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/*
* Copyright 2017 Google Inc. All Rights Reserved.
*
* 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.
*/
#include "plane_renderer.h"
#include "util.h"
namespace hello_ar {
namespace {
constexpr char kVertexShader[] = R"(
precision highp float;
precision highp int;
attribute vec3 vertex;
varying vec2 v_textureCoords;
varying float v_alpha;
uniform mat4 mvp;
uniform mat4 model_mat;
uniform vec3 normal;
void main() {
// Vertex Z value is used as the alpha in this shader.
v_alpha = vertex.z;
vec4 local_pos = vec4(vertex.x, 0.0, vertex.y, 1.0);
gl_Position = mvp * local_pos;
vec4 world_pos = model_mat * local_pos;
// Construct two vectors that are orthogonal to the normal.
// This arbitrary choice is not co-linear with either horizontal
// or vertical plane normals.
const vec3 arbitrary = vec3(1.0, 1.0, 0.0);
vec3 vec_u = normalize(cross(normal, arbitrary));
vec3 vec_v = normalize(cross(normal, vec_u));
// Project vertices in world frame onto vec_u and vec_v.
v_textureCoords = vec2(
dot(world_pos.xyz, vec_u), dot(world_pos.xyz, vec_v));
})";
constexpr char kFragmentShader[] = R"(
precision highp float;
precision highp int;
uniform sampler2D texture;
uniform vec3 color;
varying vec2 v_textureCoords;
varying float v_alpha;
void main() {
float r = texture2D(texture, v_textureCoords).r;
gl_FragColor = vec4(color.xyz, r * v_alpha);
})";
} // namespace
void PlaneRenderer::InitializeGlContent(AAssetManager *asset_manager) {
shader_program_ = util::CreateProgram(kVertexShader, kFragmentShader);
if (!shader_program_) {
LOGE("Could not create program.");
}
uniform_mvp_mat_ = glGetUniformLocation(shader_program_, "mvp");
uniform_texture_ = glGetUniformLocation(shader_program_, "texture");
uniform_model_mat_ = glGetUniformLocation(shader_program_, "model_mat");
uniform_normal_vec_ = glGetUniformLocation(shader_program_, "normal");
uniform_color_ = glGetUniformLocation(shader_program_, "color");
attri_vertices_ = glGetAttribLocation(shader_program_, "vertex");
glGenTextures(1, &texture_id_);
glBindTexture(GL_TEXTURE_2D, texture_id_);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
GL_LINEAR_MIPMAP_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
if (!util::LoadPngFromAssetManager(GL_TEXTURE_2D, "models/trigrid.png")) {
LOGE("Could not load png texture for planes.");
}
glGenerateMipmap(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, 0);
util::CheckGlError("plane_renderer::InitializeGlContent()");
}
void PlaneRenderer::Draw(const glm::mat4 &projection_mat,
const glm::mat4 &view_mat, const ArSession *ar_session,
const ArPlane *ar_plane, const glm::vec3 &color) {
if (!shader_program_) {
LOGE("shader_program is null.");
return;
}
UpdateForPlane(ar_session, ar_plane);
glUseProgram(shader_program_);
glDepthMask(GL_FALSE);
glActiveTexture(GL_TEXTURE0);
glUniform1i(uniform_texture_, 0);
glBindTexture(GL_TEXTURE_2D, texture_id_);
// Compose final mvp matrix for this plane renderer.
glUniformMatrix4fv(uniform_mvp_mat_, 1, GL_FALSE,
glm::value_ptr(projection_mat * view_mat * model_mat_));
glUniformMatrix4fv(uniform_model_mat_, 1, GL_FALSE,
glm::value_ptr(model_mat_));
glUniform3f(uniform_normal_vec_, normal_vec_.x, normal_vec_.y, normal_vec_.z);
glUniform3f(uniform_color_, color.x, color.y, color.z);
glEnableVertexAttribArray(attri_vertices_);
glVertexAttribPointer(attri_vertices_, 3, GL_FLOAT, GL_FALSE, 0,
vertices_.data());
glDrawElements(GL_TRIANGLES, triangles_.size(), GL_UNSIGNED_SHORT,
triangles_.data());
glUseProgram(0);
glDepthMask(GL_TRUE);
util::CheckGlError("plane_renderer::Draw()");
}
void PlaneRenderer::UpdateForPlane(const ArSession *ar_session,
const ArPlane *ar_plane) {
// The following code generates a triangle mesh filling a convex polygon,
// including a feathered edge for blending.
//
// The indices shown in the diagram are used in comments below.
// _______________ 0_______________1
// | | |4___________5|
// | | | | | |
// | | => | | | |
// | | | | | |
// | | |7-----------6|
// --------------- 3---------------2
vertices_.clear();
triangles_.clear();
int32_t polygon_length;
ArPlane_getPolygonSize(ar_session, ar_plane, &polygon_length);
if (polygon_length == 0) {
LOGE("PlaneRenderer::UpdatePlane, no valid plane polygon is found");
return;
}
const int32_t vertices_size = polygon_length / 2;
std::vector<glm::vec2> raw_vertices(vertices_size);
ArPlane_getPolygon(ar_session, ar_plane,
glm::value_ptr(raw_vertices.front()));
// Fill vertex 0 to 3. Note that the vertex.xy are used for x and z
// position. vertex.z is used for alpha. The outter polygon's alpha
// is 0.
for (int32_t i = 0; i < vertices_size; ++i) {
vertices_.push_back(glm::vec3(raw_vertices[i].x, raw_vertices[i].y, 0.0f));
}
util::ScopedArPose scopedArPose(ar_session);
ArPlane_getCenterPose(ar_session, ar_plane, scopedArPose.GetArPose());
ArPose_getMatrix(ar_session, scopedArPose.GetArPose(),
glm::value_ptr(model_mat_));
normal_vec_ = util::GetPlaneNormal(ar_session, *scopedArPose.GetArPose());
// Feather distance 0.2 meters.
const float kFeatherLength = 0.2f;
// Feather scale over the distance between plane center and vertices.
const float kFeatherScale = 0.2f;
// Fill vertex 4 to 7, with alpha set to 1.
for (int32_t i = 0; i < vertices_size; ++i) {
// Vector from plane center to current point.
glm::vec2 v = raw_vertices[i];
const float scale =
1.0f - std::min((kFeatherLength / glm::length(v)), kFeatherScale);
const glm::vec2 result_v = scale * v;
vertices_.push_back(glm::vec3(result_v.x, result_v.y, 1.0f));
}
const int32_t vertices_length = vertices_.size();
const int32_t half_vertices_length = vertices_length / 2;
// Generate triangle (4, 5, 6) and (4, 6, 7).
for (int i = half_vertices_length + 1; i < vertices_length - 1; ++i) {
triangles_.push_back(half_vertices_length);
triangles_.push_back(i);
triangles_.push_back(i + 1);
}
// Generate triangle (0, 1, 4), (4, 1, 5), (5, 1, 2), (5, 2, 6),
// (6, 2, 3), (6, 3, 7), (7, 3, 0), (7, 0, 4)
for (int i = 0; i < half_vertices_length; ++i) {
triangles_.push_back(i);
triangles_.push_back((i + 1) % half_vertices_length);
triangles_.push_back(i + half_vertices_length);
triangles_.push_back(i + half_vertices_length);
triangles_.push_back((i + 1) % half_vertices_length);
triangles_.push_back((i + half_vertices_length + 1) % half_vertices_length +
half_vertices_length);
}
}
} // namespace hello_ar
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