hello_wayland_EGL/SOURCES/graphics/os/EGL/egl_context.c

#include "egl_context.h"

#include <stdlib.h>
#include <stdio.h>

void printEGLError(){
	EGLint errorCode = eglGetError();
	switch (errorCode){
		case EGL_SUCCESS:
			printf("EGL_SUCCESS : The last function succeeded without error.\n");
		break;
		case EGL_NOT_INITIALIZED:
			printf("EGL_NOT_INITIALIZED : EGL is not initialized, or could not be initialized, for the specified EGL display connection.\n");
		break;
		case EGL_BAD_ACCESS:
			printf("EGL_BAD_ACCESS : EGL cannot access a requested resource (for example a context is bound in another thread).\n");
		break;
		case EGL_BAD_ALLOC:
			printf("EGL_BAD_ALLOC : EGL failed to allocate resources for the requested operation.\n");
		break;
		case EGL_BAD_ATTRIBUTE:
			printf("EGL_BAD_ATTRIBUTE : An unrecognized attribute or attribute value was passed in the attribute list.\n");
		break;
		case EGL_BAD_CONTEXT:
			printf("EGL_BAD_CONTEXT : An EGLContext argument does not name a valid EGL rendering context.\n");
		break;
		case EGL_BAD_CONFIG:
			printf("EGL_BAD_CONFIG : An EGLConfig argument does not name a valid EGL frame buffer configuration.\n");
		break;
		case EGL_BAD_CURRENT_SURFACE:
			printf("EGL_BAD_CURRENT_SURFACE : The current surface of the calling thread is a window, pixel buffer or pixmap that is no longer valid.\n");
		break;
		case EGL_BAD_DISPLAY:
			printf("EGL_BAD_DISPLAY : An EGLDisplay argument does not name a valid EGL display connection.\n");
		break;
		case EGL_BAD_SURFACE:
			printf("EGL_BAD_SURFACE : An EGLSurface argument does not name a valid surface (window, pixel buffer or pixmap) configured for GL rendering.\n");
		break;
		case EGL_BAD_MATCH:
			printf("EGL_BAD_MATCH : Arguments are inconsistent (for example, a valid context requires buffers not supplied by a valid surface).\n");
		break;
		case EGL_BAD_PARAMETER:
			printf("EGL_BAD_PARAMETER : One or more argument values are invalid.\n");
		break;
		case EGL_BAD_NATIVE_PIXMAP:
			printf("EGL_BAD_NATIVE_PIXMAP : A NativePixmapType argument does not refer to a valid native pixmap.\n");
		break;
		case EGL_BAD_NATIVE_WINDOW:
			printf("EGL_BAD_NATIVE_WINDOW : A NativeWindowType argument does not refer to a valid native window.\n");
		break;
		case EGL_CONTEXT_LOST:
			printf("EGL_CONTEXT_LOST : A power management event has occurred. The application must destroy all contexts and reinitialise OpenGL ES state and objects to continue rendering.\n");
		break; 
		default:
			printf("UNKNOWN : wtf dude\n");
	}
}

egl_context *egl_context_malloc() {
	return malloc( sizeof( egl_context));
}

/*
	wl_display, wl_surface, w, h
	egl_window CREATE
	egl_display CREATE
	egl_config FIND

	egl_surface CREATE
	
	egl_context CREATE
*/
egl_context *egl_context_new( struct wl_display *display) {
	EGLint major;
	EGLint minor;
	EGLint num_configs;

	EGLint lastEGLOp;
	/*
	replaced EGL_OPENGL_BIT with EGL_OPENGL_ES2_BIT 
	*/
	EGLint attribs[] = {
		EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,
		EGL_NONE
	};

	egl_context *e = egl_context_malloc();

	e->display = eglGetDisplay((EGLNativeDisplayType) display);

	if(EGL_NO_DISPLAY == e->display) {
		fprintf(stderr, "Couldn't get EGL display\n");
		exit(EXIT_FAILURE);
	}

	if( EGL_TRUE != eglInitialize(e->display, &major, &minor)) {
		fprintf(stderr, "Couldnt initialize EGL\n");
		exit(EXIT_FAILURE);
	}


	/* null buffer for querying the count*/
	lastEGLOp = eglChooseConfig( e->display, attribs, NULL, 1, &num_configs);
	if( EGL_TRUE != lastEGLOp) {
		exit(EXIT_FAILURE);
	}
	fprintf(stderr, "found %d matching EGL configurations\n", num_configs);
	
	EGLConfig *all_the_configs = malloc( num_configs * sizeof( EGLConfig));

	/* was &e->config but broken */
	lastEGLOp = eglChooseConfig( e->display, attribs, all_the_configs, num_configs, &num_configs);
	if( EGL_TRUE != lastEGLOp) {
		fprintf(stderr, "CouldnÄt find matching EGL config\n");
		exit(EXIT_FAILURE);
	}

	e->config = all_the_configs[0];

	/* added from 
		https://stackoverflow.com/questions/25843368/glgetstringgl-version-returns-opengl-es-cm-1-1-but-my-phone-supports-opengl
	*/
	const EGLint context_attrib_list[] = { 
        	// request a context using Open GL ES 2.0
        	EGL_CONTEXT_CLIENT_VERSION, 2, 
        	EGL_NONE 
	};

	/*thanks to the dudes of stackoverflow for explaining how the attrib_list works*/
	e->context = eglCreateContext(e->display, e->config, EGL_NO_CONTEXT, context_attrib_list);
	if( EGL_NO_CONTEXT == e->context) {
		fprintf(stderr, "Couldn't create EGL context\n");
		printEGLError();
		exit(EXIT_FAILURE);
	}

	return e;
}