10dae86899a7faf8a885f419be31b1cda133c296
[pcsx_rearmed.git] / deps / libchdr / deps / zstd-1.5.5 / build / single_file_libs / examples / emscripten.c
1 /**
2  * \file emscripten.c
3  * Emscripten example of using the single-file \c zstddeclib. Draws a rotating
4  * textured quad with data from the in-line Zstd compressed DXT1 texture (DXT1
5  * being hardware compression, further compressed with Zstd).
6  * \n
7  * Compile using:
8  * \code
9  *      export CC_FLAGS="-Wall -Wextra -Werror -Os -g0 -flto --llvm-lto 3 -lGL -DNDEBUG=1"
10  *      export EM_FLAGS="-s WASM=1 -s ENVIRONMENT=web --shell-file shell.html --closure 1"
11  *      emcc $CC_FLAGS $EM_FLAGS -o out.html emscripten.c
12  * \endcode
13  * 
14  * \author Carl Woffenden, Numfum GmbH (released under a CC0 license)
15  */
16
17 #include <stddef.h>
18 #include <stdio.h>
19 #include <stdlib.h>
20 #include <string.h>
21
22 #include <emscripten/emscripten.h>
23 #include <emscripten/html5.h>
24
25 #include <GLES2/gl2.h>
26 #include <GLES2/gl2ext.h>
27
28 #include "../zstddeclib.c"
29
30 //************************* Test Data (DXT texture) **************************/
31
32 /**
33  * Zstd compressed DXT1 256x256 texture source.
34  * \n
35  * See \c testcard.png for the original.
36  */
37 static uint8_t const srcZstd[] = {
38 #include "testcard-zstd.inl"
39 };
40
41 /**
42  * Uncompressed size of \c #srcZstd.
43  */
44 #define DXT1_256x256 32768
45
46 /**
47  * Destination for decoding \c #srcZstd.
48  */
49 static uint8_t dstDxt1[DXT1_256x256] = {};
50
51 #ifndef ZSTD_VERSION_MAJOR
52 /**
53  * For the case where the decompression library hasn't been included we add a
54  * dummy function to fake the process and stop the buffers being optimised out.
55  */
56 size_t ZSTD_decompress(void* dst, size_t dstLen, const void* src, size_t srcLen) {
57         return (memcmp(dst, src, (srcLen < dstLen) ? srcLen : dstLen)) ? dstLen : 0;
58 }
59 #endif
60
61 //*************************** Program and Shaders ***************************/
62
63 /**
64  * Program object ID.
65  */
66 static GLuint progId = 0;
67
68 /**
69  * Vertex shader ID.
70  */
71 static GLuint vertId = 0;
72
73 /**
74  * Fragment shader ID.
75  */
76 static GLuint fragId = 0;
77
78 //********************************* Uniforms *********************************/
79
80 /**
81  * Quad rotation angle ID.
82  */
83 static GLint uRotId = -1;
84
85 /**
86  * Draw colour ID.
87  */
88 static GLint uTx0Id = -1;
89
90 //******************************* Shader Source ******************************/
91
92 /**
93  * Vertex shader to draw texture mapped polys with an applied rotation.
94  */
95 static GLchar const vertShader2D[] =
96 #if GL_ES_VERSION_2_0
97         "#version 100\n"
98         "precision mediump float;\n"
99 #else
100         "#version 120\n"
101 #endif
102         "uniform   float uRot;" // rotation
103         "attribute vec2  aPos;" // vertex position coords
104         "attribute vec2  aUV0;" // vertex texture UV0
105         "varying   vec2  vUV0;" // (passed to fragment shader)
106         "void main() {"
107         "       float cosA = cos(radians(uRot));"
108         "       float sinA = sin(radians(uRot));"
109         "       mat3 rot = mat3(cosA, -sinA, 0.0,"
110         "                                       sinA,  cosA, 0.0,"
111         "                                       0.0,   0.0,  1.0);"
112         "       gl_Position = vec4(rot * vec3(aPos, 1.0), 1.0);"
113         "       vUV0 = aUV0;"
114         "}";
115
116 /**
117  * Fragment shader for the above polys.
118  */
119 static GLchar const fragShader2D[] =
120 #if GL_ES_VERSION_2_0
121         "#version 100\n"
122         "precision mediump float;\n"
123 #else
124         "#version 120\n"
125 #endif
126         "uniform sampler2D uTx0;"
127         "varying vec2      vUV0;" // (passed from fragment shader)
128         "void main() {"
129         "       gl_FragColor = texture2D(uTx0, vUV0);"
130         "}";
131
132 /**
133  * Helper to compile a shader.
134  * 
135  * \param type shader type
136  * \param text shader source
137  * \return the shader ID (or zero if compilation failed)
138  */
139 static GLuint compileShader(GLenum const type, const GLchar* text) {
140         GLuint shader = glCreateShader(type);
141         if (shader) {
142                 glShaderSource (shader, 1, &text, NULL);
143                 glCompileShader(shader);
144                 GLint compiled;
145                 glGetShaderiv(shader, GL_COMPILE_STATUS, &compiled);
146                 if (compiled) {
147                         return shader;
148                 } else {
149                         GLint logLen;
150                         glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &logLen);
151                         if (logLen > 1) {
152                                 GLchar*  logStr = malloc(logLen);
153                                 glGetShaderInfoLog(shader, logLen, NULL, logStr);
154                         #ifndef NDEBUG
155                                 printf("Shader compilation error: %s\n", logStr);
156                         #endif
157                                 free(logStr);
158                         }
159                         glDeleteShader(shader);
160                 }
161         }
162         return 0;
163 }
164
165 //********************************** Helpers *********************************/
166
167 /**
168  * Vertex position index.
169  */
170 #define GL_VERT_POSXY_ID 0
171
172 /**
173  * Vertex UV0 index.
174  */
175 #define GL_VERT_TXUV0_ID 1
176
177  /**
178   * \c GL vec2 storage type.
179   */
180 struct vec2 {
181         float x;
182         float y;
183 };
184
185 /**
186  * Combined 2D vertex and 2D texture coordinates.
187  */
188 struct posTex2d {
189         struct vec2 pos;
190         struct vec2 uv0;
191 };
192
193 //****************************************************************************/
194
195 /**
196  * Current quad rotation angle (in degrees, updated per frame).
197  */
198 static float rotDeg = 0.0f;
199
200 /**
201  * Emscripten (single) GL context.
202  */
203 static EMSCRIPTEN_WEBGL_CONTEXT_HANDLE glCtx = 0;
204
205 /**
206  * Emscripten resize handler.
207  */
208 static EM_BOOL resize(int type, const EmscriptenUiEvent* e, void* data) {
209         double surfaceW;
210         double surfaceH;
211         if (emscripten_get_element_css_size   ("#canvas", &surfaceW, &surfaceH) == EMSCRIPTEN_RESULT_SUCCESS) {
212                 emscripten_set_canvas_element_size("#canvas",  surfaceW,  surfaceH);
213                 if (glCtx) {
214                         glViewport(0, 0, (int) surfaceW, (int) surfaceH);
215                 }
216         }
217         (void) type;
218         (void) data;
219         (void) e;
220         return EM_FALSE;
221 }
222
223 /**
224  * Boilerplate to create a WebGL context.
225  */
226 static EM_BOOL initContext() {
227         // Default attributes
228         EmscriptenWebGLContextAttributes attr;
229         emscripten_webgl_init_context_attributes(&attr);
230         if ((glCtx = emscripten_webgl_create_context("#canvas", &attr))) {
231                 // Bind the context and fire a resize to get the initial size
232                 emscripten_webgl_make_context_current(glCtx);
233                 emscripten_set_resize_callback(EMSCRIPTEN_EVENT_TARGET_DOCUMENT, NULL, EM_FALSE, resize);
234                 resize(0, NULL, NULL);
235                 return EM_TRUE;
236         }
237         return EM_FALSE;
238 }
239
240 /**
241  * Called once per frame (clears the screen and draws the rotating quad).
242  */
243 static void tick() {
244         glClearColor(1.0f, 0.0f, 1.0f, 1.0f);
245         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
246
247         if (uRotId >= 0) {
248                 glUniform1f(uRotId, rotDeg);
249                 rotDeg += 0.1f;
250                 if (rotDeg >= 360.0f) {
251                         rotDeg -= 360.0f;
252                 }
253         }
254
255         glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, 0);
256         glFlush();
257 }
258
259 /**
260  * Creates the GL context, shaders and quad data, decompresses the Zstd data
261  * and 'uploads' the resulting texture.
262  * 
263  * As a (naive) comparison, removing Zstd and building with "-Os -g0 s WASM=1
264  * -lGL emscripten.c" results in a 15kB WebAssembly file; re-adding Zstd
265  * increases the Wasm by 26kB.
266  */
267 int main() {
268         if (initContext()) {
269                 // Compile shaders and set the initial GL state
270                 if ((progId = glCreateProgram())) {
271                          vertId = compileShader(GL_VERTEX_SHADER,   vertShader2D);
272                          fragId = compileShader(GL_FRAGMENT_SHADER, fragShader2D);
273                          
274                          glBindAttribLocation(progId, GL_VERT_POSXY_ID, "aPos");
275                          glBindAttribLocation(progId, GL_VERT_TXUV0_ID, "aUV0");
276                          
277                          glAttachShader(progId, vertId);
278                          glAttachShader(progId, fragId);
279                          glLinkProgram (progId);
280                          glUseProgram  (progId);
281                          uRotId = glGetUniformLocation(progId, "uRot");
282                          uTx0Id = glGetUniformLocation(progId, "uTx0");
283                          if (uTx0Id >= 0) {
284                                  glUniform1i(uTx0Id, 0);
285                          }
286                         
287                          glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
288                          glEnable(GL_BLEND);
289                          glDisable(GL_DITHER);
290
291                          glCullFace(GL_BACK);
292                          glEnable(GL_CULL_FACE);
293                 }
294                 
295                 GLuint vertsBuf = 0;
296                 GLuint indexBuf = 0;
297                 GLuint txName   = 0;
298                 // Create the textured quad (vert positions then UVs)
299                 struct posTex2d verts2d[] = {
300                         {{-0.85f, -0.85f}, {0.0f, 0.0f}}, // BL
301                         {{ 0.85f, -0.85f}, {1.0f, 0.0f}}, // BR
302                         {{-0.85f,  0.85f}, {0.0f, 1.0f}}, // TL
303                         {{ 0.85f,  0.85f}, {1.0f, 1.0f}}, // TR
304                 };
305                 uint16_t index2d[] = {
306                         0, 1, 2,
307                         2, 1, 3,
308                 };
309                 glGenBuffers(1, &vertsBuf);
310                 glBindBuffer(GL_ARRAY_BUFFER, vertsBuf);
311                 glBufferData(GL_ARRAY_BUFFER,
312                         sizeof(verts2d), verts2d, GL_STATIC_DRAW);
313                 glVertexAttribPointer(GL_VERT_POSXY_ID, 2,
314                         GL_FLOAT, GL_FALSE, sizeof(struct posTex2d), 0);
315                 glVertexAttribPointer(GL_VERT_TXUV0_ID, 2,
316                         GL_FLOAT, GL_FALSE, sizeof(struct posTex2d),
317                                 (void*) offsetof(struct posTex2d, uv0));
318                 glGenBuffers(1, &indexBuf);
319                 glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuf);
320                 glBufferData(GL_ELEMENT_ARRAY_BUFFER,
321                         sizeof(index2d), index2d, GL_STATIC_DRAW);
322                 glEnableVertexAttribArray(GL_VERT_POSXY_ID);
323                 glEnableVertexAttribArray(GL_VERT_TXUV0_ID);
324                 
325                 // Decode the Zstd data and create the texture
326                 if (ZSTD_decompress(dstDxt1, DXT1_256x256, srcZstd, sizeof srcZstd) == DXT1_256x256) {
327                         glGenTextures(1, &txName);
328                         glBindTexture(GL_TEXTURE_2D, txName);
329                         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
330                         glCompressedTexImage2D(GL_TEXTURE_2D, 0,
331                                 GL_COMPRESSED_RGB_S3TC_DXT1_EXT,
332                                         256, 256, 0, DXT1_256x256, dstDxt1);
333                 } else {
334                         printf("Failed to decode Zstd data\n");
335                 }
336                 emscripten_set_main_loop(tick, 0, EM_FALSE);
337                 emscripten_exit_with_live_runtime();
338         }
339         return EXIT_FAILURE;
340 }