node_editor.c

/* nuklear - v1.00 - public domain */
/* This is a simple node editor just to show a simple implementation and that
 * it is possible to achieve it with this library. While all nodes inside this
 * example use a simple color modifier as content you could change them
 * to have your custom content depending on the node time.
 * Biggest difference to most usual implementation is that this example does
 * not have connectors on the right position of the property that it links.
 * This is mainly done out of laziness and could be implemented as well but
 * requires calculating the position of all rows and add connectors.
 * In addition adding and removing nodes is quite limited at the
 * moment since it is based on a simple fixed array. If this is to be converted
 * into something more serious it is probably best to extend it.*/
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdarg.h>
#include <string.h>
#include <math.h>
#include <assert.h>
#include <math.h>
#include <time.h>
#include <limits.h>

#include <GL/glew.h>
#include <GL/gl.h>
#include <GL/glu.h>
#include <GLFW/glfw3.h>

#define NK_INCLUDE_FIXED_TYPES
#define NK_INCLUDE_STANDARD_IO
#define NK_INCLUDE_DEFAULT_ALLOCATOR
#define NK_INCLUDE_VERTEX_BUFFER_OUTPUT
#define NK_INCLUDE_FONT_BAKING
#define NK_INCLUDE_DEFAULT_FONT
#define NK_IMPLEMENTATION
#include "../nuklear.h"

/* macros */
#define WINDOW_WIDTH 800
#define WINDOW_HEIGHT 600

#define MAX_VERTEX_MEMORY 512 * 1024
#define MAX_ELEMENT_MEMORY 128 * 1024

#define UNUSED(a) (void)a
#define MIN(a,b) ((a) < (b) ? (a) : (b))
#define MAX(a,b) ((a) < (b) ? (b) : (a))
#define LEN(a) (sizeof(a)/sizeof(a)[0])

/* ===============================================================
 *
 *                          NODE EDITOR
 *
 * ===============================================================*/
struct node {
    int ID;
    char name[32];
    struct nk_rect bounds;
    float value;
    struct nk_color color;
    int input_count;
    int output_count;
    struct node *next;
    struct node *prev;
};

struct node_link {
    int input_id;
    int input_slot;
    int output_id;
    int output_slot;
    struct nk_vec2 in;
    struct nk_vec2 out;
};

struct node_linking {
    int active;
    struct node *node;
    int input_id;
    int input_slot;
};

struct node_editor {
    struct node node_buf[32];
    struct node_link links[64];
    struct node *begin;
    struct node *end;
    int node_count;
    int link_count;
    struct nk_rect bounds;
    struct node *selected;
    int show_grid;
    struct nk_vec2 scrolling;
    struct node_linking linking;
};

static void
node_editor_push(struct node_editor *editor, struct node *node)
{
    if (!editor->begin) {
        node->next = NULL;
        node->prev = NULL;
        editor->begin = node;
        editor->end = node;
    } else {
        node->prev = editor->end;
        if (editor->end)
            editor->end->next = node;
        node->next = NULL;
        editor->end = node;
    }
}

static void
node_editor_pop(struct node_editor *editor, struct node *node)
{
    if (node->next)
        node->next->prev = node->prev;
    if (node->prev)
        node->prev->next = node->next;
    if (editor->end == node)
        editor->end = node->prev;
    if (editor->begin == node)
        editor->begin = node->next;
    node->next = NULL;
    node->prev = NULL;
}

static struct node*
node_editor_find(struct node_editor *editor, int ID)
{
    struct node *iter = editor->begin;
    while (iter) {
        if (iter->ID == ID)
            return iter;
        iter = iter->next;
    }
    return NULL;
}

static void
node_editor_add(struct node_editor *editor, const char *name, struct nk_rect bounds,
    struct nk_color col, int in_count, int out_count)
{
    static int IDs = 0;
    struct node *node;
    assert((nk_size)editor->node_count < LEN(editor->node_buf));
    node = &editor->node_buf[editor->node_count++];
    node->ID = IDs++;
    node->value = 0;
    node->color = nk_rgb(255, 0, 0);
    node->input_count = in_count;
    node->output_count = out_count;
    node->color = col;
    node->bounds = bounds;
    strcpy(node->name, name);
    node_editor_push(editor, node);
}

static void
node_editor_link(struct node_editor *editor, int in_id, int in_slot,
    int out_id, int out_slot)
{
    struct node_link *link;
    assert((nk_size)editor->link_count < LEN(editor->links));
    link = &editor->links[editor->link_count++];
    link->input_id = in_id;
    link->input_slot = in_slot;
    link->output_id = out_id;
    link->output_slot = out_slot;
}

static void
node_editor_init(struct node_editor *editor)
{
    memset(editor, 0, sizeof(*editor));
    editor->begin = NULL;
    editor->end = NULL;
    node_editor_add(editor, "Source", nk_rect(-40, 10, 180, 220), nk_rgb(255, 0, 0), 0, 1);
    node_editor_add(editor, "Source", nk_rect(-40, 260, 180, 220), nk_rgb(0, 255, 0), 0, 1);
    node_editor_add(editor, "Combine", nk_rect(400, 100, 180, 220), nk_rgb(0,0,255), 2, 2);
    node_editor_link(editor, 0, 0, 2, 0);
    node_editor_link(editor, 1, 0, 2, 1);
    editor->show_grid = nk_true;
}

static int
node_editor_run(struct node_editor *nodedit, struct nk_context *ctx)
{
    int n = 0;
    struct nk_rect total_space;
    const struct nk_input *in = &ctx->input;
    struct nk_command_buffer *canvas;
    struct node *updated = 0;
    struct nk_panel layout;

    if (nk_begin(ctx, &layout, "Node Editor", nk_rect(50, 50, WINDOW_WIDTH, WINDOW_HEIGHT),
        NK_WINDOW_BORDER|NK_WINDOW_NO_SCROLLBAR|NK_WINDOW_MOVABLE))
    {
        /* allocate complete window space */
        canvas = nk_window_get_canvas(ctx);
        total_space = nk_window_get_content_region(ctx);
        nk_layout_space_begin(ctx, NK_STATIC, total_space.h, nodedit->node_count);
        {
            struct nk_panel node, menu;
            struct node *it = nodedit->begin;
            struct nk_rect size = nk_layout_space_bounds(ctx);

            if (nodedit->show_grid) {
                /* display grid */
                float x, y;
                const float grid_size = 32.0f;
                const struct nk_color grid_color = nk_rgb(50, 50, 50);
                for (x = (float)fmod(size.x - nodedit->scrolling.x, grid_size); x < size.w; x += grid_size)
                    nk_stroke_line(canvas, x+size.x, size.y, x+size.x, size.y+size.h, 1.0f, grid_color);
                for (y = (float)fmod(size.y - nodedit->scrolling.y, grid_size); y < size.h; y += grid_size)
                    nk_stroke_line(canvas, size.x, y+size.y, size.x+size.w, y+size.y, 1.0f, grid_color);
            }

            /* execute each node as a movable group */
            while (it) {
                /* calculate scrolled node window position and size */
                nk_layout_space_push(ctx, nk_rect(it->bounds.x - nodedit->scrolling.x,
                    it->bounds.y - nodedit->scrolling.y, it->bounds.w, it->bounds.h));

                /* execute node window */
                if (nk_group_begin(ctx, &node, it->name, NK_WINDOW_MOVABLE|NK_WINDOW_NO_SCROLLBAR|NK_WINDOW_BORDER|NK_WINDOW_TITLE))
                {
                    /* always have last selected node on top */
                    if (nk_input_mouse_clicked(in, NK_BUTTON_LEFT, node.bounds) &&
                        (!(it->prev && nk_input_mouse_clicked(in, NK_BUTTON_LEFT,
                        nk_layout_space_rect_to_screen(ctx, node.bounds)))) &&
                        nodedit->end != it)
                    {
                        updated = it;
                    }

                    /* ================= NODE CONTENT =====================*/
                    nk_layout_row_dynamic(ctx, 25, 1);
                    nk_button_color(ctx, it->color, NK_BUTTON_DEFAULT);
                    it->color.r = (nk_byte)nk_propertyi(ctx, "#R:", 0, it->color.r, 255, 1,1);
                    it->color.g = (nk_byte)nk_propertyi(ctx, "#G:", 0, it->color.g, 255, 1,1);
                    it->color.b = (nk_byte)nk_propertyi(ctx, "#B:", 0, it->color.b, 255, 1,1);
                    it->color.a = (nk_byte)nk_propertyi(ctx, "#A:", 0, it->color.a, 255, 1,1);
                    /* ====================================================*/
                    nk_group_end(ctx);
                }
                {
                    /* node connector and linking */
                    float space;
                    struct nk_rect bounds;
                    bounds = nk_layout_space_rect_to_local(ctx, node.bounds);
                    bounds.x += nodedit->scrolling.x - ctx->style.window.border;
                    bounds.y += nodedit->scrolling.y - ctx->style.window.border;
                    bounds.w += 2*ctx->style.window.border;
                    bounds.h += 2*ctx->style.window.border;

                    it->bounds = bounds;

                    /* output connector */
                    space = node.bounds.h / (float)((it->output_count) + 1);
                    for (n = 0; n < it->output_count; ++n) {
                        struct nk_rect circle;
                        circle.x = node.bounds.x + node.bounds.w-4;
                        circle.y = node.bounds.y + space * (float)(n+1);
                        circle.w = 8; circle.h = 8;
                        nk_fill_circle(canvas, circle, nk_rgb(100, 100, 100));

                        /* start linking process */
                        if (nk_input_has_mouse_click_down_in_rect(in, NK_BUTTON_LEFT, circle, nk_true)) {
                            nodedit->linking.active = nk_true;
                            nodedit->linking.node = it;
                            nodedit->linking.input_id = it->ID;
                            nodedit->linking.input_slot = n;
                        }

                        /* draw curve from linked node slot to mouse position */
                        if (nodedit->linking.active && nodedit->linking.node == it &&
                            nodedit->linking.input_slot == n) {
                            struct nk_vec2 l0 = nk_vec2(circle.x + 3, circle.y + 3);
                            struct nk_vec2 l1 = in->mouse.pos;
                            nk_stroke_curve(canvas, l0.x, l0.y, l0.x + 50.0f, l0.y,
                                l1.x - 50.0f, l1.y, l1.x, l1.y, 1.0f, nk_rgb(100, 100, 100));
                        }
                    }

                    /* input connector */
                    space = node.bounds.h / (float)((it->input_count) + 1);
                    for (n = 0; n < it->input_count; ++n) {
                        struct nk_rect circle;
                        circle.x = node.bounds.x-4;
                        circle.y = node.bounds.y + space * (float)(n+1);
                        circle.w = 8; circle.h = 8;
                        nk_fill_circle(canvas, circle, nk_rgb(100, 100, 100));
                        if (nk_input_is_mouse_released(in, NK_BUTTON_LEFT) &&
                            nk_input_is_mouse_hovering_rect(in, circle) &&
                            nodedit->linking.active && nodedit->linking.node != it) {
                            nodedit->linking.active = nk_false;
                            node_editor_link(nodedit, nodedit->linking.input_id,
                                nodedit->linking.input_slot, it->ID, n);
                        }
                    }
                }
                it = it->next;
            }

            /* reset linking connection */
            if (nodedit->linking.active && nk_input_is_mouse_released(in, NK_BUTTON_LEFT)) {
                nodedit->linking.active = nk_false;
                nodedit->linking.node = NULL;
                fprintf(stdout, "linking failed\n");
            }

            /* draw each link */
            for (n = 0; n < nodedit->link_count; ++n) {
                struct node_link *link = &nodedit->links[n];
                struct node *ni = node_editor_find(nodedit, link->input_id);
                struct node *no = node_editor_find(nodedit, link->output_id);
                float spacei = node.bounds.h / (float)((ni->output_count) + 1);
                float spaceo = node.bounds.h / (float)((no->input_count) + 1);
                struct nk_vec2 l0 = nk_layout_space_to_screen(ctx,
                    nk_vec2(ni->bounds.x + ni->bounds.w, 3.0f + ni->bounds.y + spacei * (float)(link->input_slot+1)));
                struct nk_vec2 l1 = nk_layout_space_to_screen(ctx,
                    nk_vec2(no->bounds.x, 3.0f + no->bounds.y + spaceo * (float)(link->output_slot+1)));

                l0.x -= nodedit->scrolling.x;
                l0.y -= nodedit->scrolling.y;
                l1.x -= nodedit->scrolling.x;
                l1.y -= nodedit->scrolling.y;
                nk_stroke_curve(canvas, l0.x, l0.y, l0.x + 50.0f, l0.y,
                    l1.x - 50.0f, l1.y, l1.x, l1.y, 1.0f, nk_rgb(100, 100, 100));
            }

            if (updated) {
                /* reshuffle nodes to have least recently selected node on top */
                node_editor_pop(nodedit, updated);
                node_editor_push(nodedit, updated);
            }

            /* node selection */
            if (nk_input_mouse_clicked(in, NK_BUTTON_LEFT, nk_layout_space_bounds(ctx))) {
                it = nodedit->begin;
                nodedit->selected = NULL;
                nodedit->bounds = nk_rect(in->mouse.pos.x, in->mouse.pos.y, 100, 200);
                while (it) {
                    struct nk_rect b = nk_layout_space_rect_to_screen(ctx, it->bounds);
                    b.x -= nodedit->scrolling.x;
                    b.y -= nodedit->scrolling.y;
                    if (nk_input_is_mouse_hovering_rect(in, b))
                        nodedit->selected = it;
                    it = it->next;
                }
            }

            /* contextual menu */
            if (nk_contextual_begin(ctx, &menu, 0, nk_vec2(100, 220), nk_window_get_bounds(ctx))) {
                const char *grid_option[] = {"Show Grid", "Hide Grid"};
                nk_layout_row_dynamic(ctx, 25, 1);
                if (nk_contextual_item_label(ctx, "New", NK_TEXT_CENTERED))
                    node_editor_add(nodedit, "New", nk_rect(400, 260, 180, 220),
                            nk_rgb(255, 255, 255), 1, 2);
                if (nk_contextual_item_label(ctx, grid_option[nodedit->show_grid],NK_TEXT_CENTERED))
                    nodedit->show_grid = !nodedit->show_grid;
                nk_contextual_end(ctx);
            }
        }
        nk_layout_space_end(ctx);

        /* window content scrolling */
        if (nk_input_is_mouse_hovering_rect(in, nk_window_get_bounds(ctx)) &&
            nk_input_is_mouse_down(in, NK_BUTTON_MIDDLE)) {
            nodedit->scrolling.x += in->mouse.delta.x;
            nodedit->scrolling.y += in->mouse.delta.y;
        }
    }
    nk_end(ctx);
    return !nk_window_is_closed(ctx, "Node Editor");
}

/* ===============================================================
 *
 *                          DEVICE
 *
 * ===============================================================*/
struct device {
    struct nk_buffer cmds;
    struct nk_draw_null_texture null;
    GLuint vbo, vao, ebo;
    GLuint prog;
    GLuint vert_shdr;
    GLuint frag_shdr;
    GLint attrib_pos;
    GLint attrib_uv;
    GLint attrib_col;
    GLint uniform_tex;
    GLint uniform_proj;
    GLuint font_tex;
};

static void
device_init(struct device *dev)
{
    GLint status;
    static const GLchar *vertex_shader =
        "#version 300 es\n"
        "uniform mat4 ProjMtx;\n"
        "in vec2 Position;\n"
        "in vec2 TexCoord;\n"
        "in vec4 Color;\n"
        "out vec2 Frag_UV;\n"
        "out vec4 Frag_Color;\n"
        "void main() {\n"
        "   Frag_UV = TexCoord;\n"
        "   Frag_Color = Color;\n"
        "   gl_Position = ProjMtx * vec4(Position.xy, 0, 1);\n"
        "}\n";
    static const GLchar *fragment_shader =
        "#version 300 es\n"
        "precision mediump float;\n"
        "uniform sampler2D Texture;\n"
        "in vec2 Frag_UV;\n"
        "in vec4 Frag_Color;\n"
        "out vec4 Out_Color;\n"
        "void main(){\n"
        "   Out_Color = Frag_Color * texture(Texture, Frag_UV.st);\n"
        "}\n";

    nk_buffer_init_default(&dev->cmds);
    dev->prog = glCreateProgram();
    dev->vert_shdr = glCreateShader(GL_VERTEX_SHADER);
    dev->frag_shdr = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(dev->vert_shdr, 1, &vertex_shader, 0);
    glShaderSource(dev->frag_shdr, 1, &fragment_shader, 0);
    glCompileShader(dev->vert_shdr);
    glCompileShader(dev->frag_shdr);
    glGetShaderiv(dev->vert_shdr, GL_COMPILE_STATUS, &status);
    assert(status == GL_TRUE);
    glGetShaderiv(dev->frag_shdr, GL_COMPILE_STATUS, &status);
    assert(status == GL_TRUE);
    glAttachShader(dev->prog, dev->vert_shdr);
    glAttachShader(dev->prog, dev->frag_shdr);
    glLinkProgram(dev->prog);
    glGetProgramiv(dev->prog, GL_LINK_STATUS, &status);
    assert(status == GL_TRUE);

    dev->uniform_tex = glGetUniformLocation(dev->prog, "Texture");
    dev->uniform_proj = glGetUniformLocation(dev->prog, "ProjMtx");
    dev->attrib_pos = glGetAttribLocation(dev->prog, "Position");
    dev->attrib_uv = glGetAttribLocation(dev->prog, "TexCoord");
    dev->attrib_col = glGetAttribLocation(dev->prog, "Color");

    {
        /* buffer setup */
        GLsizei vs = sizeof(struct nk_draw_vertex);
        size_t vp = offsetof(struct nk_draw_vertex, position);
        size_t vt = offsetof(struct nk_draw_vertex, uv);
        size_t vc = offsetof(struct nk_draw_vertex, col);

        glGenBuffers(1, &dev->vbo);
        glGenBuffers(1, &dev->ebo);
        glGenVertexArrays(1, &dev->vao);

        glBindVertexArray(dev->vao);
        glBindBuffer(GL_ARRAY_BUFFER, dev->vbo);
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, dev->ebo);

        glEnableVertexAttribArray((GLuint)dev->attrib_pos);
        glEnableVertexAttribArray((GLuint)dev->attrib_uv);
        glEnableVertexAttribArray((GLuint)dev->attrib_col);

        glVertexAttribPointer((GLuint)dev->attrib_pos, 2, GL_FLOAT, GL_FALSE, vs, (void*)vp);
        glVertexAttribPointer((GLuint)dev->attrib_uv, 2, GL_FLOAT, GL_FALSE, vs, (void*)vt);
        glVertexAttribPointer((GLuint)dev->attrib_col, 4, GL_UNSIGNED_BYTE, GL_TRUE, vs, (void*)vc);
    }

    glBindTexture(GL_TEXTURE_2D, 0);
    glBindBuffer(GL_ARRAY_BUFFER, 0);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
    glBindVertexArray(0);
}

static void
device_upload_atlas(struct device *dev, const void *image, int width, int height)
{
    glGenTextures(1, &dev->font_tex);
    glBindTexture(GL_TEXTURE_2D, dev->font_tex);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, (GLsizei)width, (GLsizei)height, 0,
                GL_RGBA, GL_UNSIGNED_BYTE, image);
}

static void
device_shutdown(struct device *dev)
{
    glDetachShader(dev->prog, dev->vert_shdr);
    glDetachShader(dev->prog, dev->frag_shdr);
    glDeleteShader(dev->vert_shdr);
    glDeleteShader(dev->frag_shdr);
    glDeleteProgram(dev->prog);
    glDeleteTextures(1, &dev->font_tex);
    glDeleteBuffers(1, &dev->vbo);
    glDeleteBuffers(1, &dev->ebo);
    nk_buffer_free(&dev->cmds);
}

static void
device_draw(struct device *dev, struct nk_context *ctx, int width, int height,
    enum nk_anti_aliasing AA)
{
    GLint last_prog, last_tex;
    GLint last_ebo, last_vbo, last_vao;
    GLfloat ortho[4][4] = {
        {2.0f, 0.0f, 0.0f, 0.0f},
        {0.0f,-2.0f, 0.0f, 0.0f},
        {0.0f, 0.0f,-1.0f, 0.0f},
        {-1.0f,1.0f, 0.0f, 1.0f},
    };
    ortho[0][0] /= (GLfloat)width;
    ortho[1][1] /= (GLfloat)height;

    /* save previous opengl state */
    glGetIntegerv(GL_CURRENT_PROGRAM, &last_prog);
    glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_tex);
    glGetIntegerv(GL_ARRAY_BUFFER_BINDING, &last_vao);
    glGetIntegerv(GL_ELEMENT_ARRAY_BUFFER_BINDING, &last_ebo);
    glGetIntegerv(GL_VERTEX_ARRAY_BINDING, &last_vbo);

    /* setup global state */
    glEnable(GL_BLEND);
    glBlendEquation(GL_FUNC_ADD);
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
    glDisable(GL_CULL_FACE);
    glDisable(GL_DEPTH_TEST);
    glEnable(GL_SCISSOR_TEST);
    glActiveTexture(GL_TEXTURE0);

    /* setup program */
    glUseProgram(dev->prog);
    glUniform1i(dev->uniform_tex, 0);
    glUniformMatrix4fv(dev->uniform_proj, 1, GL_FALSE, &ortho[0][0]);
    {
        /* convert from command queue into draw list and draw to screen */
        const struct nk_draw_command *cmd;
        void *vertices, *elements;
        const nk_draw_index *offset = NULL;

        /* allocate vertex and element buffer */
        glBindVertexArray(dev->vao);
        glBindBuffer(GL_ARRAY_BUFFER, dev->vbo);
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, dev->ebo);

        glBufferData(GL_ARRAY_BUFFER, MAX_VERTEX_MEMORY, NULL, GL_STREAM_DRAW);
        glBufferData(GL_ELEMENT_ARRAY_BUFFER, MAX_ELEMENT_MEMORY, NULL, GL_STREAM_DRAW);

        /* load draw vertices & elements directly into vertex + element buffer */
        vertices = glMapBuffer(GL_ARRAY_BUFFER, GL_WRITE_ONLY);
        elements = glMapBuffer(GL_ELEMENT_ARRAY_BUFFER, GL_WRITE_ONLY);
        {
            /* fill converting configuration */
            struct nk_convert_config config;
            memset(&config, 0, sizeof(config));
            config.global_alpha = 1.0f;
            config.shape_AA = AA;
            config.line_AA = AA;
            config.circle_segment_count = 22;
            config.curve_segment_count = 22;
            config.arc_segment_count = 22;
            config.null = dev->null;

            /* setup buffers to load vertices and elements */
            {struct nk_buffer vbuf, ebuf;
            nk_buffer_init_fixed(&vbuf, vertices, MAX_VERTEX_MEMORY);
            nk_buffer_init_fixed(&ebuf, elements, MAX_ELEMENT_MEMORY);
            nk_convert(ctx, &dev->cmds, &vbuf, &ebuf, &config);}
        }
        glUnmapBuffer(GL_ARRAY_BUFFER);
        glUnmapBuffer(GL_ELEMENT_ARRAY_BUFFER);

        /* iterate over and execute each draw command */
        nk_draw_foreach(cmd, ctx, &dev->cmds) {
            if (!cmd->elem_count) continue;
            glBindTexture(GL_TEXTURE_2D, (GLuint)cmd->texture.id);
            glScissor((GLint)cmd->clip_rect.x,
                height - (GLint)(cmd->clip_rect.y + cmd->clip_rect.h),
                (GLint)cmd->clip_rect.w, (GLint)cmd->clip_rect.h);
            glDrawElements(GL_TRIANGLES, (GLsizei)cmd->elem_count, GL_UNSIGNED_SHORT, offset);
            offset += cmd->elem_count;
        }
        nk_clear(ctx);
    }

    /* restore old state */
    glUseProgram((GLuint)last_prog);
    glBindTexture(GL_TEXTURE_2D, (GLuint)last_tex);
    glBindBuffer(GL_ARRAY_BUFFER, (GLuint)last_vbo);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, (GLuint)last_ebo);
    glBindVertexArray((GLuint)last_vao);
    glDisable(GL_SCISSOR_TEST);
}


/* glfw callbacks (I don't know if there is a easier way to access text and scroll )*/
static void error_callback(int e, const char *d){printf("Error %d: %s\n", e, d);}
static void text_input(GLFWwindow *win, unsigned int codepoint)
{nk_input_unicode((struct nk_context*)glfwGetWindowUserPointer(win), codepoint);}
static void scroll_input(GLFWwindow *win, double _, double yoff)
{UNUSED(_);nk_input_scroll((struct nk_context*)glfwGetWindowUserPointer(win), (float)yoff);}

int main(int argc, char *argv[])
{
    /* Platform */
    static GLFWwindow *win;
    int width = 0, height = 0;

    /* GUI */
    struct device device;
    struct nk_context ctx;
    struct nk_font *font;
    struct nk_font_atlas atlas;
    struct node_editor node;

    /* GLFW */
    glfwSetErrorCallback(error_callback);
    if (!glfwInit()) {
        fprintf(stdout, "[GFLW] failed to init!\n");
        exit(1);
    }
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
#ifdef __APPLE__
    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
#endif
    win = glfwCreateWindow(WINDOW_WIDTH, WINDOW_HEIGHT, "Demo", NULL, NULL);
    glfwMakeContextCurrent(win);
    glfwSetWindowUserPointer(win, &ctx);
    glfwSetCharCallback(win, text_input);
    glfwSetScrollCallback(win, scroll_input);

    /* OpenGL */
    glViewport(0, 0, WINDOW_WIDTH, WINDOW_HEIGHT);
    glewExperimental = 1;
    if (glewInit() != GLEW_OK) {
        fprintf(stderr, "Failed to setup GLEW\n");
        exit(1);
    }

    {/* GUI */
    device_init(&device);
    {const void *image; int w, h;
    const char *font_path = (argc > 1) ? argv[1]: 0;
    nk_font_atlas_init_default(&atlas);
    nk_font_atlas_begin(&atlas);
    if (font_path) font = nk_font_atlas_add_from_file(&atlas, font_path, 14.0f, NULL);
    else font = nk_font_atlas_add_default(&atlas, 14.0f, NULL);
    image = nk_font_atlas_bake(&atlas, &w, &h, NK_FONT_ATLAS_RGBA32);
    device_upload_atlas(&device, image, w, h);
    nk_font_atlas_end(&atlas, nk_handle_id((int)device.font_tex), &device.null);}
    nk_init_default(&ctx, &font->handle);}

    node_editor_init(&node);
    while (!glfwWindowShouldClose(win))
    {
        /* Input */
        {double x, y;
        nk_input_begin(&ctx);
        glfwPollEvents();
        nk_input_key(&ctx, NK_KEY_DEL, glfwGetKey(win, GLFW_KEY_DELETE) == GLFW_PRESS);
        nk_input_key(&ctx, NK_KEY_ENTER, glfwGetKey(win, GLFW_KEY_ENTER) == GLFW_PRESS);
        nk_input_key(&ctx, NK_KEY_TAB, glfwGetKey(win, GLFW_KEY_TAB) == GLFW_PRESS);
        nk_input_key(&ctx, NK_KEY_BACKSPACE, glfwGetKey(win, GLFW_KEY_BACKSPACE) == GLFW_PRESS);
        nk_input_key(&ctx, NK_KEY_LEFT, glfwGetKey(win, GLFW_KEY_LEFT) == GLFW_PRESS);
        nk_input_key(&ctx, NK_KEY_RIGHT, glfwGetKey(win, GLFW_KEY_RIGHT) == GLFW_PRESS);
        nk_input_key(&ctx, NK_KEY_UP, glfwGetKey(win, GLFW_KEY_UP) == GLFW_PRESS);
        nk_input_key(&ctx, NK_KEY_DOWN, glfwGetKey(win, GLFW_KEY_DOWN) == GLFW_PRESS);
        if (glfwGetKey(win, GLFW_KEY_LEFT_CONTROL) == GLFW_PRESS ||
            glfwGetKey(win, GLFW_KEY_RIGHT_CONTROL)) {
            nk_input_key(&ctx, NK_KEY_COPY, glfwGetKey(win, GLFW_KEY_C) == GLFW_PRESS);
            nk_input_key(&ctx, NK_KEY_PASTE, glfwGetKey(win, GLFW_KEY_P) == GLFW_PRESS);
            nk_input_key(&ctx, NK_KEY_CUT, glfwGetKey(win, GLFW_KEY_X) == GLFW_PRESS);
            nk_input_key(&ctx, NK_KEY_CUT, glfwGetKey(win, GLFW_KEY_E) == GLFW_PRESS);
            nk_input_key(&ctx, NK_KEY_SHIFT, 1);
        } else {
            nk_input_key(&ctx, NK_KEY_COPY, 0);
            nk_input_key(&ctx, NK_KEY_PASTE, 0);
            nk_input_key(&ctx, NK_KEY_CUT, 0);
            nk_input_key(&ctx, NK_KEY_SHIFT, 0);
        }
        glfwGetCursorPos(win, &x, &y);
        nk_input_motion(&ctx, (int)x, (int)y);
        nk_input_button(&ctx, NK_BUTTON_LEFT, (int)x, (int)y, glfwGetMouseButton(win, GLFW_MOUSE_BUTTON_LEFT) == GLFW_PRESS);
        nk_input_button(&ctx, NK_BUTTON_MIDDLE, (int)x, (int)y, glfwGetMouseButton(win, GLFW_MOUSE_BUTTON_MIDDLE) == GLFW_PRESS);
        nk_input_button(&ctx, NK_BUTTON_RIGHT, (int)x, (int)y, glfwGetMouseButton(win, GLFW_MOUSE_BUTTON_RIGHT) == GLFW_PRESS);
        nk_input_end(&ctx);}

        /* GUI */
        if (!node_editor_run(&node, &ctx)) break;

        /* Draw */
        glfwGetWindowSize(win, &width, &height);
        glViewport(0, 0, width, height);
        glClear(GL_COLOR_BUFFER_BIT);
        glClearColor(0.2f, 0.2f, 0.2f, 1.0f);
        device_draw(&device, &ctx, width, height, NK_ANTI_ALIASING_ON);
        glfwSwapBuffers(win);
    }

    nk_font_atlas_clear(&atlas);
    nk_free(&ctx);
    device_shutdown(&device);
    glfwTerminate();
    return 0;
}