terom@12: 
terom@12: #include "common.h"
terom@18: #include "render_struct.h"
terom@12: #include "render_mandelbrot.h"
terom@12: 
terom@12: #define DETAIL 255
terom@12: 
terom@12: #define absdelta(a, b) (a>b ? a-b : b-a)
terom@12: 
terom@12: int render_mandelbrot (struct render *ctx) {
terom@12:     // render algorithm vars
terom@12:     u_int32_t img_x, img_y;
terom@12:     double x0, y0, x, y, _x, _y, w_scale, h_scale;
terom@12:     u_int8_t iter;
terom@12: 
terom@12:     // calcluate the scale factors
terom@12:     w_scale = ctx->img_w/absdelta(ctx->x1, ctx->x2);
terom@12:     h_scale = ctx->img_h/absdelta(ctx->y1, ctx->y2);
terom@12:     
terom@12:     // start rendering!
terom@22:     for (img_y=ctx->img_top; img_y < ctx->img_bottom; img_y += ctx->img_y_step) {
terom@12:         // render the current row
terom@22:         for (img_x=ctx->img_left; img_x < ctx->img_right; img_x += ctx->img_x_step) {
terom@12:             x = 0;
terom@12:             y = 0;
terom@12:             x0 = img_x/w_scale + ctx->x1;
terom@12:             y0 = img_y/h_scale + ctx->y1;
terom@12:             iter = DETAIL; 
terom@12: 
terom@12:             while (x*x + y*y < (2*2) && iter > 0) {
terom@12:                 _x = x*x - y*y + x0;
terom@12:                 _y = 2*x*y + y0;
terom@12: 
terom@12:                 x = _x;
terom@12:                 y = _y;
terom@12: 
terom@12:                 iter--;
terom@12:             }
terom@12:             
terom@22:             (*ctx->local_rowbuf_addr)[img_x - ctx->img_left] = iter;
terom@12:         }
terom@12: 
terom@12:         // row cb
terom@12:         if (ctx->local_row_fn(ctx->cb_arg, (*ctx->local_rowbuf_addr)))
terom@12:             ERROR("local_row_fn");
terom@12:     }
terom@12:    
terom@12:     // return succesfully
terom@12:     return 0;
terom@12: 
terom@12: error:
terom@12:     return -1;
terom@12: }
terom@12: