UI: Perf: Batch icons drawcalls together.

For this we use a new shader that gets it's data from a uniform array.
Vertex shader position the vertices using these data.

Using glUniform is way faster than using imm for that matter.

Like BLF rendering, UI icons are always (as far as I know) non occluded and
displayed above everything else. They also does not overlap with texts so
they can be batched at the same time.

2 files changed, 59 insertions, 0 deletions

diff --git a/source/blender/gpu/shaders/gpu_shader_2D_image_multi_rect_vert.glsl b/source/blender/gpu/shaders/gpu_shader_2D_image_multi_rect_vert.glsl
new file mode 100644
index 00000000000..9fdf8ececc5
--- /dev/null
+++ b/source/blender/gpu/shaders/gpu_shader_2D_image_multi_rect_vert.glsl
@@ -0,0 +1,48 @@
+/**
+ * Simple shader that just draw multiple icons at the specified locations
+ * does not need any vertex input (producing less call to immBegin/End)
+ **/
+
+/* Same as ICON_DRAW_CACHE_SIZE */
+#define MAX_CALLS 16
+
+uniform vec4 calls_data[MAX_CALLS * 3];
+
+out vec2 texCoord_interp;
+flat out vec4 finalColor;
+
+void main()
+{
+	/* Rendering 2 triangle per icon. */
+	int i = gl_VertexID / 6;
+	int v = gl_VertexID % 6;
+
+	vec4 pos = calls_data[i*3];
+	vec4 tex = calls_data[i*3+1];
+	finalColor = calls_data[i*3+2];
+
+	/* TODO Remove this */
+	if (v == 2) v = 4;
+	else if (v == 3) v = 0;
+	else if (v == 5) v = 2;
+
+	if (v == 0) {
+		pos.xy = pos.xw;
+		tex.xy = tex.xw;
+	}
+	else if (v == 1) {
+		pos.xy = pos.xz;
+		tex.xy = tex.xz;
+	}
+	else if (v == 2) {
+		pos.xy = pos.yw;
+		tex.xy = tex.yw;
+	}
+	else {
+		pos.xy = pos.yz;
+		tex.xy = tex.yz;
+	}
+
+	gl_Position = vec4(pos.xy, 0.0f, 1.0f);
+	texCoord_interp = tex.xy;
+}
diff --git a/source/blender/gpu/shaders/gpu_shader_image_varying_color_frag.glsl b/source/blender/gpu/shaders/gpu_shader_image_varying_color_frag.glsl
new file mode 100644
index 00000000000..37686092700
--- /dev/null
+++ b/source/blender/gpu/shaders/gpu_shader_image_varying_color_frag.glsl
@@ -0,0 +1,11 @@
+
+in vec2 texCoord_interp;
+flat in vec4 finalColor;
+out vec4 fragColor;
+
+uniform sampler2D image;
+
+void main()
+{
+	fragColor = texture(image, texCoord_interp) * finalColor;
+}