main.vs.glsl

#version 150

in vec2 vertex;
out vec4 vert_color;
out vec2 vert_texcoords;

uniform vec4 texcoords;
uniform vec4 color;
uniform vec2 scale;
uniform vec2 position;
uniform vec2 window;

void main() {
    vec2 worldspace_size = vec2(4.0, 3.0);
    // TODO make work when window aspect ratio < worldspace aspect ratio
    vec2 worldspace_origin = vec2(
            (0.9*window.y*worldspace_size.x/worldspace_size.y)/window.x,
            0.9) * -1.0;
    vec2 worldspace_scale = (worldspace_origin * -2.0)/worldspace_size;
    vec2 out_vert = vertex * scale;
    out_vert += position;
    out_vert *= worldspace_scale;
    out_vert += worldspace_origin;
    gl_Position = vec4(out_vert, 0.0, 1.0);
    vert_color = color;
    //this is the hackiest thing in a long time
    vert_texcoords = vec2(texcoords.x + (texcoords.z*(vertex.x + 0.5)), texcoords.y + (texcoords.w*(1.0 - (vertex.y + 0.5))));
}