Linux-VR-Compositor-Dev/examples/opengl/gl.c

/*
 * OpenHMD - Free and Open Source API and drivers for immersive technology.
 * Copyright (C) 2013 Fredrik Hultin.
 * Copyright (C) 2013 Jakob Bornecrantz.
 * Distributed under the Boost 1.0 licence, see LICENSE for full text.
 */

/* OpenGL Test - GL Helper Functions Implementation */

#include "gl.h"
#include <string.h>
#include <math.h>

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

#include <xcb/xcb.h>

#include "context.inl"

#ifdef __unix
#include <signal.h>
#endif

#ifndef M_PI
#define M_PI 3.14159265359
#endif

const uint32_t xcb_window_attrib_mask = XCB_CW_EVENT_MASK;
const uint32_t xcb_window_attrib_list[] = {
	XCB_EVENT_MASK_BUTTON_PRESS,
	XCB_EVENT_MASK_EXPOSURE,
	XCB_EVENT_MASK_KEY_PRESS,
};

void CreateWindow(const char *display_name,
		int window_x,
		int window_y,
		int window_width,
		int window_height,
		xcb_connection_t** out_connection,
		int* out_screen,
		xcb_window_t* out_window) {

	xcb_generic_error_t* error;

	//int iscreen;

	xcb_connection_t *connection = xcb_connect(NULL, NULL);
	if (!connection)
		exit(-1);
	if (xcb_connection_has_error(connection))
		exit(-1);

	const xcb_setup_t* setup = xcb_get_setup(connection);
	xcb_screen_t* screen = xcb_setup_roots_iterator(setup).data;
	assert(screen != 0);

	xcb_window_t window = xcb_generate_id(connection);
	if (window <= 0)
		exit(-1);

	xcb_void_cookie_t create_cookie = xcb_create_window_checked(
		connection,
		XCB_COPY_FROM_PARENT, // depth
		window,
		screen->root, // parent window
		window_x,
		window_y,
		window_width,
		window_height,
		0, // border width
		XCB_WINDOW_CLASS_INPUT_OUTPUT, // class
		screen->root_visual, // visual
		xcb_window_attrib_mask,
		xcb_window_attrib_list);

	xcb_void_cookie_t map_cookie = xcb_map_window_checked(connection, window);

	// Check errors.
	error = xcb_request_check(connection, create_cookie);
	if (error)
		exit(-1);
	error = xcb_request_check(connection, map_cookie);
	if (error)
		exit(-1);

	*out_connection = connection;
	*out_window = window;
}

static const EGLint egl_config_attribs[] = {
	//EGL_COLOR_BUFFER_TYPE,     EGL_RGB_BUFFER,
	//EGL_BUFFER_SIZE,           32,
	EGL_RED_SIZE,              8,
	EGL_GREEN_SIZE,            8,
	EGL_BLUE_SIZE,             8,
	EGL_ALPHA_SIZE,            8,

	//EGL_DEPTH_SIZE,            24,
	//EGL_STENCIL_SIZE,          8,

	//EGL_SAMPLE_BUFFERS,        0,
	//EGL_SAMPLES,               0,

	EGL_SURFACE_TYPE,          EGL_WINDOW_BIT,
	EGL_RENDERABLE_TYPE,       EGL_OPENGL_BIT,

	EGL_NONE,
};

static const EGLint egl_context_attribs[] = {
	EGL_CONTEXT_CLIENT_VERSION, 2,
	EGL_NONE
};

static const EGLint egl_surface_attribs[] = {
	EGL_RENDER_BUFFER, EGL_BACK_BUFFER,
	EGL_NONE,
};

void init_gl(gl_ctx* ctx, int w, int h)
{
	memset(ctx, 0, sizeof(gl_ctx));

	const char *x_display_name = NULL;

	CreateWindow(x_display_name,
			0, 0, // x, y
			w, h, // width, height
			&ctx->x_connection,
			&ctx->x_screen,
			&ctx->x_window);

	if(ctx->x_window == NULL)
	{
		printf("CreateWindow failed\n");
		exit(-1);
	}

	ctx->w = w;
	ctx->h = h;
	ctx->is_fullscreen = 0;

	bool bContextCreated = create_context(EGL_DEFAULT_DISPLAY, ctx->x_window, egl_config_attribs, egl_context_attribs, egl_surface_attribs, &ctx->egl_display, &ctx->egl_context, &ctx->egl_surface);

	if(!bContextCreated || ctx->egl_context == EGL_NO_CONTEXT)
	{
		printf("CreateContext failed\n");
		exit(-1);
	}

	// Disable ctrl-c catching on Linux (and OS X?)
#ifdef __unix
	signal(SIGINT, SIG_DFL);
#endif

	printf("OpenGL Renderer: %s\n", glGetString(GL_RENDERER));
	printf("OpenGL Vendor: %s\n", glGetString(GL_VENDOR));
	printf("OpenGL Version: %s\n", glGetString(GL_VERSION));

	// == Initialize OpenGL ==
	glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
	glClear(GL_COLOR_BUFFER_BIT);

	glEnable(GL_BLEND);
	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
	glEnable(GL_ALPHA_TEST);
	glLoadIdentity();

	glShadeModel(GL_SMOOTH);
	glDisable(GL_DEPTH_TEST);
	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
	glLoadIdentity();

	glMatrixMode(GL_PROJECTION);
	glEnable(GL_POLYGON_SMOOTH);
	glLoadIdentity();

	glViewport(0, 0, ctx->w, ctx->h);
}

void ortho(gl_ctx* ctx)
{
	glMatrixMode(GL_PROJECTION);
	//glPushMatrix();
	glLoadIdentity();

	glOrtho(0.0f, ctx->w, ctx->h, 0.0f, -1.0f, 1.0f);
	glMatrixMode(GL_MODELVIEW);
	//glPushMatrix();
	glLoadIdentity();

	glDisable(GL_DEPTH_TEST);
	glDisable(GL_DEPTH);

	glDisable(GL_MULTISAMPLE);
}

void draw_cube()
{
	glBegin(GL_QUADS);

	glVertex3f(  0.5f,  0.5f, -0.5f); /* Top Right Of The Quad (Top)      */
	glVertex3f( -0.5f,  0.5f, -0.5f); /* Top Left Of The Quad (Top)       */
	glVertex3f( -0.5f,  0.5f,  0.5f); /* Bottom Left Of The Quad (Top)    */
	glVertex3f(  0.5f,  0.5f,  0.5f); /* Bottom Right Of The Quad (Top)   */

	glVertex3f(  0.5f, -0.5f,  0.5f); /* Top Right Of The Quad (Botm)     */
	glVertex3f( -0.5f, -0.5f,  0.5f); /* Top Left Of The Quad (Botm)      */
	glVertex3f( -0.5f, -0.5f, -0.5f); /* Bottom Left Of The Quad (Botm)   */
	glVertex3f(  0.5f, -0.5f, -0.5f); /* Bottom Right Of The Quad (Botm)  */

	glVertex3f(  0.5f,  0.5f,  0.5f); /* Top Right Of The Quad (Front)    */
	glVertex3f( -0.5f,  0.5f,  0.5f); /* Top Left Of The Quad (Front)     */
	glVertex3f( -0.5f, -0.5f,  0.5f); /* Bottom Left Of The Quad (Front)  */
	glVertex3f(  0.5f, -0.5f,  0.5f); /* Bottom Right Of The Quad (Front) */

	glVertex3f(  0.5f, -0.5f, -0.5f); /* Bottom Left Of The Quad (Back)   */
	glVertex3f( -0.5f, -0.5f, -0.5f); /* Bottom Right Of The Quad (Back)  */
	glVertex3f( -0.5f,  0.5f, -0.5f); /* Top Right Of The Quad (Back)     */
	glVertex3f(  0.5f,  0.5f, -0.5f); /* Top Left Of The Quad (Back)      */

	glVertex3f( -0.5f,  0.5f,  0.5f); /* Top Right Of The Quad (Left)     */
	glVertex3f( -0.5f,  0.5f, -0.5f); /* Top Left Of The Quad (Left)      */
	glVertex3f( -0.5f, -0.5f, -0.5f); /* Bottom Left Of The Quad (Left)   */
	glVertex3f( -0.5f, -0.5f,  0.5f); /* Bottom Right Of The Quad (Left)  */

	glVertex3f(  0.5f,  0.5f, -0.5f); /* Top Right Of The Quad (Right)    */
	glVertex3f(  0.5f,  0.5f,  0.5f); /* Top Left Of The Quad (Right)     */
	glVertex3f(  0.5f, -0.5f,  0.5f); /* Bottom Left Of The Quad (Right)  */
	glVertex3f(  0.5f, -0.5f, -0.5f); /* Bottom Right Of The Quad (Right) */

	glEnd();

}

static void compile_shader_src(GLuint shader, const char* src)
{
	glShaderSource(shader, 1, &src, NULL);
	glCompileShader(shader);

	GLint status;
	GLint length;
	char log[4096] = {0};

	glGetShaderiv(shader, GL_COMPILE_STATUS, &status);
	glGetShaderInfoLog(shader, 4096, &length, log);
	if(status == GL_FALSE){
		printf("compile failed %s\n", log);
	}
}

GLuint compile_shader(const char* vertex, const char* fragment)
{
	// Create the handels
	GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
	GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
	GLuint programShader = glCreateProgram();

	// Attach the shaders to a program handel.
	glAttachShader(programShader, vertexShader);
	glAttachShader(programShader, fragmentShader);

	// Load and compile the Vertex Shader
	compile_shader_src(vertexShader, vertex);

	// Load and compile the Fragment Shader
	compile_shader_src(fragmentShader, fragment);

	// The shader objects are not needed any more,
	// the programShader is the complete shader to be used.
	glDeleteShader(vertexShader);
	glDeleteShader(fragmentShader);

	glLinkProgram(programShader);

	GLint status;
	GLint length;
	char log[4096] = {0};

	glGetProgramiv(programShader, GL_LINK_STATUS, &status);
	glGetProgramInfoLog(programShader, 4096, &length, log);
	if(status == GL_FALSE){
		printf("link failed %s\n", log);
	}

	return programShader;
}

void create_fbo(int eye_width, int eye_height, GLuint* fbo, GLuint* color_tex, GLuint* depth_tex)
{
	glGenTextures(1, color_tex);
	glGenTextures(1, depth_tex);
	glGenFramebuffers(1, fbo);

	glBindTexture(GL_TEXTURE_2D, *color_tex);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, eye_width, eye_height, 0, GL_RGBA, GL_UNSIGNED_INT, NULL);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

	glBindTexture(GL_TEXTURE_2D, *depth_tex);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT24, eye_width, eye_height, 0, GL_DEPTH_COMPONENT, GL_UNSIGNED_BYTE, NULL);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
	glBindTexture(GL_TEXTURE_2D, 0);

	glBindFramebuffer(GL_FRAMEBUFFER_EXT, *fbo);
	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, *color_tex, 0);
	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, *depth_tex, 0);

	GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER_EXT);

	if(status != GL_FRAMEBUFFER_COMPLETE_EXT){
		printf("failed to create fbo %x\n", status);
	}
	glBindFramebuffer(GL_FRAMEBUFFER_EXT, 0);
}