spritebatch.cc

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#include "render/spritebatch.h"
#include "render/gl.h"
 
#include "assert/assert.h"
#include "base/cint.h"
 
namespace eu::render
{
    // vertex + uv + color
    constexpr int quad_cont = 10;
    constexpr int stride = 2 * 4 + 2 * 4 + 4 * 4;
 
 
    SpriteBatch::SpriteBatch() : is_inside(false), current_quad_count(0), number_of_render_calls(0)
    {
        vertex_data.reserve(c_int_to_sizet(stride * quad_cont));
        quad_indices.reserve(c_int_to_sizet(6 * quad_cont));
    }
 
 
    SpriteBatch::~SpriteBatch() = default;
 
 
    void
    SpriteBatch::begin()
    {
        ASSERT(!is_inside && "Already open, missing call to end.");
        number_of_render_calls = 0;
    }
 
 
    void
    SpriteBatch::render_quad
    (
        const vec2f& pos,
        const size2f& quad,
        const Rectf& uv,
        const Scale2f& center,
        const Angle& rotation,
        const Rgba& color
    )
    {
        ASSERT(is_inside && "batch need to be open");
 
        if((current_quad_count + 1) >= quad_cont)
        {
            flush();
        }
 
        // add vertices
        const float w = quad.width;
        const float h = quad.height;
        const float sy = -sin(rotation);
        const float left = pos.x + (-center.x * w) * sy;
        const float right = pos.x + (-center.x * w + w) * sy;
        const float top = pos.y + (-center.y * h) * sy;
        const float bottom = pos.y + (-center.y * h + h) * sy;
        const auto upper_left = vec2f(left, top);
        const auto upper_right = vec2f(right, top);
        const auto lower_left = vec2f(left, bottom);
        const auto lower_right = vec2f(right, bottom);
 
        vertex_data.push_back(upper_left.x);
        vertex_data.push_back(upper_left.y);
 
        vertex_data.push_back(upper_right.x);
        vertex_data.push_back(upper_right.y);
 
        vertex_data.push_back(lower_right.x);
        vertex_data.push_back(lower_right.y);
 
        vertex_data.push_back(lower_left.x);
        vertex_data.push_back(lower_left.y);
 
        // add uv coordinate
        vertex_data.push_back(uv.left);
        vertex_data.push_back(uv.top);
        vertex_data.push_back(uv.right);
        vertex_data.push_back(uv.top);
        vertex_data.push_back(uv.right);
        vertex_data.push_back(uv.bottom);
        vertex_data.push_back(uv.left);
        vertex_data.push_back(uv.bottom);
 
        // add color
        for(int color_counter = 0; color_counter < 4; color_counter += 1)
        {
            vertex_data.push_back(color.r);
            vertex_data.push_back(color.g);
            vertex_data.push_back(color.b);
            vertex_data.push_back(color.a);
        }
 
        // add index
        int start = current_quad_count * 4;
 
        quad_indices.push_back(start + 0);
        quad_indices.push_back(start + 1);
        quad_indices.push_back(start + 2);
 
        quad_indices.push_back(start + 0);
        quad_indices.push_back(start + 2);
        quad_indices.push_back(start + 3);
 
        current_quad_count += 1;
    }
 
 
    void
    SpriteBatch::end()
    {
        ASSERT(is_inside && "not open, missing begin.");
        flush();
        is_inside = false;
    }
 
 
    void
    SpriteBatch::flush()
    {
        if(current_quad_count == 0)
        {
            return;
        }
        // todo(Gustav): build vbo & render vbo
        // remove all items
        current_quad_count = 0;
        vertex_data.resize(0);
        number_of_render_calls += 1;
    }
}