Nuklear GLFW with older OpenGL

nuklear_glfw_gl2.c

#include <stdio.h>
#include <string.h>

#define MAX_VERTEX_BUFFER 512 * 1024
#define MAX_ELEMENT_BUFFER 128 * 1024

#define NK_IMPLEMENTATION
#include "nuklear_glfw.h"
#include "../../nuklear.h"

#define NK_GLFW_TEXT_MAX 256
struct nk_glfw_device {
    struct nk_buffer cmds;
    struct nk_draw_null_texture null;
    GLuint font_tex;
    struct nk_draw_vertex *vertices;
    nk_draw_index *elements;
};

static struct nk_glfw {
    GLFWwindow *win;
    struct nk_glfw_device ogl;
    struct nk_context ctx;
    struct nk_font_atlas atlas;
    unsigned int text[NK_GLFW_TEXT_MAX];
    int text_len;
    float scroll;
} glfw;

NK_API void
nk_glfw3_device_create(void)
{
    GLint status;

    struct nk_glfw_device *dev = &glfw.ogl;
    nk_buffer_init_default(&dev->cmds);
    dev->vertices = malloc(MAX_VERTEX_BUFFER);
    dev->elements = malloc(MAX_ELEMENT_BUFFER);
    glBindTexture(GL_TEXTURE_2D, 0);
}

NK_INTERN void
nk_glfw3_device_upload_atlas(const void *image, int width, int height)
{
    struct nk_glfw_device *dev = &glfw.ogl;
    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);
}

NK_API void
nk_glfw3_device_destroy(void)
{
    struct nk_glfw_device *dev = &glfw.ogl;
    glDeleteTextures(1, &dev->font_tex);
    free(dev->vertices);
    free(dev->elements);
    nk_buffer_free(&dev->cmds);
}

NK_API void
nk_glfw3_render(enum nk_anti_aliasing AA, int max_vertex_buffer, int max_element_buffer)
{
    struct nk_glfw_device *dev = &glfw.ogl;
    int width, height, pixelWidth, pixelHeight;
    double scaleX, scaleY;

    glfwGetWindowSize(glfw.win, &width, &height);
    /* scaling fix for Retina/High-DPI displays */
    glfwGetFramebufferSize(glfw.win, &pixelWidth, &pixelHeight);
    scaleX = (double)pixelWidth / (double)width;
    scaleY = (double)pixelHeight / (double)height;

    /* 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);
    glEnable(GL_TEXTURE_2D);
    glEnableClientState(GL_VERTEX_ARRAY);
    glEnableClientState(GL_TEXTURE_COORD_ARRAY);
    glEnableClientState(GL_COLOR_ARRAY);

    /* setup program */
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(0.0, (GLfloat)width, (GLfloat)height, 0.0, -1.0, +1.0);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    {
        /* convert from command queue into draw list and draw to screen */
        const struct nk_draw_command *cmd;
        const nk_draw_index *elemIndex = dev->elements;

        const unsigned char *ptrVert = (const unsigned char *)dev->vertices;
        GLvoid *ptrVertPos = (GLvoid *)(ptrVert + offsetof(struct nk_draw_vertex, position));
        GLvoid *ptrVertTex = (GLvoid *)(ptrVert + offsetof(struct nk_draw_vertex, uv));
        GLvoid *ptrVertCol = (GLvoid *)(ptrVert + offsetof(struct nk_draw_vertex, col));

        {
            /* 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, dev->vertices, (size_t)max_vertex_buffer);
            nk_buffer_init_fixed(&ebuf, dev->elements, (size_t)max_element_buffer);
            nk_convert(&glfw.ctx, &dev->cmds, &vbuf, &ebuf, &config);}
        }

        glVertexPointer  (2, GL_FLOAT,         sizeof(struct nk_draw_vertex), ptrVertPos);
        glTexCoordPointer(2, GL_FLOAT,         sizeof(struct nk_draw_vertex), ptrVertTex);
        glColorPointer   (4, GL_UNSIGNED_BYTE, sizeof(struct nk_draw_vertex), ptrVertCol);

        /* iterate over and execute each draw command */
        nk_draw_foreach(cmd, &glfw.ctx, &dev->cmds) {
            if (!cmd->elem_count) continue;

            glBindTexture(GL_TEXTURE_2D, (GLuint)cmd->texture.id);
            glScissor((GLint)((double)cmd->clip_rect.x * scaleX),
                (GLint)((double)(height - (GLint)(cmd->clip_rect.y + cmd->clip_rect.h)) * scaleY),
                (GLint)((double)cmd->clip_rect.w * scaleX), (GLint)((double)cmd->clip_rect.h * scaleY));
            glDrawElements(GL_TRIANGLES, (GLsizei)cmd->elem_count, GL_UNSIGNED_SHORT, elemIndex);
            elemIndex += cmd->elem_count;
        }
        nk_clear(&glfw.ctx);
    }

    /* restore old state */
    glDisable(GL_SCISSOR_TEST);
    glDisableClientState(GL_VERTEX_ARRAY);
    glDisableClientState(GL_TEXTURE_COORD_ARRAY);
    glDisableClientState(GL_COLOR_ARRAY);
    glDisable(GL_TEXTURE_2D);
}

NK_API void
nk_glfw3_char_callback(GLFWwindow *win, unsigned int codepoint)
{
    (void)win;
    if (glfw.text_len < NK_GLFW_TEXT_MAX)
        glfw.text[glfw.text_len++] = codepoint;
}

NK_API void
nk_gflw3_scroll_callback(GLFWwindow *win, double xoff, double yoff)
{
    (void)win; (void)xoff;
    glfw.scroll += (float)yoff;
}

static void
nk_glfw3_clipbard_paste(nk_handle usr, struct nk_text_edit *edit)
{
    const char *text = glfwGetClipboardString(glfw.win);
    if (text) nk_textedit_paste(edit, text, nk_strlen(text));
    (void)usr;
}

static void
nk_glfw3_clipbard_copy(nk_handle usr, const char *text, int len)
{
    char *str = 0;
    (void)usr;
    if (!len) return;
    str = malloc((size_t)len+1);
    if (!str) return;
    memcpy(str, text, (size_t)len);
    str[len] = '\0';
    glfwSetClipboardString(glfw.win, str);
    free(str);
}

NK_API struct nk_context*
nk_glfw3_init(GLFWwindow *win, enum nk_glfw_init_state init_state)
{
    glfw.win = win;
    if (init_state == NK_GLFW3_INSTALL_CALLBACKS) {
        glfwSetScrollCallback(win, nk_gflw3_scroll_callback);
        glfwSetCharCallback(win, nk_glfw3_char_callback);
    }

    nk_init_default(&glfw.ctx, 0);
    glfw.ctx.clip.copy = nk_glfw3_clipbard_copy;
    glfw.ctx.clip.paste = nk_glfw3_clipbard_paste;
    glfw.ctx.clip.userdata = nk_handle_ptr(0);
    nk_glfw3_device_create();
    return &glfw.ctx;
}

NK_API void
nk_glfw3_font_stash_begin(struct nk_font_atlas **atlas)
{
    nk_font_atlas_init_default(&glfw.atlas);
    nk_font_atlas_begin(&glfw.atlas);
    *atlas = &glfw.atlas;
}

NK_API void
nk_glfw3_font_stash_end(void)
{
    const void *image; int w, h;
    image = nk_font_atlas_bake(&glfw.atlas, &w, &h, NK_FONT_ATLAS_RGBA32);
    nk_glfw3_device_upload_atlas(image, w, h);
    nk_font_atlas_end(&glfw.atlas, nk_handle_id((int)glfw.ogl.font_tex), &glfw.ogl.null);
    if (glfw.atlas.default_font)
        nk_style_set_font(&glfw.ctx, &glfw.atlas.default_font->handle);
}

NK_API void
nk_glfw3_new_frame(void)
{
    int i;
    double x, y;
    struct nk_context *ctx = &glfw.ctx;
    struct GLFWwindow *win = glfw.win;
    nk_input_begin(ctx);
    for (i = 0; i < glfw.text_len; ++i)
        nk_input_unicode(ctx, glfw.text[i]);

    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_UP, glfwGetKey(win, GLFW_KEY_UP) == GLFW_PRESS);
    nk_input_key(ctx, NK_KEY_DOWN, glfwGetKey(win, GLFW_KEY_DOWN) == GLFW_PRESS);
    nk_input_key(ctx, NK_KEY_TEXT_START, glfwGetKey(win, GLFW_KEY_HOME) == GLFW_PRESS);
    nk_input_key(ctx, NK_KEY_TEXT_END, glfwGetKey(win, GLFW_KEY_END) == GLFW_PRESS);
    nk_input_key(ctx, NK_KEY_SHIFT, glfwGetKey(win, GLFW_KEY_LEFT_SHIFT) == GLFW_PRESS||
                                    glfwGetKey(win, GLFW_KEY_RIGHT_SHIFT) == 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_TEXT_UNDO, glfwGetKey(win, GLFW_KEY_Z) == GLFW_PRESS);
        nk_input_key(ctx, NK_KEY_TEXT_REDO, glfwGetKey(win, GLFW_KEY_R) == GLFW_PRESS);
        nk_input_key(ctx, NK_KEY_TEXT_WORD_LEFT, glfwGetKey(win, GLFW_KEY_LEFT) == GLFW_PRESS);
        nk_input_key(ctx, NK_KEY_TEXT_WORD_RIGHT, glfwGetKey(win, GLFW_KEY_RIGHT) == GLFW_PRESS);
        nk_input_key(ctx, NK_KEY_TEXT_LINE_START, glfwGetKey(win, GLFW_KEY_B) == GLFW_PRESS);
        nk_input_key(ctx, NK_KEY_TEXT_LINE_END, glfwGetKey(win, GLFW_KEY_E) == GLFW_PRESS);
    } else {
        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_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_scroll(ctx, glfw.scroll);
    nk_input_end(&glfw.ctx);

    glfw.text_len = 0;
    glfw.scroll = 0;
}

NK_API
void nk_glfw3_shutdown(void)
{
    nk_font_atlas_clear(&glfw.atlas);
    nk_free(&glfw.ctx);
    nk_glfw3_device_destroy();
}