1 // Copyright 2018 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "device/vr/android/arcore/ar_renderer.h"
6
7 #include "base/stl_util.h"
8 #include "device/vr/vr_gl_util.h"
9
10 namespace device {
11
12 namespace {
13
14 static constexpr float kQuadVertices[8] = {
15 -0.5f, 0.5f, -0.5f, -0.5f, 0.5f, 0.5f, 0.5f, -0.5f,
16 };
17 static constexpr GLushort kQuadIndices[6] = {0, 1, 2, 1, 3, 2};
18
19 // clang-format off
20 static constexpr char const* kVertexShader = SHADER(
21 precision mediump float;
22 uniform mat4 u_UvTransform;
23 attribute vec4 a_Position;
24 varying vec2 v_TexCoordinate;
25
26 void main() {
27 // The quad vertex coordinate range is [-0.5, 0.5]. Transform to [0, 1],
28 // then apply the supplied affine transform matrix to get the final UV.
29 float xposition = a_Position[0] + 0.5;
30 float yposition = a_Position[1] + 0.5;
31 vec4 uv_in = vec4(xposition, yposition, 0.0, 1.0);
32 vec4 uv_out = u_UvTransform * uv_in;
33 v_TexCoordinate = vec2(uv_out.x, uv_out.y);
34 gl_Position = vec4(a_Position.xyz * 2.0, 1.0);
35 }
36 );
37
38 static constexpr char const* kFragmentShader = OEIE_SHADER(
39 precision highp float;
40 uniform samplerExternalOES u_Texture;
41 varying vec2 v_TexCoordinate;
42
43 void main() {
44 gl_FragColor = texture2D(u_Texture, v_TexCoordinate);
45 }
46 );
47 // clang-format on
48
49 } // namespace
50
ArRenderer()51 ArRenderer::ArRenderer() {
52 std::string error;
53 GLuint vertex_shader_handle =
54 vr::CompileShader(GL_VERTEX_SHADER, kVertexShader, error);
55 // TODO(crbug.com/866593): fail gracefully if shaders don't compile.
56 CHECK(vertex_shader_handle) << error << "\nvertex_src\n" << kVertexShader;
57
58 GLuint fragment_shader_handle =
59 vr::CompileShader(GL_FRAGMENT_SHADER, kFragmentShader, error);
60 CHECK(fragment_shader_handle) << error << "\nfragment_src\n"
61 << kFragmentShader;
62
63 program_handle_ = vr::CreateAndLinkProgram(vertex_shader_handle,
64 fragment_shader_handle, error);
65 CHECK(program_handle_) << error;
66
67 // Once the program is linked the shader objects are no longer needed
68 glDeleteShader(vertex_shader_handle);
69 glDeleteShader(fragment_shader_handle);
70
71 position_handle_ = glGetAttribLocation(program_handle_, "a_Position");
72 clip_rect_handle_ = glGetUniformLocation(program_handle_, "u_ClipRect");
73 texture_handle_ = glGetUniformLocation(program_handle_, "u_Texture");
74 uv_transform_ = glGetUniformLocation(program_handle_, "u_UvTransform");
75 }
76
Draw(int texture_handle,const float (& uv_transform)[16])77 void ArRenderer::Draw(int texture_handle, const float (&uv_transform)[16]) {
78 if (!vertex_buffer_ || !index_buffer_) {
79 GLuint buffers[2];
80 glGenBuffersARB(2, buffers);
81 vertex_buffer_ = buffers[0];
82 index_buffer_ = buffers[1];
83
84 glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer_);
85 glBufferData(GL_ARRAY_BUFFER, base::size(kQuadVertices) * sizeof(float),
86 kQuadVertices, GL_STATIC_DRAW);
87
88 glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, index_buffer_);
89 glBufferData(GL_ELEMENT_ARRAY_BUFFER,
90 base::size(kQuadIndices) * sizeof(GLushort), kQuadIndices,
91 GL_STATIC_DRAW);
92 }
93
94 glUseProgram(program_handle_);
95
96 // Bind vertex attributes
97 glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer_);
98
99 // Set up position attribute.
100 glVertexAttribPointer(position_handle_, 2, GL_FLOAT, false, 0, 0);
101 glEnableVertexAttribArray(position_handle_);
102
103 // Bind texture. This is not necessarily a 1:1 pixel copy since the
104 // size is modified by framebufferScaleFactor and requestViewportScale,
105 // so use GL_LINEAR.
106 glActiveTexture(GL_TEXTURE0);
107 glBindTexture(GL_TEXTURE_EXTERNAL_OES, texture_handle);
108 glTexParameteri(GL_TEXTURE_EXTERNAL_OES, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
109 glTexParameteri(GL_TEXTURE_EXTERNAL_OES, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
110 glTexParameteri(GL_TEXTURE_EXTERNAL_OES, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
111 glTexParameteri(GL_TEXTURE_EXTERNAL_OES, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
112 glUniform1i(texture_handle_, 0);
113
114 glUniformMatrix4fv(uv_transform_, 1, GL_FALSE, &uv_transform[0]);
115
116 // Blit texture to buffer
117 glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, index_buffer_);
118 glDrawElements(GL_TRIANGLES, base::size(kQuadIndices), GL_UNSIGNED_SHORT, 0);
119
120 glDisableVertexAttribArray(position_handle_);
121 }
122
123 // Note that we don't explicitly delete gl objects here, they're deleted
124 // automatically when we call ShutdownGL, and deleting them here leads to
125 // segfaults.
126 ArRenderer::~ArRenderer() = default;
127
128 } // namespace device
129