; 19055bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui float p1y = vertices[p1].y; 19155bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui float p2x = vertices[p2].x; 19255bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui float p2y = vertices[p2].y; 19355bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui 19455bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui // The math here is derived from: 19555bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui // f(t, v) = p1x * (1 - t) + p2x * t - (startX + dirX * v) = 0; 19655bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui // g(t, v) = p1y * (1 - t) + p2y * t - (startY + dirY * v) = 0; 19755bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui float div = (dirX * (p1y - p2y) + dirY * p2x - dirY * p1x); 19855bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui if (div != 0) { 19955bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui float t = (dirX * (p1y - startY) + dirY * startX - dirY * p1x) / (div); 20055bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui if (t > 0 && t <= 1) { 20155bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui float t2 = (p1x * (startY - p2y) 20255bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui + p2x * (p1y - startY) 20355bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui + startX * (p2y - p1y)) / div; 20455bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui if (t2 > 0) { 20555bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui outEdgeIndex = p1; 20655bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui outRayDist = t2; 20755bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui outEdgeFraction = t; 20855bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui return; 20955bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui } 21055bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui } 21155bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui } 21255bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui p1 = p2; 21355bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui } 21455bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui return; 21555bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui}; 21655bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui 21755bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui/** 21855bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * Calculate the normal at the intersection point between a ray and the polygon. 21955bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * 22055bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * @param rays The total number of rays. 22155bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * @param currentRayIndex The index of the ray which the normal is based on. 22255bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * @param dir The array of the all the rays directions. 22355bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * @param rayDist The pre-computed ray distances array. 22455bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * 22555bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui * @param normal Return the normal. 22655bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui */ 22755bfb4e728fe1db619af5d2c287f4abe711b3343ztenghuivoid AmbientShadow::calculateNormal(int rays, int currentRayIndex, 22855bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui const Vector2* dir, const float* rayDist, Vector2& normal) { 22955bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui int preIndex = (currentRayIndex - 1 + rays) % rays; 23055bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui int postIndex = (currentRayIndex + 1) % rays; 23155bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui Vector2 p1 = dir[preIndex] * rayDist[preIndex]; 23255bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui Vector2 p2 = dir[postIndex] * rayDist[postIndex]; 23355bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui 23455bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui // Now the V (deltaX, deltaY) is the vector going CW around the poly. 23555bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui Vector2 delta = p2 - p1; 23655bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui if (delta.length() != 0) { 23755bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui delta.normalize(); 23855bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui // Calculate the normal , which is CCW 90 rotate to the V. 23955bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui // 90 degrees CCW about z-axis: (x, y, z) -> (-y, x, z) 24055bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui normal.x = -delta.y; 24155bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui normal.y = delta.x; 24255bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui } 24355bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui} 24455bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui 24555bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui}; // namespace uirenderer 24655bfb4e728fe1db619af5d2c287f4abe711b3343ztenghui}; // namespace android 247