gui: draw image surfaces as GPU quads via glsl shaders

2 files changed, 43 insertions, 0 deletions

diff --git a/shaders/image.frag.glsl b/shaders/image.frag.glsl
new file mode 100644
index 00000000..927d5f65
--- /dev/null
+++ b/shaders/image.frag.glsl
@@ -0,0 +1,10 @@
+#version 450
+
+layout(set = 2, binding = 0) uniform sampler2D u_image;
+
+layout(location = 0) in vec2 v_uv;
+layout(location = 0) out vec4 o_col;
+
+void main() {
+    o_col = texture(u_image, v_uv);
+}
diff --git a/shaders/image.vert.glsl b/shaders/image.vert.glsl
new file mode 100644
index 00000000..ace55a53
--- /dev/null
+++ b/shaders/image.vert.glsl
@@ -0,0 +1,33 @@
+#version 450
+
+// One instance per Surface image attachment. The CPU has already converted
+// the pane's cell rectangle and the aspect-preserving contain fit to NDC.
+layout(location = 0) in vec4 a_rect;    // x0, y0, x1, y1
+layout(location = 1) in vec4 a_uv_rect; // u0, v0, u1, v1
+
+layout(location = 0) out vec2 v_uv;
+
+void main() {
+    vec2 pos;
+    int corner = gl_VertexIndex % 6;
+    if (corner == 0) {
+        pos = vec2(a_rect.x, a_rect.y);
+        v_uv = vec2(a_uv_rect.x, a_uv_rect.y);
+    } else if (corner == 1) {
+        pos = vec2(a_rect.z, a_rect.y);
+        v_uv = vec2(a_uv_rect.z, a_uv_rect.y);
+    } else if (corner == 2) {
+        pos = vec2(a_rect.z, a_rect.w);
+        v_uv = vec2(a_uv_rect.z, a_uv_rect.w);
+    } else if (corner == 3) {
+        pos = vec2(a_rect.x, a_rect.y);
+        v_uv = vec2(a_uv_rect.x, a_uv_rect.y);
+    } else if (corner == 4) {
+        pos = vec2(a_rect.z, a_rect.w);
+        v_uv = vec2(a_uv_rect.z, a_uv_rect.w);
+    } else {
+        pos = vec2(a_rect.x, a_rect.w);
+        v_uv = vec2(a_uv_rect.x, a_uv_rect.w);
+    }
+    gl_Position = vec4(pos, 0.0, 1.0);
+}