1 // Copyright 2014 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 // This example program is based on Simple_VertexShader.c from:
6
7 //
8 // Book: OpenGL(R) ES 2.0 Programming Guide
9 // Authors: Aaftab Munshi, Dan Ginsburg, Dave Shreiner
10 // ISBN-10: 0321502795
11 // ISBN-13: 9780321502797
12 // Publisher: Addison-Wesley Professional
13 // URLs: http://safari.informit.com/9780321563835
14 // http://www.opengles-book.com
15 //
16
17 #include "ppapi/examples/compositor/spinning_cube.h"
18
19 #include <math.h>
20 #include <stdlib.h>
21 #include <string.h>
22
23 #include <algorithm>
24
25 #include "ppapi/lib/gl/include/GLES2/gl2.h"
26
27 namespace {
28
29 const float kPi = 3.14159265359f;
30
GenerateCube(GLuint * vbo_vertices,GLuint * vbo_indices)31 int GenerateCube(GLuint *vbo_vertices,
32 GLuint *vbo_indices) {
33 const int num_indices = 36;
34
35 const GLfloat cube_vertices[] = {
36 -0.5f, -0.5f, -0.5f,
37 0.5f, -0.5f, -0.5f,
38 0.5f, -0.5f, 0.5f,
39 -0.5f, -0.5f, 0.5f,
40 -0.5f, 0.5f, -0.5f,
41 0.5f, 0.5f, -0.5f,
42 0.5f, 0.5f, 0.5f,
43 -0.5f, 0.5f, 0.5f,
44 };
45
46 const GLushort cube_indices[] = {
47 0, 2, 1,
48 0, 3, 2,
49 4, 5, 6,
50 4, 6, 7,
51 3, 6, 2,
52 3, 7, 6,
53 0, 1, 5,
54 0, 5, 4,
55 0, 7, 3,
56 0, 4, 7,
57 1, 2, 6,
58 1, 6, 5,
59 };
60
61 if (vbo_vertices) {
62 glGenBuffers(1, vbo_vertices);
63 glBindBuffer(GL_ARRAY_BUFFER, *vbo_vertices);
64 glBufferData(GL_ARRAY_BUFFER,
65 sizeof(cube_vertices),
66 cube_vertices,
67 GL_STATIC_DRAW);
68 glBindBuffer(GL_ARRAY_BUFFER, 0);
69 }
70
71 if (vbo_indices) {
72 glGenBuffers(1, vbo_indices);
73 glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, *vbo_indices);
74 glBufferData(GL_ELEMENT_ARRAY_BUFFER,
75 sizeof(cube_indices),
76 cube_indices,
77 GL_STATIC_DRAW);
78 glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
79 }
80
81 return num_indices;
82 }
83
LoadShader(GLenum type,const char * shader_source)84 GLuint LoadShader(GLenum type,
85 const char* shader_source) {
86 GLuint shader = glCreateShader(type);
87 glShaderSource(shader, 1, &shader_source, NULL);
88 glCompileShader(shader);
89
90 GLint compiled = 0;
91 glGetShaderiv(shader, GL_COMPILE_STATUS, &compiled);
92
93 if (!compiled) {
94 glDeleteShader(shader);
95 return 0;
96 }
97
98 return shader;
99 }
100
LoadProgram(const char * vertext_shader_source,const char * fragment_shader_source)101 GLuint LoadProgram(const char* vertext_shader_source,
102 const char* fragment_shader_source) {
103 GLuint vertex_shader = LoadShader(GL_VERTEX_SHADER,
104 vertext_shader_source);
105 if (!vertex_shader)
106 return 0;
107
108 GLuint fragment_shader = LoadShader(GL_FRAGMENT_SHADER,
109 fragment_shader_source);
110 if (!fragment_shader) {
111 glDeleteShader(vertex_shader);
112 return 0;
113 }
114
115 GLuint program_object = glCreateProgram();
116 glAttachShader(program_object, vertex_shader);
117 glAttachShader(program_object, fragment_shader);
118
119 glLinkProgram(program_object);
120
121 glDeleteShader(vertex_shader);
122 glDeleteShader(fragment_shader);
123
124 GLint linked = 0;
125 glGetProgramiv(program_object, GL_LINK_STATUS, &linked);
126
127 if (!linked) {
128 glDeleteProgram(program_object);
129 return 0;
130 }
131
132 return program_object;
133 }
134
135 class ESMatrix {
136 public:
137 GLfloat m[4][4];
138
ESMatrix()139 ESMatrix() {
140 LoadZero();
141 }
142
LoadZero()143 void LoadZero() {
144 memset(this, 0x0, sizeof(ESMatrix));
145 }
146
LoadIdentity()147 void LoadIdentity() {
148 LoadZero();
149 m[0][0] = 1.0f;
150 m[1][1] = 1.0f;
151 m[2][2] = 1.0f;
152 m[3][3] = 1.0f;
153 }
154
Multiply(ESMatrix * a,ESMatrix * b)155 void Multiply(ESMatrix* a, ESMatrix* b) {
156 ESMatrix result;
157 for (int i = 0; i < 4; ++i) {
158 result.m[i][0] = (a->m[i][0] * b->m[0][0]) +
159 (a->m[i][1] * b->m[1][0]) +
160 (a->m[i][2] * b->m[2][0]) +
161 (a->m[i][3] * b->m[3][0]);
162
163 result.m[i][1] = (a->m[i][0] * b->m[0][1]) +
164 (a->m[i][1] * b->m[1][1]) +
165 (a->m[i][2] * b->m[2][1]) +
166 (a->m[i][3] * b->m[3][1]);
167
168 result.m[i][2] = (a->m[i][0] * b->m[0][2]) +
169 (a->m[i][1] * b->m[1][2]) +
170 (a->m[i][2] * b->m[2][2]) +
171 (a->m[i][3] * b->m[3][2]);
172
173 result.m[i][3] = (a->m[i][0] * b->m[0][3]) +
174 (a->m[i][1] * b->m[1][3]) +
175 (a->m[i][2] * b->m[2][3]) +
176 (a->m[i][3] * b->m[3][3]);
177 }
178 *this = result;
179 }
180
Frustum(float left,float right,float bottom,float top,float near_z,float far_z)181 void Frustum(float left,
182 float right,
183 float bottom,
184 float top,
185 float near_z,
186 float far_z) {
187 float delta_x = right - left;
188 float delta_y = top - bottom;
189 float delta_z = far_z - near_z;
190
191 if ((near_z <= 0.0f) ||
192 (far_z <= 0.0f) ||
193 (delta_z <= 0.0f) ||
194 (delta_y <= 0.0f) ||
195 (delta_y <= 0.0f))
196 return;
197
198 ESMatrix frust;
199 frust.m[0][0] = 2.0f * near_z / delta_x;
200 frust.m[0][1] = frust.m[0][2] = frust.m[0][3] = 0.0f;
201
202 frust.m[1][1] = 2.0f * near_z / delta_y;
203 frust.m[1][0] = frust.m[1][2] = frust.m[1][3] = 0.0f;
204
205 frust.m[2][0] = (right + left) / delta_x;
206 frust.m[2][1] = (top + bottom) / delta_y;
207 frust.m[2][2] = -(near_z + far_z) / delta_z;
208 frust.m[2][3] = -1.0f;
209
210 frust.m[3][2] = -2.0f * near_z * far_z / delta_z;
211 frust.m[3][0] = frust.m[3][1] = frust.m[3][3] = 0.0f;
212
213 Multiply(&frust, this);
214 }
215
Perspective(float fov_y,float aspect,float near_z,float far_z)216 void Perspective(float fov_y, float aspect, float near_z, float far_z) {
217 GLfloat frustum_h = tanf(fov_y / 360.0f * kPi) * near_z;
218 GLfloat frustum_w = frustum_h * aspect;
219 Frustum(-frustum_w, frustum_w, -frustum_h, frustum_h, near_z, far_z);
220 }
221
Translate(GLfloat tx,GLfloat ty,GLfloat tz)222 void Translate(GLfloat tx, GLfloat ty, GLfloat tz) {
223 m[3][0] += m[0][0] * tx + m[1][0] * ty + m[2][0] * tz;
224 m[3][1] += m[0][1] * tx + m[1][1] * ty + m[2][1] * tz;
225 m[3][2] += m[0][2] * tx + m[1][2] * ty + m[2][2] * tz;
226 m[3][3] += m[0][3] * tx + m[1][3] * ty + m[2][3] * tz;
227 }
228
Rotate(GLfloat angle,GLfloat x,GLfloat y,GLfloat z)229 void Rotate(GLfloat angle, GLfloat x, GLfloat y, GLfloat z) {
230 GLfloat mag = sqrtf(x * x + y * y + z * z);
231
232 GLfloat sin_angle = sinf(angle * kPi / 180.0f);
233 GLfloat cos_angle = cosf(angle * kPi / 180.0f);
234 if (mag > 0.0f) {
235 GLfloat xx, yy, zz, xy, yz, zx, xs, ys, zs;
236 GLfloat one_minus_cos;
237 ESMatrix rotation;
238
239 x /= mag;
240 y /= mag;
241 z /= mag;
242
243 xx = x * x;
244 yy = y * y;
245 zz = z * z;
246 xy = x * y;
247 yz = y * z;
248 zx = z * x;
249 xs = x * sin_angle;
250 ys = y * sin_angle;
251 zs = z * sin_angle;
252 one_minus_cos = 1.0f - cos_angle;
253
254 rotation.m[0][0] = (one_minus_cos * xx) + cos_angle;
255 rotation.m[0][1] = (one_minus_cos * xy) - zs;
256 rotation.m[0][2] = (one_minus_cos * zx) + ys;
257 rotation.m[0][3] = 0.0F;
258
259 rotation.m[1][0] = (one_minus_cos * xy) + zs;
260 rotation.m[1][1] = (one_minus_cos * yy) + cos_angle;
261 rotation.m[1][2] = (one_minus_cos * yz) - xs;
262 rotation.m[1][3] = 0.0F;
263
264 rotation.m[2][0] = (one_minus_cos * zx) - ys;
265 rotation.m[2][1] = (one_minus_cos * yz) + xs;
266 rotation.m[2][2] = (one_minus_cos * zz) + cos_angle;
267 rotation.m[2][3] = 0.0F;
268
269 rotation.m[3][0] = 0.0F;
270 rotation.m[3][1] = 0.0F;
271 rotation.m[3][2] = 0.0F;
272 rotation.m[3][3] = 1.0F;
273
274 Multiply(&rotation, this);
275 }
276 }
277 };
278
RotationForTimeDelta(float delta_time)279 float RotationForTimeDelta(float delta_time) {
280 return delta_time * 40.0f;
281 }
282
RotationForDragDistance(float drag_distance)283 float RotationForDragDistance(float drag_distance) {
284 return drag_distance / 5; // Arbitrary damping.
285 }
286
287 } // namespace
288
289 class SpinningCube::GLState {
290 public:
291 GLState();
292
293 void OnGLContextLost();
294
295 GLfloat angle_; // Survives losing the GL context.
296
297 GLuint program_object_;
298 GLint position_location_;
299 GLint mvp_location_;
300 GLuint vbo_vertices_;
301 GLuint vbo_indices_;
302 int num_indices_;
303 ESMatrix mvp_matrix_;
304 };
305
GLState()306 SpinningCube::GLState::GLState()
307 : angle_(0) {
308 OnGLContextLost();
309 }
310
OnGLContextLost()311 void SpinningCube::GLState::OnGLContextLost() {
312 program_object_ = 0;
313 position_location_ = 0;
314 mvp_location_ = 0;
315 vbo_vertices_ = 0;
316 vbo_indices_ = 0;
317 num_indices_ = 0;
318 }
319
SpinningCube()320 SpinningCube::SpinningCube()
321 : initialized_(false),
322 width_(0),
323 height_(0),
324 state_(new GLState()),
325 fling_multiplier_(1.0f),
326 direction_(1) {
327 state_->angle_ = 45.0f;
328 }
329
~SpinningCube()330 SpinningCube::~SpinningCube() {
331 if (!initialized_)
332 return;
333 if (state_->vbo_vertices_)
334 glDeleteBuffers(1, &state_->vbo_vertices_);
335 if (state_->vbo_indices_)
336 glDeleteBuffers(1, &state_->vbo_indices_);
337 if (state_->program_object_)
338 glDeleteProgram(state_->program_object_);
339
340 delete state_;
341 }
342
Init(uint32_t width,uint32_t height)343 void SpinningCube::Init(uint32_t width, uint32_t height) {
344 width_ = width;
345 height_ = height;
346
347 if (!initialized_) {
348 initialized_ = true;
349 const char vertext_shader_source[] =
350 "uniform mat4 u_mvpMatrix; \n"
351 "attribute vec4 a_position; \n"
352 "varying vec4 v_color; \n"
353 "void main() \n"
354 "{ \n"
355 " gl_Position = u_mvpMatrix * a_position; \n"
356 " v_color = vec4(a_position.x + 0.5, \n"
357 " a_position.y + 0.5, \n"
358 " a_position.z + 0.5, \n"
359 " 0.8); \n"
360 "} \n";
361
362 const char fragment_shader_source[] =
363 "precision mediump float; \n"
364 "varying vec4 v_color; \n"
365 "void main() \n"
366 "{ \n"
367 " gl_FragColor = v_color; \n"
368 "} \n";
369
370 state_->program_object_ = LoadProgram(
371 vertext_shader_source, fragment_shader_source);
372 state_->position_location_ = glGetAttribLocation(
373 state_->program_object_, "a_position");
374 state_->mvp_location_ = glGetUniformLocation(
375 state_->program_object_, "u_mvpMatrix");
376 state_->num_indices_ = GenerateCube(&state_->vbo_vertices_,
377 &state_->vbo_indices_);
378
379 glClearColor(0.0f, 0.0f, 0.0f, 0.2f);
380 }
381 }
382
OnGLContextLost()383 void SpinningCube::OnGLContextLost() {
384 // TODO(yzshen): Is it correct that in this case we don't need to do cleanup
385 // for program and buffers?
386 initialized_ = false;
387 height_ = 0;
388 width_ = 0;
389 state_->OnGLContextLost();
390 }
391
SetFlingMultiplier(float drag_distance,float drag_time)392 void SpinningCube::SetFlingMultiplier(float drag_distance,
393 float drag_time) {
394 fling_multiplier_ = RotationForDragDistance(drag_distance) /
395 RotationForTimeDelta(drag_time);
396
397 }
398
UpdateForTimeDelta(float delta_time)399 void SpinningCube::UpdateForTimeDelta(float delta_time) {
400 state_->angle_ += RotationForTimeDelta(delta_time) * fling_multiplier_;
401 if (state_->angle_ >= 360.0f)
402 state_->angle_ -= 360.0f;
403
404 // Arbitrary 50-step linear reduction in spin speed.
405 if (fling_multiplier_ > 1.0f) {
406 fling_multiplier_ =
407 std::max(1.0f, fling_multiplier_ - (fling_multiplier_ - 1.0f) / 50);
408 }
409
410 Update();
411 }
412
UpdateForDragDistance(float distance)413 void SpinningCube::UpdateForDragDistance(float distance) {
414 state_->angle_ += RotationForDragDistance(distance);
415 if (state_->angle_ >= 360.0f )
416 state_->angle_ -= 360.0f;
417
418 Update();
419 }
420
Draw()421 void SpinningCube::Draw() {
422 glViewport(0, 0, width_, height_);
423 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
424 glEnable(GL_DEPTH_TEST);
425 glUseProgram(state_->program_object_);
426
427 glBindBuffer(GL_ARRAY_BUFFER, state_->vbo_vertices_);
428 glVertexAttribPointer(state_->position_location_,
429 3,
430 GL_FLOAT,
431 GL_FALSE, 3 * sizeof(GLfloat),
432 0);
433 glEnableVertexAttribArray(state_->position_location_);
434
435 glUniformMatrix4fv(state_->mvp_location_,
436 1,
437 GL_FALSE,
438 (GLfloat*) &state_->mvp_matrix_.m[0][0]);
439 glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, state_->vbo_indices_);
440 glDrawElements(GL_TRIANGLES,
441 state_->num_indices_,
442 GL_UNSIGNED_SHORT,
443 0);
444 }
445
Update()446 void SpinningCube::Update() {
447 float aspect = static_cast<GLfloat>(width_) / static_cast<GLfloat>(height_);
448
449 ESMatrix perspective;
450 perspective.LoadIdentity();
451 perspective.Perspective(60.0f, aspect, 1.0f, 20.0f );
452
453 ESMatrix modelview;
454 modelview.LoadIdentity();
455 modelview.Translate(0.0, 0.0, -2.0);
456 modelview.Rotate(state_->angle_ * direction_, 1.0, 0.0, 1.0);
457
458 state_->mvp_matrix_.Multiply(&modelview, &perspective);
459 }
460