From c498727471a140f39d83c63b40ff638db7ccc50f Mon Sep 17 00:00:00 2001
From: Sylvain Becker <[EMAIL REDACTED]>
Date: Fri, 7 Jan 2022 22:14:28 +0100
Subject: [PATCH] render: Use RenderGeometry to draw lines
This patch is from @1bsyl
Fixes #5061.
---
src/render/SDL_render.c | 123 +++++++++++++++++++++++++++++++++++++++-
1 file changed, 121 insertions(+), 2 deletions(-)
diff --git a/src/render/SDL_render.c b/src/render/SDL_render.c
index 787f69e9209..d4668f69954 100644
--- a/src/render/SDL_render.c
+++ b/src/render/SDL_render.c
@@ -2962,7 +2962,7 @@ int
SDL_RenderDrawLinesF(SDL_Renderer * renderer,
const SDL_FPoint * points, int count)
{
- int retval;
+ int retval = 0;
CHECK_RENDERER_MAGIC(renderer, -1);
@@ -2984,7 +2984,126 @@ SDL_RenderDrawLinesF(SDL_Renderer * renderer,
return RenderDrawLinesWithRectsF(renderer, points, count);
}
- retval = QueueCmdDrawLines(renderer, points, count);
+ if (!(renderer->info.flags & SDL_RENDERER_SOFTWARE) && renderer->QueueGeometry) {
+ SDL_bool isstack1;
+ SDL_bool isstack2;
+ float *xy = SDL_small_alloc(float, 4 * 2 * count, &isstack1);
+ int *indices = SDL_small_alloc(int,
+ (4) * 3 * (count - 1)
+ + (2) * 3 * (count)
+ , &isstack2);
+
+ if (xy && indices) {
+ int i;
+ float *ptr_xy = xy;
+ int *ptr_indices = indices;
+ const int xy_stride = 2 * sizeof (float);
+ int num_vertices = 4 * count;
+ int num_indices = 0;
+ const int size_indices = 4;
+ int cur_indice = -4;
+ const int is_looping = (points[0].x == points[count - 1].x && points[0].y == points[count - 1].y);
+ SDL_FPoint p; /* previous point */
+ p.x = p.y = 0.0f;
+ /* p q
+
+ 0----1------ 4----5
+ | \ |``\ | \ |
+ | \ | ` `\| \ |
+ 3----2-------7----6
+ */
+ for (i = 0; i < count; ++i) {
+ SDL_FPoint q = points[i]; /* current point */
+
+ *ptr_xy++ = q.x;
+ *ptr_xy++ = q.y;
+ *ptr_xy++ = q.x + 1.0f;
+ *ptr_xy++ = q.y;
+ *ptr_xy++ = q.x + 1.0f;
+ *ptr_xy++ = q.y + 1.0f;
+ *ptr_xy++ = q.x;
+ *ptr_xy++ = q.y + 1.0f;
+
+#define ADD_TRIANGLE(i1, i2, i3) \
+ *ptr_indices++ = cur_indice + i1; \
+ *ptr_indices++ = cur_indice + i2; \
+ *ptr_indices++ = cur_indice + i3; \
+ num_indices += 3; \
+
+ /* closed polyline, donĀ“t draw twice the point */
+ if (i || is_looping == 0) {
+ ADD_TRIANGLE(4, 5, 6)
+ ADD_TRIANGLE(4, 6, 7)
+ }
+
+ /* first point only, no segment */
+ if (i == 0) {
+ p = q;
+ cur_indice += 4;
+ continue;
+ }
+
+ /* draw segment */
+ if (p.y == q.y) {
+ if (p.x < q.x) {
+ ADD_TRIANGLE(1, 4, 7)
+ ADD_TRIANGLE(1, 7, 2)
+ } else {
+ ADD_TRIANGLE(5, 0, 3)
+ ADD_TRIANGLE(5, 3, 6)
+ }
+ } else if (p.x == q.x) {
+ if (p.y < q.y) {
+ ADD_TRIANGLE(2, 5, 4)
+ ADD_TRIANGLE(2, 4, 3)
+ } else {
+ ADD_TRIANGLE(6, 1, 0)
+ ADD_TRIANGLE(6, 0, 7)
+ }
+ } else {
+ if (p.y < q.y) {
+ if (p.x < q.x) {
+ ADD_TRIANGLE(1, 5, 4)
+ ADD_TRIANGLE(1, 4, 2)
+ ADD_TRIANGLE(2, 4, 7)
+ ADD_TRIANGLE(2, 7, 3)
+ } else {
+ ADD_TRIANGLE(4, 0, 5)
+ ADD_TRIANGLE(5, 0, 3)
+ ADD_TRIANGLE(5, 3, 6)
+ ADD_TRIANGLE(6, 3, 2)
+ }
+ } else {
+ if (p.x < q.x) {
+ ADD_TRIANGLE(0, 4, 7)
+ ADD_TRIANGLE(0, 7, 1)
+ ADD_TRIANGLE(1, 7, 6)
+ ADD_TRIANGLE(1, 6, 2)
+ } else {
+ ADD_TRIANGLE(6, 5, 1)
+ ADD_TRIANGLE(6, 1, 0)
+ ADD_TRIANGLE(7, 6, 0)
+ ADD_TRIANGLE(7, 0, 3)
+ }
+ }
+ }
+
+ p = q;
+ cur_indice += 4;
+ }
+
+ retval = QueueCmdGeometry(renderer, NULL,
+ xy, xy_stride, &renderer->color, 0 /* color_stride */, NULL, 0,
+ num_vertices, indices, num_indices, size_indices,
+ 1.0f, 1.0f);
+
+ SDL_small_free(xy, isstack1);
+ SDL_small_free(indices, isstack2);
+ }
+
+ } else {
+ retval = QueueCmdDrawLines(renderer, points, count);
+ }
return retval < 0 ? retval : FlushRenderCommandsIfNotBatching(renderer);
}