Software Renderer – Tech Demo

I’ve built projects with OpenGL before, specifically the custom Game Engine. However, I never quite understood the math behind turning vertices into pixels on the screen.

Out of curiosity, I’ve built a software renderer and it proved to be a real eye-opener into the world of 3D graphics programming.

It may be obvious, but I realized that: We are always looking at a flat screen, the illusion of a 3D world sustains because the right pixels are drawn in the correct places.

It’s crazy when you think about it – we stare into these flat screens for hours on end. Games really do take place in our minds.

It was based mostly on this tutorial by thebennybox. I’ve written it in C++ with SFML as a starting point.

Sample Code

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class Instance {
public:
    Instance(const Mesh& mesh, const Bitmap& texture) :
        mesh(mesh),
        texture(texture) {
    }
    void render(RenderContext& target, Matrix4 vp) {
        target.drawMesh(mesh, vp, transform, texture);
    }

    const Mesh&   mesh;
    const Bitmap& texture;
    Matrix4       transform;
};

int main() {
    RenderContext context(1080 / scale, 720 / scale);
    Display display(context, scale);

    Matrix4 projection;
    projection.perspective(90.0f, 800.0f/600.0f, 0.1f, 100.0f);

    Mesh marioMesh("assets/mario.obj");
    Bitmap marioTexture = Bitmap::LoadFromFile("assets/mario.png");
    Instance mario (marioMesh, marioTexture);

    while(display.isOpen()) {
        mario.render(context, viewProjection);
    }
}

Code Repository

Video

Image used from Evas GL Programming Guide