Procedure to flip raylib Y-Axis

rl_flip_y_axis.odin

import rl "vendor:raylib"

// NOTE this only works for simple shapes. Texts and Textures will be rendered upside-down

// Sets the origin to the bottom left corner with up = Y+
rl_flip_y_axis :: proc() {
  // Swap which face is culled - https://github.com/raysan5/raylib/issues/3786
  rl.rlSetCullFace(.FRONT)

  // // Option 1 - create projection matrix
  // rl.rlMatrixMode(rl.RL_PROJECTION)
  // rl.rlLoadIdentity()
  // rl.rlOrtho(0, SCREEN_WIDTH, -SCREEN_HEIGHT, 0, 0, 1) // default has SCREEN_HEIGHT as positive
  // rl.rlTranslatef(0, -SCREEN_HEIGHT, 0) // default has no translation
  // rl.rlMatrixMode(rl.RL_MODELVIEW)
  // rl.rlLoadIdentity()

  // Option 2 - create transformation matrix and use to adjust projection matrix
  transform_matrix := rl.Matrix{1, 0, 0, 0, 0, -1, -SCREEN_HEIGHT, 0, 0, 0, 1, 0, 0, 0, 0, 1}
  proj_matrix := rl.rlGetMatrixProjection()
  rl.rlSetMatrixProjection(proj_matrix * transform_matrix)
}