image.jl

using ModernGL, GLWindow, GLUtil, React, ImmutableArrays
const window = createwindow("Example", 512, 512)

window_size = window.inputs[:window_size]
w,h = window_size.value # get initial window size
#Resize glviewport, when window size changes.
lift(window_size -> glViewport(0,0, window_size[1], window_size[2]), window_size)

const vsh = """
in vec2 position;
out vec2 uv;
void main() {
	uv = (position + vec2(1)) / vec2(2); //texture coordinates are between 0-1
	gl_Position = vec4(position, 0.0, 1.0);
}
"""
 
const fsh = """
in vec2 uv;
uniform sampler2D image;

out vec4 fragment_color;

void main() {
	fragment_color = texture(image, uv);
}
"""


imgdata = [Vector4(0f0) for x=1:w, y=1:h]
image = Texture(imgdata)
imgdata = 0
const fullscreenquad = RenderObject(
	[
		:position 	=> GLBuffer(GLfloat[-1,-1, -1,1, 1,1, 1,1, 1,-1, -1,-1], 2), 
		:image 		=> image
	], GLProgram(vsh, fsh, "vertexshader", "fragmentshader"))
prerender!(fullscreenquad, render, fullscreenquad.vertexarray)

global t = 0
function calculation()
	global t
	w,h = window_size.value # get current window size
	data = [Vector4(float32(x/w), float32(y/h), float32(0.5 * (1 + sin(t * 0.2))), 1f0) for x=1:w, y=1:h]
	t += 1
	glBindTexture(GL_TEXTURE_2D, image.id)
	glTexSubImage2D(GL_TEXTURE_2D, 0, 0,0 , w,h, image.format, image.pixeltype, data)
	data = 0
end

while !GLFW.WindowShouldClose(window.glfwWindow)   
    glClearColor(0.0, 0.0,0.0, 1.0)
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)

	calculation()

	render(fullscreenquad)
 	
    # Swap front and back buffers
 	GLFW.SwapBuffers(window.glfwWindow)
    # Poll for and process events
    GLFW.PollEvents()
end
 
GLFW.Terminate()