our_dick/include/ttt/font_shader.hpp

/**
	This file is a part of our_dick
	Copyright (C) 2022 rexy712

	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU Affero General Public License as published by
	the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU Affero General Public License for more details.

	You should have received a copy of the GNU Affero General Public License
	along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#ifndef OUR_DICK_FONT_SHADER_HPP
#define OUR_DICK_FONT_SHADER_HPP

namespace font_shader{
	static constexpr char vertex_shader_text[] =
		R"glsl(
			#version 430 core
			layout (location = 0) in vec4 tex_coords;
			layout (location = 1) in vec4 color;
			layout (location = 2) in vec2 offset;
			layout (location = 3) in vec2 size;

			out VS_OUT{
				vec4 tex_coords;
				vec4 color;
				vec2 offset;
				vec2 size;
			}vs_out;

			void main(){
					vs_out.tex_coords = tex_coords;
					vs_out.color = color;
					vs_out.offset = offset;
					vs_out.size = size;
			}
		)glsl";
static constexpr char geometry_shader_text[] =
		R"glsl(
			#version 430 core
			layout (points) in;
			layout (triangle_strip, max_vertices = 4) out;

			in VS_OUT{
				vec4 tex_coords;
				vec4 color;
				vec2 offset;
				vec2 size;
			}gs_in[];

			out GS_OUT{
				vec2 tex_coords;
				flat vec4 color;
			}gs_out;

			layout (std140) uniform view_proj_matrix{
				mat4 vp_mat;
			};
			uniform vec2 start_pos;

			void main(){
				//texture coordinates need done botleft->topleft->botright->topright
				//whereas the position goes topleft->botleft->topright->botright
				//because freetype generates bitmaps with inverse y axis to opengl
				const vec4 position = vec4(gs_in[0].offset, -1, 1);
				const mat2 scaler = mat2(vp_mat[0][0], vp_mat[0][1], vp_mat[1][0], vp_mat[1][1]);

				const vec2 start_position = scaler * start_pos;
				const vec2 screen_pos = start_position + (scaler * gs_in[0].offset);
				const vec2 size = scaler * gs_in[0].size;

				const mat4 scale = vp_mat;

				const vec4 p1 = scale * vec4(gs_in[0].offset.x, gs_in[0].offset.y + gs_in[0].size.y, -1, 1);
				const vec4 p2 = scale * vec4(gs_in[0].offset, -1, 1);
				const vec4 p3 = scale * vec4(gs_in[0].offset.x + gs_in[0].size.x, gs_in[0].offset.y + gs_in[0].size.y, -1, 1);
				const vec4 p4 = scale * vec4(gs_in[0].offset.x + gs_in[0].size.x, gs_in[0].offset.y, -1, 1);

				gl_Position = p1;
				gs_out.tex_coords = gs_in[0].tex_coords.xy;
				gs_out.color = gs_in[0].color;
				EmitVertex();
				gl_Position = p2;
				gs_out.tex_coords = gs_in[0].tex_coords.xw;
				gs_out.color = gs_in[0].color;
				EmitVertex();
				gl_Position = p3;
				gs_out.tex_coords = gs_in[0].tex_coords.zy;
				gs_out.color = gs_in[0].color;
				EmitVertex();
				gl_Position = p4;
				gs_out.tex_coords = gs_in[0].tex_coords.zw;
				gs_out.color = gs_in[0].color;
				EmitVertex();

/*				gl_Position = vec4(screen_pos.x, screen_pos.y + size.y, -1.0, 1.0);
				gs_out.tex_coords = gs_in[0].tex_coords.xy;
				gs_out.color = gs_in[0].color;
				EmitVertex();

				gl_Position = vec4(screen_pos, -1.0, 1.0);
				gs_out.tex_coords = gs_in[0].tex_coords.xw;
				gs_out.color = gs_in[0].color;
				EmitVertex();

				gl_Position = vec4(screen_pos.x + size.x, screen_pos.y + size.y, -1.0, 1.0);
				gs_out.tex_coords = gs_in[0].tex_coords.zy;
				gs_out.color = gs_in[0].color;
				EmitVertex();

				gl_Position = vec4(screen_pos.x + size.x, screen_pos.y, -1.0, 1.0);
				gs_out.tex_coords = gs_in[0].tex_coords.zw;
				gs_out.color = gs_in[0].color;
				EmitVertex();
*/
				EndPrimitive();
			}
		)glsl";
static constexpr char fragment_shader_text[] =
		R"glsl(
			#version 430 core
			out vec4 frag_color;

			in GS_OUT{
				vec2 tex_coords;
				flat vec4 color;
			}fs_in;

			uniform sampler2D texture1;

			void main(){
				vec4 s = texture(texture1, fs_in.tex_coords);
				float alpha = (s.r + s.g + s.b) / 3.0;
				vec4 alpha_texture = vec4(s.rgb, alpha);
				frag_color = alpha_texture * fs_in.color; //NOT the dot product in glsl
			}
		)glsl";
}

#endif