src/util/geometry.c


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#include <gfx/util/geometry.h>

#include <math/vec2.h>

static void make_quad_11_positions(vec2 positions[4]) {
  positions[0] = vec2_make(-1, +1);
  positions[1] = vec2_make(-1, -1);
  positions[2] = vec2_make(+1, +1);
  positions[3] = vec2_make(+1, -1);
}

static void make_quad_01_positions(vec2 positions[4]) {
  positions[0] = vec2_make(0, 0);
  positions[1] = vec2_make(1, 0);
  positions[2] = vec2_make(1, 1);
  positions[3] = vec2_make(0, 1);
}

static GeometryDesc make_quad_desc(vec2 positions[4]) {
  GeometryDesc desc           = (GeometryDesc){0};
  desc.positions2d.data       = positions;
  desc.positions2d.size_bytes = 4 * sizeof(vec2);
  desc.num_verts              = 4;
  desc.type                   = TriangleStrip;
  return desc;
}

Geometry* gfx_make_quad_11(GfxCore* gfxcore) {
  assert(gfxcore);

  vec2 positions[4];
  make_quad_11_positions(positions);
  const GeometryDesc geometry_desc = make_quad_desc(positions);
  return gfx_make_geometry(gfxcore, &geometry_desc);
}

Geometry* gfx_make_quad_01(GfxCore* gfxcore) {
  assert(gfxcore);

  vec2 positions[4];
  make_quad_01_positions(positions);
  const GeometryDesc geometry_desc = make_quad_desc(positions);
  return gfx_make_geometry(gfxcore, &geometry_desc);
}