add some simple EGL output code

my first ever GL code, yay!

gl.c

@@ -0,0 +1,178 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <EGL/egl.h>
+#include <GLES/gl.h>
+#include "gl.h"
+
+static EGLDisplay edpy;
+static EGLSurface esfc;
+static EGLContext ectxt;
+
+static int gl_have_error(const char *name)
+{
+	GLenum e = glGetError();
+	if (e != GL_NO_ERROR) {
+		fprintf(stderr, "GL error: %s %x\n", name, e);
+		return 1;
+	}
+	return 0;
+}
+
+static int gles_have_error(const char *name)
+{
+	EGLint e = eglGetError();
+	if (e != EGL_SUCCESS) {
+		fprintf(stderr, "%s %x\n", name, e);
+		return 1;
+	}
+	return 0;
+}
+
+int gl_init(void *display, void *window)
+{
+	EGLConfig ecfg = NULL;
+	GLuint texture_name = 0;
+	void *tmp_texture_mem = NULL;
+	EGLint num_config;
+	int retval = -1;
+	int ret;
+	EGLint attr[] =
+	{
+		EGL_NONE
+	};
+
+	tmp_texture_mem = calloc(1, 1024 * 512 * 2);
+	if (tmp_texture_mem == NULL) {
+		fprintf(stderr, "OOM\n");
+		goto out;
+	}
+
+	edpy = eglGetDisplay((EGLNativeDisplayType)display);
+	if (edpy == EGL_NO_DISPLAY) {
+		fprintf(stderr, "Failed to get EGL display\n");
+		goto out;
+	}
+
+	if (!eglInitialize(edpy, NULL, NULL)) {
+		fprintf(stderr, "Failed to initialize EGL\n");
+		goto out;
+	}
+
+	if (!eglChooseConfig(edpy, attr, &ecfg, 1, &num_config)) {
+		fprintf(stderr, "Failed to choose config (%x)\n", eglGetError());
+		goto out;
+	}
+
+	if (ecfg == NULL || num_config == 0) {
+		fprintf(stderr, "No EGL configs available\n");
+		goto out;
+	}
+
+	esfc = eglCreateWindowSurface(edpy, ecfg,
+		(EGLNativeWindowType)window, NULL);
+	if (esfc == EGL_NO_SURFACE) {
+		fprintf(stderr, "Unable to create EGL surface (%x)\n",
+			eglGetError());
+		goto out;
+	}
+
+	ectxt = eglCreateContext(edpy, ecfg, EGL_NO_CONTEXT, NULL);
+	if (ectxt == EGL_NO_CONTEXT) {
+		fprintf(stderr, "Unable to create EGL context (%x)\n",
+			eglGetError());
+		goto out;
+	}
+
+	eglMakeCurrent(edpy, esfc, esfc, ectxt);
+
+	glEnable(GL_TEXTURE_2D);
+
+	glGenTextures(1, &texture_name);
+
+	glBindTexture(GL_TEXTURE_2D, texture_name);
+
+	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 1024, 512, 0, GL_RGB,
+		GL_UNSIGNED_SHORT_5_6_5, tmp_texture_mem);
+	if (gl_have_error("glTexImage2D"))
+		goto out;
+
+	// no mipmaps
+	glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+	glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+
+	//glViewport(0, 0, 512, 512);
+	glLoadIdentity();
+	glFrontFace(GL_CW);
+	glEnable(GL_CULL_FACE);
+
+	glEnableClientState(GL_TEXTURE_COORD_ARRAY);
+	glEnableClientState(GL_VERTEX_ARRAY);
+
+	if (gl_have_error("init"))
+		goto out;
+
+	retval = 0;
+out:
+	free(tmp_texture_mem);
+	return retval;
+}
+
+static float vertices[] = {
+	-1.0f,  1.0f,  0.0f, // 0    0  1
+	 1.0f,  1.0f,  0.0f, // 1  ^
+	-1.0f, -1.0f,  0.0f, // 2  | 2  3
+	 1.0f, -1.0f,  0.0f, // 3  +-->
+};
+
+static float texture[] = {
+	0.0f, 0.0f, // we flip this:
+	1.0f, 0.0f, // v^
+	0.0f, 1.0f, //  |  u
+	1.0f, 1.0f, //  +-->
+};
+
+int gl_flip(const void *fb, int w, int h)
+{
+	static int old_w, old_h;
+
+	if (w != old_w || h != old_h) {
+		float f_w = (float)w / 1024.0f;
+		float f_h = (float)h / 512.0f;
+		texture[1*2 + 0] = f_w;
+		texture[2*2 + 1] = f_h;
+		texture[3*2 + 0] = f_w;
+		texture[3*2 + 1] = f_h;
+		old_w = w;
+		old_h = h;
+	}
+
+	glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, w, h,
+		GL_RGB, GL_UNSIGNED_SHORT_5_6_5, fb);
+	if (gl_have_error("glTexSubImage2D"))
+		return -1;
+
+	glVertexPointer(3, GL_FLOAT, 0, vertices);
+	glTexCoordPointer(2, GL_FLOAT, 0, texture);
+	glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+
+	if (gl_have_error("glDrawArrays"))
+		return -1;
+
+	eglSwapBuffers(edpy, esfc);
+	if (gles_have_error("eglSwapBuffers"))
+		return -1;
+
+	return 0;
+}
+
+void gl_finish(void)
+{
+	eglMakeCurrent(edpy, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
+	eglDestroyContext(edpy, ectxt);
+	ectxt = EGL_NO_CONTEXT;
+	eglDestroySurface(edpy, esfc);
+	esfc = EGL_NO_SURFACE;
+	eglTerminate(edpy);
+	edpy = EGL_NO_DISPLAY;
+}

gl.h

@@ -0,0 +1,13 @@
+#ifdef HAVE_GLES
+
+int gl_init(void *display, void *window);
+int gl_flip(const void *fb, int w, int h);
+void gl_finish(void);
+
+#else
+
+static __inline int gl_init(void *display, void *window) { return -1; }
+static __inline int gl_flip(const void *fb, int w, int h) { return -1; }
+static __inline void gl_finish(void) {}
+
+#endif