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#include "common.h"

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#include "render_struct.h"

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#include "render_mandelbrot.h"

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#define DETAIL 255

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#define absdelta(a, b) (a>b ? a-b : b-a)

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int render_mandelbrot (struct render *ctx) {

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    // render algorithm vars

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    u_int32_t img_x, img_y;

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    double x0, y0, x, y, _x, _y, w_scale, h_scale;

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    u_int8_t iter;

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    // calcluate the scale factors

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    w_scale = ctx->img_w/absdelta(ctx->x1, ctx->x2);

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    h_scale = ctx->img_h/absdelta(ctx->y1, ctx->y2);

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    // start rendering!

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    for (img_y=ctx->img_top; img_y < ctx->img_bottom; img_y += ctx->img_y_step) {

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        // render the current row

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        for (img_x=ctx->img_left; img_x < ctx->img_right; img_x += ctx->img_x_step) {

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            x = 0;

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            y = 0;

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            x0 = img_x/w_scale + ctx->x1;

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            y0 = img_y/h_scale + ctx->y1;

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            iter = DETAIL; 

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            while (x*x + y*y < (2*2) && iter > 0) {

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                _x = x*x - y*y + x0;

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                _y = 2*x*y + y0;

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                x = _x;

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                y = _y;

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                iter--;

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            }

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            (*ctx->local_rowbuf_addr)[img_x - ctx->img_left] = iter;

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        }

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        // row cb

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        if (ctx->local_row_fn(ctx->cb_arg, (*ctx->local_rowbuf_addr)))

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            ERROR("local_row_fn");

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    }

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    // return succesfully

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    return 0;

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error:

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    return -1;

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}

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