A 2D texture that supports drawing to itself via Blit calls. A 2D texture that can be modified via blit calls, copying from a target texture to itself. Primarily intended to be managed in code, a user must call [method setup] to initialize the state before drawing. Each [method blit_rect] call takes at least a rectangle, the area to draw to, and another texture, what to be drawn. The draw calls use a Texture_Blit Shader to process and calculate the result, pixel by pixel. Users can supply their own ShaderMaterial with custom Texture_Blit shaders for more complex behaviors. Draws to given [param rect] on this texture by copying from the given [param source]. A [param modulate] color can be passed in for the shader to use, but defaults to White. The [param mipmap] value can specify a draw to a lower mipmap level. The [param material] parameter can take a ShaderMaterial with a TextureBlit Shader for custom drawing behavior. Draws to the given [param rect] on this texture, as well as on up to 3 DrawableTexture [param extra_targets]. All [param extra_targets] must be the same size and DrawableFormat as the original target, otherwise the Shader may fail. Expects up to 4 Texture [param sources], but will replace missing [param sources] with default Black Textures. Re-calculates the mipmaps for this texture on demand. Returns [code]true[/code] if mipmaps are set to be used on this DrawableTexture. Sets the format of this DrawableTexture. Sets the height of this DrawableTexture. Sets if mipmaps should be used on this DrawableTexture. Sets the width of this DrawableTexture. Initializes the DrawableTexture to a White texture of the given [param width], [param height], and [param format]. OpenGL texture format RGBA with four components, each with a bitdepth of 8. OpenGL texture format RGBA with four components, each with a bitdepth of 8. When drawn to, an sRGB to linear color space conversion is performed. OpenGL texture format GL_RGBA16F where there are four components, each a 16-bit "half-precision" floating-point value. OpenGL texture format GL_RGBA32F where there are four components, each a 32-bit floating-point value.