From 0d4ba9455ed5043a18bc0d157a0f1f04fd5476ea Mon Sep 17 00:00:00 2001
From: _ <_@_>
Date: Fri, 25 Dec 2020 11:41:26 -0600
Subject: [PATCH] update: finally drawing a heightmap

---
 src/bin/terrain.rs | 56 +++++++++++++++++++++++++++++++++++++---------
 1 file changed, 45 insertions(+), 11 deletions(-)

diff --git a/src/bin/terrain.rs b/src/bin/terrain.rs
index 97f996e..64e43ff 100644
--- a/src/bin/terrain.rs
+++ b/src/bin/terrain.rs
@@ -28,6 +28,10 @@ use opengl_rust::{
 	timestep::TimeStep,
 };
 
+struct GameState {
+	logic_frames: u64,
+}
+
 struct GraphicsContext {
 	window: sdl2::video::Window,
 	gl_ctx: sdl2::video::GLContext,
@@ -59,14 +63,18 @@ impl ShaderLocations {
 	}
 }
 
-#[instrument (level = "trace", skip (ctx))]
-fn draw_graphics (ctx: &GraphicsContext) {
+#[instrument (level = "trace", skip (ctx, state))]
+fn draw_graphics (ctx: &GraphicsContext, state: &GameState) 
+{
 	let shader_locs = &ctx.shader_locations;
 	let attr_pos = shader_locs.attr_pos;
 	let attr_color = shader_locs.attr_color;
 	let uni_mvp = shader_locs.uni_mvp;
 	
 	ctx.window.gl_make_current (&ctx.gl_ctx).unwrap ();
+	
+	glezz::enable (gl::DEPTH_TEST);
+	
 	glezz::clear_color (0.392f32, 0.710f32, 0.965f32, 1.0f32);
 	glezz::clear (gl::COLOR_BUFFER_BIT | gl::DEPTH_BUFFER_BIT | gl::STENCIL_BUFFER_BIT);
 	
@@ -74,8 +82,13 @@ fn draw_graphics (ctx: &GraphicsContext) {
 	
 	let proj_mat = Mat4::perspective_rh_gl (30.0f32.to_radians (), screen_size.0 / screen_size.1, 0.125, 200.0);
 	
+	let spin_period = 360 * 4;
+	
 	let view_mat = proj_mat *
-	Mat4::from_translation (Vec3::from ((0.0, 0.0, -20.0)));
+	Mat4::from_translation (Vec3::from ((0.0, 0.0, -80.0))) *
+	Mat4::from_rotation_x (-60.0 * 3.14159 / 180.0) *
+	Mat4::from_rotation_z ((state.logic_frames % spin_period) as f32 * 3.1415926535 * 2.0 / spin_period as f32) *
+	Mat4::from_translation (Vec3::from ((-32.0, -32.0, -5.0)));
 	
 	let mvp = view_mat;
 	
@@ -141,6 +154,15 @@ fn main () -> anyhow::Result <()> {
 	let mut indexes = vec![];
 	let mut start_index = 0;
 	
+	let height_fn = |x, y| {
+		let x = x - 32.0;
+		let y = y - 32.0;
+		
+		let d = x * x + y * y;
+		
+		f32::max (0.0, 5.0 - d * 0.125)
+	};
+	
 	for y in 0..64 {
 		for x in 0..64 {
 			let (r, g, b) = if (x + y) % 2 == 0 {
@@ -154,12 +176,20 @@ fn main () -> anyhow::Result <()> {
 			let y = y as f32;
 			let i = start_index;
 			
-			vertexes.extend (&[
-				x + 0.0, y + 0.0, 0.0, r, g, b,
-				x + 1.0, y + 0.0, 0.0, r, g, b,
-				x + 1.0, y + 1.0, 0.0, r, g, b,
-				x + 0.0, y + 1.0, 0.0, r, g, b,
-			]);
+			let xys = [
+				(x + 0.0, y + 0.0),
+				(x + 1.0, y + 0.0),
+				(x + 1.0, y + 1.0),
+				(x + 0.0, y + 1.0),
+			];
+			
+			for (x, y) in &xys {
+				vertexes.extend (&[
+					*x, *y, height_fn (*x, *y),
+					r, g, b,
+				])
+			}
+			
 			indexes.extend (&[
 				i + 0, i + 1, i + 2,
 				i + 0, i + 2, i + 3,
@@ -182,6 +212,10 @@ fn main () -> anyhow::Result <()> {
 		shader_locations,
 	};
 	
+	let mut game_state = GameState {
+		logic_frames: 0,
+	};
+	
 	'running: loop {
 		let frames_to_do = time_step.step ();
 		
@@ -198,10 +232,10 @@ fn main () -> anyhow::Result <()> {
 		}
 		
 		for _ in 0..frames_to_do {
-			
+			game_state.logic_frames += 1;
 		}
 		
-		draw_graphics (&graphics_ctx);
+		draw_graphics (&graphics_ctx, &game_state);
 		graphics_frames += 1;
 		
 		std::thread::sleep (Duration::from_millis (15));