For example tried with the old GLFW (2.7) the following:
//========================================================================
// This is a small test application for GLFW.
// The program opens a window (640x480), and renders a spinning colored
// triangle (it is controlled with both the GLFW timer and the mouse). It
// also calculates the rendering speed (FPS), which is displayed in the
// window title bar.
//========================================================================
#include <stdio.h>
#include <stdlib.h>
#include <GL/glfw.h>
#include <emscripten/emscripten.h>
//========================================================================
// main()
//========================================================================
int main( void )
{
int width, height, running, x;
double t;
// Initialise GLFW
if( !glfwInit() )
{
fprintf( stderr, "Failed to initialize GLFW\n" );
exit( EXIT_FAILURE );
}
// Open OpenGL window
if( !glfwOpenWindow( 640, 480, 0,0,0,0, 0,0, GLFW_WINDOW ) )
{
fprintf( stderr, "Failed to open GLFW window\n" );
glfwTerminate();
exit( EXIT_FAILURE );
}
glfwSetWindowTitle( "Spinning Triangle" );
// Enable vertical sync (on cards that support it)
glfwSwapInterval( 1 );
// Main loop
running = GL_TRUE;
while( running )
{
// Get time and mouse position
t = glfwGetTime();
glfwGetMousePos( &x, NULL );
// Get window size (may be different than the requested size)
glfwGetWindowSize( &width, &height );
height = height > 0 ? height : 1;
// Set viewport
glViewport( 0, 0, width, height );
// Clear color buffer
glClearColor( 1.0f, 0.0f, 0.0f, 0.0f );
glClear( GL_COLOR_BUFFER_BIT );
// Swap buffers
glfwSwapBuffers();
// Check if the ESC key was pressed or the window was closed
running = !glfwGetKey( GLFW_KEY_ESC ) &&
glfwGetWindowParam( GLFW_OPENED );
}
// Close OpenGL window and terminate GLFW
glfwTerminate();
exit( EXIT_SUCCESS );
}
THe generated HTML shows only Emscripten GUI with "Running..." notification.
On Sat, Mar 8, 2014 at 6:05 PM, Michael IV <[email protected]> wrote:
> "Client side lack..." - good ! I just tried to use GLFW3 for context
> setup ,the emscripten compiled but nothing show up.Is it correct to assume
> it is not yet supported in the SDK?GLFW is useful as it can also create ES
> context.
>
>
> On Sat, Mar 8, 2014 at 5:53 PM, Jukka Jylänki <[email protected]> wrote:
>
>> Yeah, if you use GL 3 core on desktop, you'll be fairly good to go. The
>> shader syntax translation issue is a bit annoying, e.g. in core GL3 the
>> GLSL syntax uses the keywords in and out, whereas GLES2/WebGL still uses
>> the old keywords attribute and varying. There are a few other syntax
>> renames like this. What I do is I author my shaders in the old GLES2
>> syntax, and then when building for desktop, just use naive string replaces
>> at startup time to convert the shaders so they pass in core GL3. Also,
>> using VAOs is not required in GLES2 and WebGL, but it is mandatory in GL3.
>>
>> But these are GLES2 vs desktop GL differences, and not
>> Emscripten-specific differences. See the WebGL specification for WebGL vs
>> GLES2 differences. The most notable one is the lack of client side
>> rendering, which engines wouldn't want to use anyways.
>> On Mar 8, 2014 5:00 PM, "Michael IV" <[email protected]> wrote:
>>
>>> Ok,so let me see if I get you right.I can basically use GLEW with GL 3.0
>>> - GL 3.2 core profile and it will be translated ok (except of GLSL compat
>>> issues) to WebGL?Also,in terms of context creation,I see I can use GLFW or
>>> GLUT ?
>>>
>>>
>>> On Sat, Mar 8, 2014 at 4:56 PM, Jukka Jylänki <[email protected]> wrote:
>>>
>>>> In terms of features, pretty much WebGL is a subset of GLES2, which is
>>>> a subset of modern desktop GL. Sticking to the lowest common denomination
>>>> and basically writing "GLES2 without client-side rendering" gives you a
>>>> good sane common ground that works across all platforms. This means not
>>>> using any of the old desktop GL features such as fixed function rendering,
>>>> glBegin, glVertexPointer/glColorPointer etc. Also note that the extension
>>>> registryes are different for each GL, GLES and WebGL, although generally
>>>> matchable. If you also want to target desktop core GL3, that's also
>>>> possible, but one inconvenience there is that you need to maintain (or
>>>> translate one to other - that's what I do) two sets of GLSL shader syntax.
>>>> If you are working on a renderer codebase from scratch, it is best to avoid
>>>> the FULL_ES2 and LEGACY_GL_EMULATION settings, which gives the best path.
>>>>
>>>> Jukka
>>>> On Mar 8, 2014 4:42 PM, "Michael IV" <[email protected]> wrote:
>>>>
>>>>> I am desktop OpenGL developer and I wonder what's the best way for
>>>>> me to port or write OpenGL so that it will be best compatible with WebGL
>>>>> .I
>>>>> read in Emscripten FAQ that using SDK included ES2 API is the besr
>>>>> choice.But I also see some of the examples use regular OpenGL .For me ,in
>>>>> terms of portability and usability would be best to write a normal OpenGL
>>>>> ,using GLEW headers.Will it be fine as long as I use only ES2 compatible
>>>>> API methods?
>>>>>
>>>>> --
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>>>>> an email to [email protected].
>>>>>
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>>>>>
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>>>
>>>
>>>
>>> --
>>> Michael Ivanov
>>> Independent Pixel Commander
>>> onlygraphix.com
>>> Tel:+972 54 4962254
>>>
>>> --
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>> --
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>
>
>
> --
> Michael Ivanov
> Independent Pixel Commander
> onlygraphix.com
> Tel:+972 54 4962254
>
>
--
Michael Ivanov
Independent Pixel Commander
onlygraphix.com
Tel:+972 54 4962254
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