feat(shaders): Implement FBO capture lifecycle in ShaderManager

src/shader_manager.py

@@ -6,6 +6,38 @@ class ShaderManager:
   self.bg_program = None
   self.pp_program = None
   self.blur_program = None
+  self.capture_fbo = None
+  self.capture_tex = None
+  self.fbo_width = 0
+  self.fbo_height = 0
+
+ def setup_capture_fbo(self, width, height):
+  if self.capture_fbo is not None:
+   gl.glDeleteFramebuffers(1, [self.capture_fbo])
+  if self.capture_tex is not None:
+   gl.glDeleteTextures(1, [self.capture_tex])
+  self.capture_fbo = gl.glGenFramebuffers(1)
+  self.capture_tex = gl.glGenTextures(1)
+  gl.glBindTexture(gl.GL_TEXTURE_2D, self.capture_tex)
+  gl.glTexImage2D(gl.GL_TEXTURE_2D, 0, gl.GL_RGBA, width, height, 0, gl.GL_RGBA, gl.GL_UNSIGNED_BYTE, None)
+  gl.glTexParameteri(gl.GL_TEXTURE_2D, gl.GL_TEXTURE_MIN_FILTER, gl.GL_LINEAR)
+  gl.glTexParameteri(gl.GL_TEXTURE_2D, gl.GL_TEXTURE_MAG_FILTER, gl.GL_LINEAR)
+  gl.glBindFramebuffer(gl.GL_FRAMEBUFFER, self.capture_fbo)
+  gl.glFramebufferTexture2D(gl.GL_FRAMEBUFFER, gl.GL_COLOR_ATTACHMENT0, gl.GL_TEXTURE_2D, self.capture_tex, 0)
+  if gl.glCheckFramebufferStatus(gl.GL_FRAMEBUFFER) != gl.GL_FRAMEBUFFER_COMPLETE:
+   raise RuntimeError("Framebuffer not complete")
+  gl.glBindFramebuffer(gl.GL_FRAMEBUFFER, 0)
+  self.fbo_width = width
+  self.fbo_height = height
+
+ def capture_begin(self, width, height):
+  if self.capture_fbo is None or self.fbo_width != width or self.fbo_height != height:
+   self.setup_capture_fbo(width, height)
+  gl.glBindFramebuffer(gl.GL_FRAMEBUFFER, self.capture_fbo)
+  gl.glViewport(0, 0, width, height)
+
+ def capture_end(self):
+  gl.glBindFramebuffer(gl.GL_FRAMEBUFFER, 0)
 
  def compile_shader(self, vertex_src: str, fragment_src: str) -> int:
   program = gl.glCreateProgram()