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/* |
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This is free and unencumbered software released into the public domain. |
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Anyone is free to copy, modify, publish, use, compile, sell, or |
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distribute this software, either in source code form or as a compiled |
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binary, for any purpose, commercial or non-commercial, and by any |
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means. |
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In jurisdictions that recognize copyright laws, the author or authors |
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of this software dedicate any and all copyright interest in the |
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software to the public domain. We make this dedication for the benefit |
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of the public at large and to the detriment of our heirs and |
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successors. We intend this dedication to be an overt act of |
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relinquishment in perpetuity of all present and future rights to this |
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software under copyright law. |
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
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EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
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MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. |
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IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR |
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OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, |
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ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR |
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OTHER DEALINGS IN THE SOFTWARE. |
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For more information, please refer to <http://unlicense.org/> |
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*/ |
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#include <emscripten/emscripten.h> |
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#include <emscripten/html5.h> |
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#define GL_GLEXT_PROTOTYPES |
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#define EGL_EGLEXT_PROTOTYPES |
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#include <GL/gl.h> |
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#include <GLES2/gl2.h> |
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#include <math.h> |
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static const char* vertex_shader_text = |
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"precision lowp float;" |
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"uniform mat4 uMVP;" |
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"attribute vec4 aPos;" |
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"attribute vec3 aCol;" |
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"varying vec3 vCol;" |
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"void main()" |
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"{" |
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"vCol = aCol;" |
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"gl_Position = uMVP * aPos;" |
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"}"; |
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static const char* fragment_shader_text = |
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"precision lowp float;" |
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"varying vec3 vCol;" |
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"void main()" |
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"{" |
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"gl_FragColor = vec4(vCol, 1.0);" |
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"}"; |
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typedef struct Vertex { float x, y, r, g, b; } Vertex; |
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static GLuint program, vertex_buffer; |
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static GLint uMVP_location, aPos_location, aCol_location; |
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int WAFNDraw(double f, void*); |
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// This function is called at startup |
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int main(int argc, char *argv[]) |
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{ |
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emscripten_set_canvas_element_size("canvas", 640, 480); |
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EmscriptenWebGLContextAttributes attrs; |
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emscripten_webgl_init_context_attributes(&attrs); |
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attrs.alpha = 0; |
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auto glContext = emscripten_webgl_create_context("canvas", &attrs); |
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emscripten_webgl_make_context_current(glContext); |
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glViewport(0, 0, 640, 480); |
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GLuint vertex_shader = glCreateShader(GL_VERTEX_SHADER); |
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glShaderSource(vertex_shader, 1, &vertex_shader_text, NULL); |
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glCompileShader(vertex_shader); |
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GLuint fragment_shader = glCreateShader(GL_FRAGMENT_SHADER); |
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glShaderSource(fragment_shader, 1, &fragment_shader_text, NULL); |
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glCompileShader(fragment_shader); |
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program = glCreateProgram(); |
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glAttachShader(program, vertex_shader); |
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glAttachShader(program, fragment_shader); |
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glLinkProgram(program); |
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uMVP_location = glGetUniformLocation(program, "uMVP"); |
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aPos_location = glGetAttribLocation(program, "aPos"); |
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aCol_location = glGetAttribLocation(program, "aCol"); |
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glGenBuffers(1, &vertex_buffer); |
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glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer); |
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glEnableVertexAttribArray(aPos_location); |
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glVertexAttribPointer(aPos_location, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)0); |
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glEnableVertexAttribArray(aCol_location); |
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glVertexAttribPointer(aCol_location, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)(sizeof(float) * 2)); |
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emscripten_request_animation_frame_loop(&WAFNDraw, 0); |
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return 0; |
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} |
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// This function is called by loader.js every frame |
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int WAFNDraw(double f, void*) |
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{ |
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f /= 1000.0; |
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glClear(GL_COLOR_BUFFER_BIT); |
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Vertex vertices[3] = |
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{ |
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{ -0.6f, -0.4f, 1.f, 0.f, 0.f }, |
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{ 0.6f, -0.4f, 0.f, 0.f, 1.f }, |
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{ 0.f, 0.6f, 1.f, 1.f, 1.f }, |
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}; |
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vertices[0].r = 0.5f + sinf(f * 3.14159f * 2.0f) * 0.5f; |
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vertices[1].b = 0.5f + cosf(f * 3.14159f * 2.0f) * 0.5f; |
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glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer); |
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glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW); |
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GLfloat mvp[4*4] = { 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, -1, 0, 0, 0, 0, 1 }; |
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glUseProgram(program); |
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glUniformMatrix4fv(uMVP_location, 1, GL_FALSE, mvp); |
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glDrawArrays(GL_TRIANGLES, 0, 3); |
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return EM_TRUE; |
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} |
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