panopainter/engine/shape.h

#pragma once

enum class kShapeType : uint16_t
{
    Quad = const_hash("rect"),
    Poly = const_hash("poly"),
    RoundRect = const_hash("round-rect"),
    Slice9 = const_hash("slice9"),
};

namespace ui {

class Shape
{
protected:
    GLuint buffers[2]{ 0 };
    GLuint arrays[2]{ 0 };
    GLuint count[2]{ 0 };
    GLvoid* ioff[2]{ 0 };
    bool use_idx = true;
public:
    struct vertex_t { glm::vec4 pos; glm::vec2 uvs; };
    bool create_buffers(GLvoid* idx, GLvoid* vertices, int isize, int vsize);
    bool create_buffers(GLvoid* vertices, int vsize);
    void draw_fill() const;
    void draw_stroke() const;
    virtual bool create_attrib() { return true; };
    ~Shape()
    {
        glDeleteBuffers(2, buffers);
#if USE_VBO
        glDeleteVertexArrays(2, arrays);
#endif // USE_VBO
    }
protected:
    glm::vec2 quad_mid_point(glm::vec2 a, glm::vec2 b, glm::vec2 c, glm::vec2 d)
    {
        float den = (a.x-c.x)*(b.y-d.y) - (a.y-c.y)*(b.x-d.x);
        float numx = (a.x*c.y-a.y*c.x)*(b.x-d.x) - (a.x-c.x)*(b.x*d.y-b.y*d.x);
        float numy = (a.x*c.y-a.y*c.x)*(b.y-d.y) - (a.y-c.y)*(b.x*d.y-b.y*d.x);
        return glm::vec2(numx, numy) / den;
    }
    void adjust_quad_uvs(vertex_t& va, vertex_t& vb, vertex_t& vc, vertex_t& vd)
    {
        static float d[4];
        static vertex_t* v[4];
        v[0] = &va; v[1] = &vb; v[2] = &vc; v[3] = &vd;
        auto mid = quad_mid_point(va.pos, vb.pos, vc.pos, vd.pos);
        for (int i = 0; i < 4; i++)
            d[i] = glm::distance(glm::vec2(v[i]->pos), mid);
        for (int i = 0; i < 4; i++)
        {
            float q = (d[i] + d[(i + 2) % 4]) / d[(i + 2) % 4];
            v[i]->uvs = glm::vec2(v[i]->uvs) * q;
            v[i]->pos.w = q;
        }
    }
};

class LineSegment : public Shape
{
public:
    bool create()
    {
        static vertex_t vertices[2];
        count[0] = 2;
        count[1] = 2;
        ioff[0] = (GLvoid*)0;
        ioff[1] = (GLvoid*)0;
        vertices[0] = { { 0, 0, 0, 1 },{ 0, 0 } }; // A
        vertices[1] = { { 0, 0, 0, 1 },{ 0, 1 } }; // B
        return create_buffers(vertices, sizeof(vertices));
    }
    void update_vertices(const glm::vec4 data[2]);
};

class DynamicShape : public Shape
{
public:
    bool create(vertex_t* vertices = nullptr, int vcount = 0)
    {
        count[0] = vcount;
        count[1] = vcount;
        ioff[0] = (GLvoid*)0;
        ioff[1] = (GLvoid*)0;
        return create_buffers(vertices, sizeof(vertex_t) * vcount);
    }
    void update_vertices(vertex_t* vertices, int vcount);
};

class Plane : public Shape
{
    void create_impl(float w, float h, int div, GLushort* idx, vertex_t* vertices);
public:
    template<int div>
    bool create(float w, float h)
    {
        static GLushort idx[div * div * 6 + 8];
        static vertex_t vertices[(div+1)*(div+1)];
        create_impl(w, h, div, idx, vertices);
        return create_buffers(idx, vertices, sizeof(idx), sizeof(vertices));
    }
    void update_vertices(const glm::vec4* data);
/*
    bool create(att::Divisions divisions, att::Width w, att::Height h)
    {
        const int div = divisions.value;
        auto idx = std::make_unique<GLushort[]>(div * div * 6 + 8);
        auto vertices = std::make_unique<vertex_t[]>((div + 1)*(div + 1));
        create_impl(w.value, h.value, div, idx.get(), vertices.get());
        return create_buffers(idx.get(), vertices.get(), sizeof(idx), sizeof(vertices));
    }
    template<typename T>
    T get_attribute(T def_val)
    {
        auto ret = attribs.find(def_val.id);
        if (ret == attribs.end())
            return def_val;
        return *reinterpret_cast<T*>(ret->second.get());
    }
    bool create_attrib() override
    {
        const auto w = get_attribute(att::Width(0));
        const auto h = get_attribute(att::Height(0));
        const auto d = get_attribute(att::Divisions(1));
        return create(d, w, h);
    }
 */
};

class RectShape : public Shape
{
    bool create(float w, float h);
};

class Circle : public Shape
{
public:
    enum class kUVMapping: uint8_t { Planar, Tube };
    template<int div>
    bool create(float radius)
    {
        static GLushort idx[div*3 + div*2];
        static vertex_t vertices[div+1];
        create_impl(radius, div, idx, vertices);
        return create_buffers(idx, vertices, sizeof(idx), sizeof(vertices));
    }
    template<int div>
    bool create(float radius, kUVMapping map)
    {
        static GLushort idx[(div+1)*3 + (div+1)*4];
        static vertex_t vertices[(div+1)*2];
        create_impl(radius, 0.f, (div+1), idx, vertices, map);
        return create_buffers(idx, vertices, sizeof(idx), sizeof(vertices));
    }
    template<int div>
    bool create(float radius_out, float radius_in, kUVMapping map)
    {
        static GLushort idx[(div+1)*6 + (div+1)*4];
        static vertex_t vertices[(div+1) * 2];
        create_impl(radius_out, radius_in, (div+1), idx, vertices, map);
        return create_buffers(idx, vertices, sizeof(idx), sizeof(vertices));
    }
private:
    void create_impl(float radius, int div, GLushort* idx, vertex_t* vertices);
    void create_impl(float radius_out, float radius_in, int div, GLushort* idx, vertex_t* vertices, kUVMapping map);
};

class Rounded : public Shape
{
    void create_impl(float w, float h, float r, int div, GLushort* idx, GLushort* idx_tmp, vertex_t* vertices);
public:
    template<int div>
    bool create(float w, float h, float r)
    {
        static GLushort idx[(10 + div * 4) * 3 + (4 + div * 4) * 2];
        static GLushort idx_tmp[div+1];
        static vertex_t vertices[12 + (div-1) * 4];
        create_impl(w, h, r, div, idx, idx_tmp, vertices);
        return create_buffers(idx, vertices, sizeof(idx), sizeof(vertices));
    }
};

class Slice9 : public Shape
{
    void create_impl(float w, float h, float r, float tr, GLushort* idx, vertex_t* vertices);
public:
    bool create(float w, float h, float r, float tr)
    {
        static GLushort idx[3 * 3 * 6 + 4 * 2];
        static vertex_t vertices[4 * 4];
        create_impl(w, h, r, tr, idx, vertices);
        return create_buffers(idx, vertices, sizeof(idx), sizeof(vertices));
    }
};

}