From 39259fc8ab2da78cf5de5ef59079657bbf01acff Mon Sep 17 00:00:00 2001
From: Mike Erwin <significant.bit@gmail.com>
Date: Mon, 8 Aug 2016 15:45:18 -0400
Subject: [PATCH] draw 3D cursor with new immediate mode

Replace legacy OpenGL with Gawain. Use shaders instead of fixed
function pipeline.

This simple UI element is shown at startup so is easy to verify things
are working. It also serves as a good example for people converting
other parts of the code.

Part of T49043
---
 .../editors/space_view3d/view3d_draw.c        | 55 +++++++++++++------
 1 file changed, 37 insertions(+), 18 deletions(-)

diff --git a/source/blender/editors/space_view3d/view3d_draw.c b/source/blender/editors/space_view3d/view3d_draw.c
index a166ef0877a..3903e4e1fe8 100644
--- a/source/blender/editors/space_view3d/view3d_draw.c
+++ b/source/blender/editors/space_view3d/view3d_draw.c
@@ -100,6 +100,8 @@
 #include "GPU_material.h"
 #include "GPU_compositing.h"
 #include "GPU_extensions.h"
+#include "GPU_shader.h"
+#include "GPU_immediate.h"
 
 #include "view3d_intern.h"  /* own include */
 
@@ -552,39 +554,56 @@ static void drawcursor(Scene *scene, ARegion *ar, View3D *v3d)
 		const float f20 = U.widget_unit;
 		
 		glLineWidth(1);
-		glShadeModel(GL_FLAT);
 
-		glBegin(GL_LINE_LOOP);
+		clear_VertexFormat(&immVertexFormat);
+		unsigned color = add_attrib(&immVertexFormat, "color", GL_UNSIGNED_BYTE, 3, NORMALIZE_INT_TO_FLOAT);
+		unsigned pos = add_attrib(&immVertexFormat, "pos", GL_FLOAT, 2, KEEP_FLOAT);
+		pack(&immVertexFormat);
+
+		immBindBuiltinProgram(GPU_SHADER_2D_FLAT_COLOR);
 
 		const int segments = 16;
+
+		immBegin(GL_LINE_LOOP, segments);
+
 		for (int i = 0; i < segments; ++i) {
 			float angle = 2 * M_PI * ((float)i / (float)segments);
 			float x = co[0] + f10 * cosf(angle);
 			float y = co[1] + f10 * sinf(angle);
 
 			if (i % 2 == 0)
-				glColor3ub(255,0,0);
+				immAttrib3ub(color, 255, 0, 0);
 			else
-				glColor3ub(255,255,255);
+				immAttrib3ub(color, 255, 255, 255);
 
-			glVertex2f(x,y);
+			immVertex2f(pos, x, y);
 		}
-		glEnd();
+		immEnd();
 
-		UI_ThemeColor(TH_VIEW_OVERLAY);
+		immUnbindProgram();
 
-		glBegin(GL_LINES);
-		glVertex2f(co[0] - f20, co[1]);
-		glVertex2f(co[0] - f5, co[1]);
-		glVertex2f(co[0] + f5, co[1]);
-		glVertex2f(co[0] + f20, co[1]);
-		glVertex2f(co[0], co[1] - f20);
-		glVertex2f(co[0], co[1] - f5);
-		glVertex2f(co[0], co[1] + f5);
-		glVertex2f(co[0], co[1] + f20);
-		glEnd();
+		clear_VertexFormat(&immVertexFormat);
+		pos = add_attrib(&immVertexFormat, "pos", GL_FLOAT, 2, KEEP_FLOAT);
+		pack(&immVertexFormat);
 
-		glShadeModel(GL_SMOOTH);
+		immBindBuiltinProgram(GPU_SHADER_2D_UNIFORM_COLOR);
+
+		float crosshair_color[3];
+		UI_GetThemeColor3fv(TH_VIEW_OVERLAY, crosshair_color);
+		immUniform4f("color", crosshair_color[0], crosshair_color[1], crosshair_color[2], 1.0f);
+
+		immBegin(GL_LINES, 8);
+		immVertex2f(pos, co[0] - f20, co[1]);
+		immVertex2f(pos, co[0] - f5, co[1]);
+		immVertex2f(pos, co[0] + f5, co[1]);
+		immVertex2f(pos, co[0] + f20, co[1]);
+		immVertex2f(pos, co[0], co[1] - f20);
+		immVertex2f(pos, co[0], co[1] - f5);
+		immVertex2f(pos, co[0], co[1] + f5);
+		immVertex2f(pos, co[0], co[1] + f20);
+		immEnd();
+
+		immUnbindProgram();
 	}
 }