spring-dev

function widget:GetInfo()
	return {
		name      = "skin",
		desc      = "skin",
		author    = "ivand",
		license   = "GNU GPL, v2 or later",
		layer     = 0,
		enabled   = true --  loaded by default?
	}
end


local shader
local viewMatLoc, projMatLoc

local vao

local shaderSrc = {
	vs =
[[
#version 410 core
#extension GL_ARB_explicit_attrib_location : enable
// defines
#define VA_TYPE VA_TYPE_L

// globals
// uniforms
uniform mat4 u_movi_mat;
uniform mat4 u_proj_mat;

// VS input attributes
layout(location = 0) in vec4 a_vertex_xyzw;
layout(location = 1) in vec3 a_normal_xyz;
layout(location = 2) in vec2 a_texcoor_stuv;
layout(location = 3) in vec4 a_color0_rgba;
layout(location = 4) in vec4 a_color1_rgba;
// VS output attributes
 out vec4 v_vertex_xyzw;
 out vec3 v_normal_xyz;
 out vec2 v_texcoor_stuv;
 out vec4 v_color0_rgba;
 out vec4 v_color1_rgba;

void main() {
	gl_Position = u_proj_mat * u_movi_mat * vec4(a_vertex_xyzw);
	v_vertex_xyzw = a_vertex_xyzw;
	v_normal_xyz = a_normal_xyz;
	v_texcoor_stuv = a_texcoor_stuv;
	v_texcoor_stuv.y = 1.0 - v_texcoor_stuv.y;
	v_color0_rgba = a_color0_rgba;
	v_color1_rgba = a_color1_rgba;
}
]],
	fs =
[[
#version 410 core
#extension GL_ARB_explicit_attrib_location : enable
// defines
#define VA_TYPE VA_TYPE_L

// globals
// uniforms
uniform sampler2D u_tex0;
uniform vec4 u_alpha_test_ctrl = vec4(0.0, 0.0, 0.0, 1.0);
uniform vec3 u_gamma_exponents = vec3(1.0, 1.0, 1.0);
uniform float u_tex_loaded = 1.0;

// FS input attributes
 in vec4 v_vertex_xyzw;
 in vec3 v_normal_xyz;
 in vec2 v_texcoor_stuv;
 in vec4 v_color0_rgba;
 in vec4 v_color1_rgba;
// FS output attributes
layout(location = 0) out vec4 f_color_rgba;

void main() {
	f_color_rgba  = mix(vec4(1.0), texture(u_tex0, v_texcoor_stuv.st), u_tex_loaded);
	f_color_rgba *= v_color0_rgba * (1.0 / 255.0);

	float alpha_test_gt = float(f_color_rgba.a > u_alpha_test_ctrl.x) * u_alpha_test_ctrl.y;
	float alpha_test_lt = float(f_color_rgba.a < u_alpha_test_ctrl.x) * u_alpha_test_ctrl.z;
	if ((alpha_test_gt + alpha_test_lt + u_alpha_test_ctrl.w) == 0.0)
		discard;
	f_color_rgba.rgb = pow(f_color_rgba.rgb, u_gamma_exponents);
}
]]
}

local function CreateStretchedPlaneVAO(lrRatio, tbRatio)
	--[[

	Plane 4 x 4 vertices

	* * * *
	* * * *
	* * * *
	* * * *

	draw with quads for simplicity
	every quad requires 2 triangles ==> 6 indices
	9 quads in the plane

	]]--
	local vao = gl.CreateVertexArray(4 * 4, 9 * 6, false)

	local verts = {
		p  = {
			-1.0, -1.0, 0, 1,		-0.5, -1.0, 0, 1,		0.5, -1.0, 0, 1,		1.0, -1.0, 0, 1,
			-1.0, -0.5, 0, 1,		-0.5, -0.5, 0, 1,		0.5, -0.5, 0, 1,		1.0, -0.5, 0, 1,
			-1.0,  0.5, 0, 1,		-0.5,  0.5, 0, 1,		0.5,  0.5, 0, 1,		1.0,  0.5, 0, 1,
			-1.0,  1.0, 0, 1,		-0.5,  1.0, 0, 1,		0.5,  1.0, 0, 1,		1.0,  1.0, 0, 1,
		}, --each point is defined by 4 coordinates (xyzw)
		c0 = {
			1, 1, 1, 1,			1, 1, 1, 1, 		1, 1, 1, 1,			1, 1, 1, 1,
			1, 1, 1, 1,			1, 1, 1, 1, 		1, 1, 1, 1,			1, 1, 1, 1,
			1, 1, 1, 1,			1, 1, 1, 1, 		1, 1, 1, 1,			1, 1, 1, 1,
			1, 1, 1, 1,			1, 1, 1, 1, 		1, 1, 1, 1,			1, 1, 1, 1,
		},
		uv = {
			0, 0, 0, 0,					lrRatio, 0, 0, 0,					1 - lrRatio, 0, 0, 0,					1, 0, 0, 0,
			0, tbRatio, 0, 0,			lrRatio, tbRatio, 0, 0,				1 - lrRatio, tbRatio, 0, 0,				1, tbRatio, 0, 0,
			0, 1 - tbRatio, 0, 0,		lrRatio, 1 - tbRatio, 0, 0,			1 - lrRatio, 1 - tbRatio, 0, 0,			1, 1 - tbRatio, 0, 0,
			0, 1, 0, 0,					lrRatio, 1, 0, 0,					1 - lrRatio, 1, 0, 0,					1, 1, 0, 0,
		}, --uv coordinates. 4 tuple, with trailing two == 0 (only first two are used)
		i = {
			0, 1, 4, 1, 5, 4,		1, 2, 5, 2, 6, 5, 		2, 3, 6, 3, 7, 6,
			4, 5, 8, 5, 9, 8,		5, 6, 9, 6, 10, 9,		6, 7, 10, 7, 11, 10,
			8, 9, 12, 9, 13, 12,	9, 10, 13, 10, 14, 13,	10, 11, 14, 11, 15, 14,
		}, --indices forming triangles of quads
	}
	
	for i = 0, 15 do
		verts.p[4*i + 1] = verts.p[4*i + 1] * 0.5
		verts.p[4*i + 2] = verts.p[4*i + 2] * 0.5
	end

	-- 0, 0 relative indices to start of vertex and index arrays. Non-zero indices allow for partial VAO update
	gl.UpdateVertexArray(vao, 0, 0, verts)

	return vao
end


function widget:DrawScreen()
	if not shader then
		return
	end
	--Spring.Echo("BLABLABLA")
	--TODO do it once per ...
	gl.Texture(0, "LuaUI/Widgets/uvtemplate002-lg.jpg")
	gl.UseShader(shader)
	gl.UniformMatrix(viewMatLoc, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1)
	gl.UniformMatrix(projMatLoc, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1)	
	if vao then
		--Spring.Echo("BLABLABLA")
		--render as triangles
		gl.RenderVertexArray(vao, GL.TRIANGLES) --skip optional arguments for simplicity
	end

	gl.UseShader(0)
	gl.Texture(0, false)
end


function widget:Initialize()
	-- VA_TYPE_T (attributes: p(xyzw), st)
	--local shaderSrc = gl.GetDefaultShaderSources("VA_TYPE_TC")
	shader = gl.CreateShader({
		vertex = shaderSrc.vs,
		fragment = shaderSrc.fs,
		uniformInt = {
			u_tex0 = 0,
		}
	})

	viewMatLoc = gl.GetUniformLocation(shader, "u_movi_mat")
	projMatLoc = gl.GetUniformLocation(shader, "u_proj_mat")

--[[	
	gl.UseShader(shader)
	gl.UniformMatrix(viewMatLoc, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1)
	gl.UniformMatrix(projMatLoc, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1)
	gl.UseShader(0)
]]--

	vao = CreateStretchedPlaneVAO(0.1, 0.1)
	Spring.Echo("shader", shader, "vao", vao)
end

function widget:Finalize()
	if shader then gl.DeleteShader(shader) end
	if vao then gl.DeleteVertexArray(vao) end
end