Repository

SciGL.jl

Port of scigl_render to julia.

The primary goal is to enable efficient rendering of multiple scenes and transferring the images to a compute device (CPU or CUDA) for Scientific calculations.

This is achieved by rendering to different layers of a 3D texture (width, height, depth) via glFramebufferTextureLayer. Pixel pack buffer objects are used to transfer data from OpenGL to the CPU or CUDA. Have a look at OffscreenContext which provides a simple interface for rendering and transferring the data.

Conventions

Camera and image conventions

The OpenCV camera uses the OpenCV conventions which means:

  • X: right
  • Y: down (OpenGL up)
  • Z: forward (OpenGL backward)

Moreover, the resulting images have the origin in the top-left compared to the bottom-left in OpenGL. Consequently, renderings appear upside down in OpenGL context windows but upright in memory, e.g. when copying from textures to CPU or CUDA arrays.

Shader naming conventions

Uniforms:

  • mat4 model_matrix: affine transformation matrix to transform model to world coordinates
  • mat4 view_matrix: affine transformation matrix to transform world to view coordinates
  • mat4 projection_matrix: perspective transformation matrix from view to clip coordinates

Warning all matrix and vector uniforms must be StaticArrays of type Float32

Vertex Shader Inputs:

  • vec3 position: vertex position in model coordinates
  • vec3 normal: vertex normal in model coordinates
  • vec3 color: vertex color in model coordinates

Fragment Shader Inputs:

  • vec3 model_color: color of the fragment
  • vec3 model_normal: normal vector of the fragment in model coordinates
  • vec4 model_position: position vector of the fragment in model coordinates
  • vec3 view_normal: normal vector of the fragment in view coordinates
  • vec4 view_position: position vector of the fragment in view coordinates
  • vec3 world_normal: normal vector of the fragment in world coordinates
  • vec4 world_position: position of the fragment in world coordinates

Example meshes

In examples/meshes you can find two meshes:

  • cube.obj is a simple cube of size (1,1,1) meter.
  • monkey.obj is the Blender Suzanne with Z pointing up and the face pointing in X direction. Size is (0.632, 1, 0.72) meters.