Memory buffer fixes

1 files changed, 31 insertions, 11 deletions

diff --git a/graphics.c b/graphics.c
index 95cff6b..670610b 100755
--- a/graphics.c
+++ b/graphics.c
@@ -248,6 +248,10 @@ enum {
   CHAR_NUM_BITS_   = CHAR_NUM_BITS_X_ * CHAR_NUM_BITS_Y_,
 };
 
+static i64 min2_i64_(i64 x, i64 y) {
+  return x < y ? x : y;
+}
+
 static f32 max2_f32_(f32 a, f32 b) {
   return a < b ? b : a;
 }
@@ -344,11 +348,25 @@ void draw_pixels_to_buffer(Pixel_Buffer dst, Box area, Pixel_Buffer src) {
   for (i64 j = j0; j < j1; ++j) {
     i64 src_j = (i64) floor(((j - area.y + .5) * src.height) * h_inv);
     if (src_j < 0 || src_j >= src.height) continue;
-    i64 src_n = src_j * src.stride;
+    vec4_f32 *q = src.pixels + src_j * src.stride;
+    vec4_f32 *p = dst.pixels + j     * dst.stride + i0;
     for (i64 i = i0; i < i1; ++i) {
       i64 src_i = (i64) floor(((i - area.x + .5) * src.width) * w_inv);
       if (src_i < 0 || src_i >= src.width) continue;
-      put_pixel_(dst, src.pixels[src_n + src_i], i, j);
+      vec4_f32 color = q[src_i];
+      if (color.w == 1.f)
+        *p = color;
+      else {
+        vec4_f32 dst_color  = *p;
+        f32      dst_amount = 1. - color.w;
+        *p = (vec4_f32) {
+          .x = dst_color.x * dst_amount + color.x * color.w,
+          .y = dst_color.y * dst_amount + color.y * color.w,
+          .z = dst_color.z * dst_amount + color.z * color.w,
+          .w = max2_f32_(dst_color.w, color.w),
+        };
+      }
+      ++p;
     }
   }
 }
@@ -1948,8 +1966,10 @@ static void scale_and_perform_graphics_request_(Graphics_Context context, Graphi
 
 static Graphics_Context graphics_context_defaults_(Graphics_Context context) {
   if (context.dst.pixels == NULL) {
+    i64 max_height = g_platform.num_pixels / g_platform.frame_width;
+
     context.dst.width  = g_platform.frame_width;
-    context.dst.height = g_platform.frame_height;
+    context.dst.height = min2_i64_(max_height, g_platform.frame_height);
     context.dst.stride = g_platform.frame_width;
     context.dst.pixels = g_platform.pixels;
 
@@ -2076,19 +2096,19 @@ TEST("colors") {
   REQUIRE_EQ((purple.z + 2e-7) * 100, 100);
 }
 
-Pixel_Buffer pixels = {
+static Pixel_Buffer _test_pixels = {
   .width  = 1280,
   .height = 720,
   .stride = 1280,
   .pixels = (vec4_f32[1280 * 720]) {0},
 };
 
-vec4_f32 color = { 1., 1., 1., 1., };
+static vec4_f32 _test_color = { 1., 1., 1., 1., };
 
 BENCHMARK("fill rectangle") {
   BENCHMARK_BEGIN;
   {
-    fill_rectangle_to_buffer(pixels, color, (Box) { .x = 100, .y = 100, .width = 300, .height = 200, });
+    fill_rectangle_to_buffer(_test_pixels, _test_color, (Box) { .x = 100, .y = 100, .width = 300, .height = 200, });
   }
   BENCHMARK_END;
 }
@@ -2096,7 +2116,7 @@ BENCHMARK("fill rectangle") {
 BENCHMARK("fill triangle") {
   BENCHMARK_BEGIN;
   {
-    fill_triangle_to_buffer(pixels, color, (vec2[3]) {
+    fill_triangle_to_buffer(_test_pixels, _test_color, (vec2[3]) {
       { 100, 100 },
       { 300, 100 },
       { 200, 250 },
@@ -2108,7 +2128,7 @@ BENCHMARK("fill triangle") {
 BENCHMARK("fill quad") {
   BENCHMARK_BEGIN;
   {
-    fill_quad_to_buffer(pixels, color, (vec2[4]) {
+    fill_quad_to_buffer(_test_pixels, _test_color, (vec2[4]) {
       { 100, 100 },
       { 300, 100 },
       { 300, 200 },
@@ -2121,7 +2141,7 @@ BENCHMARK("fill quad") {
 BENCHMARK("fill ellipse") {
   BENCHMARK_BEGIN;
   {
-    fill_ellipse_to_buffer(pixels, color, (Box) { .x = 80, .y = 80, .width = 340, .height = 240, });
+    fill_ellipse_to_buffer(_test_pixels, _test_color, (Box) { .x = 80, .y = 80, .width = 340, .height = 240, });
   }
   BENCHMARK_END;
 }
@@ -2129,7 +2149,7 @@ BENCHMARK("fill ellipse") {
 BENCHMARK("fill line") {
   BENCHMARK_BEGIN;
   {
-    fill_line_to_buffer(pixels, color, (vec2[2]) {
+    fill_line_to_buffer(_test_pixels, _test_color, (vec2[2]) {
       { 100, 100 },
       { 300, 200 },
     }, 40);
@@ -2141,7 +2161,7 @@ BENCHMARK("draw text area") {
   BENCHMARK_BEGIN;
   {
     c32 text[] = { 'H', 'e', 'l', 'l', 'o', ',', ' ', 'S', 'a', 'i', 'l', 'o', 'r', '!', };
-    draw_text_area_to_buffer(pixels, color, (Box) { .x = 100, .y = 100, .width = 300, .height = 200, }, (vec2) { 100, 200 }, sizeof text / sizeof *text, text);
+    draw_text_area_to_buffer(_test_pixels, _test_color, (Box) { .x = 100, .y = 100, .width = 300, .height = 200, }, (vec2) { 100, 200 }, sizeof text / sizeof *text, text);
   }
   BENCHMARK_END;
 }