Texture scaling

1 files changed, 51 insertions, 57 deletions

diff --git a/src/render.zig b/src/render.zig
index 27bd0cc..f81ce4f 100644
--- a/src/render.zig
+++ b/src/render.zig
@@ -71,7 +71,7 @@ fn fasterColourBlend(onto: Colour, from: Colour) Colour {
 
 const LocalCoordHit = struct {
     local_dist: f32,
-    frac: f32,
+    texture_frac: f32,
 };
 
 // The primary observation is: if a line segment AB disconnects the unit square,
@@ -132,11 +132,14 @@ fn hitDistLocalCoords(
                 // indexes it along vp->v which we use for texture mapping.
                 const denom = (rdx * vdy - vdx * rdy);
                 const t = (vdx * (ray0_y - vp[1]) - vdy * (ray0_x - vp[0])) / denom;
-                const frac = crossp / denom;
+                const side_frac = crossp / denom;
                 const new_distance = rdist * t;
 
                 if (ret_val == null or (new_distance < ret_val.?.local_dist)) {
-                    ret_val = LocalCoordHit{ .local_dist = new_distance, .frac = frac };
+                    ret_val = LocalCoordHit{
+                        .local_dist = new_distance,
+                        .texture_frac = (side_frac + @intToFloat(f32, i - 1)) / @intToFloat(f32, vertices.len),
+                    };
                 }
             }
         }
@@ -434,10 +437,11 @@ pub fn Renderer(PlaneWidth: f32, PlaneHeight: f32) type {
                             ray1_y = std.math.modf(next_distance * sinra + ppos_y).fpart;
                         }
 
+                        var previous_layer_height: f32 = 0;
                         for (cell.lower_layers.constSlice()) |layer| {
-                            if (hitDistLocalCoords(ray0_x, ray0_y, ray1_x, ray1_y, layer.vertices.constSlice())) |dist_frac| {
+                            if (hitDistLocalCoords(ray0_x, ray0_y, ray1_x, ray1_y, layer.vertices.constSlice())) |hit| {
                                 // TODO: Correct for fisheye?
-                                const adj_distance = distance + dist_frac.local_dist;
+                                const adj_distance = distance + hit.local_dist;
 
                                 // project the top of the bottom and the bottom of the top
                                 top_of_floor = PlaneHeight / 2 + PlaneDist * (layer.height - pheight) / adj_distance;
@@ -448,7 +452,8 @@ pub fn Renderer(PlaneWidth: f32, PlaneHeight: f32) type {
 
                                 // Are we able to see any vertical faces?
                                 if (draw_lower) {
-                                    const texstrip = @floatToInt(c_uint, constants.TextureDim * dist_frac.frac);
+                                    const tex_strip = std.math.modf(layer.vertical_texture_scale * hit.texture_frac).fpart;
+                                    const texcol = @floatToInt(c_uint, constants.TextureDim * tex_strip);
 
                                     // height of a unit-height wall at this distance
                                     const nominal_length = PlaneDist / adj_distance;
@@ -461,7 +466,7 @@ pub fn Renderer(PlaneWidth: f32, PlaneHeight: f32) type {
                                         const t_lower_off = layer.vertical_texture * td;
                                         // Note the bizarre rounding we have to do to avoid artifacts
                                         const constrained_top = std.math.floor(std.math.min(top_of_floor, lowest_drawn));
-                                        const proj_height = layer.height * nominal_length;
+                                        const proj_height = (layer.height - previous_layer_height) * nominal_length;
                                         const constrained_bottom = std.math.max(highest_drawn, top_of_floor - proj_height);
                                         const stop = @floatToInt(usize, PlaneWidth * (PlaneHeight - constrained_bottom)) + col;
                                         const pix_y = @floatToInt(usize, std.math.ceil(std.math.max(PlaneHeight - constrained_top - 1, 0)));
@@ -475,7 +480,7 @@ pub fn Renderer(PlaneWidth: f32, PlaneHeight: f32) type {
                                             texel_y += inv_nom_len;
                                         }) {
                                             const ty = @floatToInt(c_uint, std.math.modf(texel_y).fpart * constants.TextureDim);
-                                            const texel = walls_image.getPixel(.{ .x = t_lower_off + texstrip, .y = ty });
+                                            const texel = walls_image.getPixel(.{ .x = t_lower_off + texcol, .y = ty });
 
                                             pixels[pix_index] = texel;
                                             self.z_buffer[pix_index] = adj_distance;
@@ -483,28 +488,46 @@ pub fn Renderer(PlaneWidth: f32, PlaneHeight: f32) type {
                                         highest_drawn = constrained_top;
                                     }
                                 }
+                                previous_layer_height = layer.height;
+                            }
+
+                            // do we potentially draw horizontal surfaces?
+                            if (highest_drawn < PlaneHeight / 2) {
+                                // Note: next_top can never exceed PlaneHeight / 2 in
+                                // the body of the next block. If the wall is taller
+                                // than us the back edge is lower than the front one so
+                                // this check will fail as we just drew it (or higher
+                                // than it). If the wall is shorter then the back edge
+                                // is at most the horizon. Similarly so for next_bottom
+                                const next_top = PlaneHeight / 2 + PlaneDist * (layer.height - pheight) / next_distance;
+                                if (false and next_top > highest_drawn) {
+                                    const toff = cell.floor_texture * @floatToInt(c_uint, constants.TextureDim);
+
+                                    top_of_floor = std.math.ceil(std.math.min(std.math.min(next_top, lowest_drawn), PlaneHeight / 2 - 1));
+                                    const thresh = std.math.ceil(highest_drawn);
 
-                                // if (draw_upper) {
-                                //     const proj_default_end = PlaneHeight / 2 + PlaneDist * (level.Cell.DEFAULT_HEIGHT - pheight) / adj_distance;
-                                //     const constrained_top = std.math.min(lowest_drawn, proj_default_end);
-                                //     const constrained_bottom = std.math.ceil(std.math.max(bottom_of_ceiling, highest_drawn));
-                                //     const stop = @floatToInt(usize, PlaneWidth * (PlaneHeight - constrained_bottom)) + col;
-                                //     const t_upper_off = cell.upper_texture * td;
-                                //     const pix_y = @floatToInt(usize, std.math.ceil(std.math.max(PlaneHeight - constrained_top - 1, 0)));
-                                //     var pix_index = pix_y * @floatToInt(usize, PlaneWidth) + col;
-                                //     var texel_y: f32 = constants.TextureDim - (constrained_top - constrained_bottom) / nominal_length;
-                                //     while (pix_index < stop) : ({
-                                //         pix_index += @floatToInt(usize, PlaneWidth);
-                                //         texel_y += inv_nom_len;
-                                //     }) {
-                                //         const ty = @floatToInt(c_uint, std.math.modf(texel_y).fpart * constants.TextureDim);
-                                //         const texel = walls_image.getPixel(.{ .x = t_upper_off + texstrip, .y = ty });
+                                    const itop = @floatToInt(usize, std.math.max(top_of_floor, 0));
+                                    const ptop = @floatToInt(usize, PlaneHeight) - itop - 1;
+                                    var pix_index = ptop * @floatToInt(usize, PlaneWidth) + col;
+                                    while (top_of_floor > thresh) : ({
+                                        top_of_floor -= 1;
+                                        pix_index += @floatToInt(usize, PlaneWidth);
+                                    }) {
+                                        const row_dist = (pheight - cell.floor_height) * PlaneDist / (PlaneHeight / 2 - top_of_floor);
+                                        // draw the correct pixel
+                                        const sx = std.math.modf(ppos_x + row_dist * cosra).fpart;
+                                        const sy = std.math.modf(ppos_y + row_dist * sinra).fpart;
+                                        const px = @floatToInt(c_uint, constants.TextureDim * std.math.fabs(sx));
+                                        const py = @floatToInt(c_uint, constants.TextureDim * std.math.fabs(sy));
+                                        const val = surfaces_image.getPixel(.{ .x = toff + px, .y = py });
+                                        pixels[pix_index] = val;
 
-                                //         pixels[pix_index] = texel;
-                                //         self.z_buffer[pix_index] = adj_distance;
-                                //     }
-                                //     lowest_drawn = constrained_bottom;
-                                // }
+                                        // record in the z_buffer only if we're above the floor!
+                                        if (cell.floor_height > 0) self.z_buffer[pix_index] = row_dist;
+                                    }
+                                    // OVERDRAW
+                                    // highest_drawn = next_top;
+                                }
                             }
                         }
                     }
@@ -520,35 +543,6 @@ pub fn Renderer(PlaneWidth: f32, PlaneHeight: f32) type {
                     //     const next_top = PlaneHeight / 2 + PlaneDist * (cell.floor_height - pheight) / next_distance;
                     //     const next_bottom = PlaneHeight / 2 + PlaneDist * (cell.ceiling_height - pheight) / next_distance;
 
-                    //     // draw floor?
-                    //     if (false and next_top > highest_drawn) {
-                    //         const toff = cell.floor_texture * @floatToInt(c_uint, constants.TextureDim);
-
-                    //         top_of_floor = std.math.ceil(std.math.min(std.math.min(next_top, lowest_drawn), PlaneHeight / 2 - 1));
-                    //         const thresh = std.math.ceil(highest_drawn);
-
-                    //         const itop = @floatToInt(usize, std.math.max(top_of_floor, 0));
-                    //         const ptop = @floatToInt(usize, PlaneHeight) - itop - 1;
-                    //         var pix_index = ptop * @floatToInt(usize, PlaneWidth) + col;
-                    //         while (top_of_floor > thresh) : ({
-                    //             top_of_floor -= 1;
-                    //             pix_index += @floatToInt(usize, PlaneWidth);
-                    //         }) {
-                    //             const row_dist = (pheight - cell.floor_height) * PlaneDist / (PlaneHeight / 2 - top_of_floor);
-                    //             // draw the correct pixel
-                    //             const sx = std.math.modf(ppos_x + row_dist * cosra);
-                    //             const sy = std.math.modf(ppos_y + row_dist * sinra);
-                    //             const px = @floatToInt(c_uint, constants.TextureDim * std.math.fabs(sx.fpart));
-                    //             const py = @floatToInt(c_uint, constants.TextureDim * std.math.fabs(sy.fpart));
-                    //             const val = surfaces_image.getPixel(.{ .x = toff + px, .y = py });
-                    //             pixels[pix_index] = val;
-
-                    //             // record in the z_buffer only if we're above the floor!
-                    //             if (cell.floor_height > 0) self.z_buffer[pix_index] = row_dist;
-                    //         }
-                    //         highest_drawn = next_top;
-                    //     }
-
                     //     // draw ceiling?
                     //     if (false and cell.draw_down and next_bottom < lowest_drawn) {
                     //         const toff = cell.ceiling_texture * @floatToInt(c_uint, constants.TextureDim);