#version 410

uniform float yRatio; // height/width
uniform float eyePos;
uniform mat4 cameraMatrix;

in vec3 pos;
in vec3 col;

out vec3 colV; // ramped color from vertex color
out vec3 viewPosV;

// gl_Position gets final projected coordinate

// flatShader2 is a highly-reduced shader, in particular: NO PART ATTRIBUTES, so it can handle
// vast geometries ok.

void main(void)
{
    colV = col;
    
    float yRatioScaler = yRatio < 1.0 ? 1.0 : yRatio;
    float xMore = yRatio / yRatioScaler;
    float yMore = 1.0 / yRatioScaler;
    float zFixer = -150.0; // we flip & compress Z for the final depth write. Our world is all in RHS, negative Z from screen. Device is +Z.
    // matrix is actually transpose of how it "looks" here...
    mat4 projectionMatrix = mat4(xMore, 0,     0, 0,
                                 0,     yMore, 0, 0,
                                 0,     0,     1.0 / zFixer, -1.0 / eyePos,
                                 0,     0,     eyePos/ zFixer, 0);
    
    viewPosV = (cameraMatrix * vec4(pos, 1.0)).xyz;
    vec4 transformedPos = projectionMatrix * cameraMatrix * vec4(pos, 1.0);
    gl_Position = transformedPos;
}