update: add grid

shaders/terrain-frag.glsl

@@ -0,0 +1,9 @@
+#define lowp
+#define mediump
+#define highp
+#line 0
+varying lowp vec3 vary_color;
+
+void main (void) {
+	gl_FragColor = vec4 (vary_color, 1.0);
+}

shaders/terrain-vert.glsl

@@ -0,0 +1,15 @@
+#define lowp
+#define mediump
+#define highp
+#line 0
+attribute highp vec4 attr_pos;
+attribute lowp vec3 attr_color;
+
+uniform highp mat4 uni_mvp;
+
+varying lowp vec3 vary_color;
+
+void main (void) {
+	vary_color = attr_color;
+	gl_Position = uni_mvp * attr_pos;
+}

src/bin/terrain.rs

@@ -11,6 +11,10 @@ use anyhow::{
 	anyhow,
 	Context,
 };
+use glam::{
+	Mat4,
+	Vec3,
+};
 use sdl2::{
 	event::Event,
 	keyboard::{Keycode, Scancode},
@@ -31,26 +35,64 @@ struct GraphicsContext {
 	index_buffer: gpu_buffers::IndexBuffer,
 	
 	shader_program: shader::ShaderProgram,
+	shader_locations: ShaderLocations,
+}
+
+struct ShaderLocations {
 	attr_pos: u32,
+	attr_color: u32,
+	uni_mvp: i32,
+}
+
+impl ShaderLocations {
+	pub fn new (shader_program: &shader::ShaderProgram) -> anyhow::Result <Self> 
+	{
+		let attr = |name: &str| shader_program.get_attribute_location (&CString::new (name.as_bytes ())?).try_into ().context ("Attribute location negative");
+		let uni = |name: &str| shader_program.get_uniform_location (&CString::new (name.as_bytes ())?).try_into ().context ("Uniform location bad");
+		
+		Ok (Self {
+			attr_pos:   attr ("attr_pos")?,
+			attr_color: attr ("attr_color")?,
+			uni_mvp:    uni ("uni_mvp")?,
+		})
+	}
 }
 
 fn draw_graphics (ctx: &GraphicsContext) {
-	let attr_pos = ctx.attr_pos;
+	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::clear_color (0.392f32, 0.710f32, 0.965f32, 1.0f32);
 	glezz::clear (gl::COLOR_BUFFER_BIT | gl::DEPTH_BUFFER_BIT | gl::STENCIL_BUFFER_BIT);
 	
+	let screen_size = (960.0, 540.0);
+	
+	let proj_mat = Mat4::perspective_rh_gl (30.0f32.to_radians (), screen_size.0 / screen_size.1, 0.125, 200.0);
+	
+	let view_mat = proj_mat *
+	Mat4::from_translation (Vec3::from ((0.0, 0.0, -20.0)));
+	
+	let mvp = view_mat;
+	
+	glezz::uniform_matrix_4fv (uni_mvp, &mvp);
+	
 	ctx.shader_program.use_program ();
 	glezz::enable_vertex_attrib_array (Some (attr_pos));
+	glezz::enable_vertex_attrib_array (Some (attr_color));
 	
 	ctx.vertex_buffer.bind ();
 	ctx.index_buffer.bind ();
 	
 	unsafe {
-		gl::VertexAttribPointer (attr_pos, 2, gl::FLOAT, 0, 4 * 2, 0 as *const u8 as *const c_void);
+		let num_quads = 4 * 4;
+		let stride = 4 * 6;
+		gl::VertexAttribPointer (attr_pos, 3, gl::FLOAT, 0, stride, 0 as *const u8 as *const c_void);
+		gl::VertexAttribPointer (attr_color, 3, gl::FLOAT, 0, stride, (4 * 3) as *const u8 as *const c_void);
 		
-		gl::DrawRangeElements (gl::TRIANGLES, 0, 6, 6, gl::UNSIGNED_INT, 0 as *const u8 as *const c_void);
+		gl::DrawRangeElements (gl::TRIANGLES, 0, num_quads * 4, num_quads as i32 * 6, gl::UNSIGNED_INT, 0 as *const u8 as *const c_void);
 	}
 	
 	ctx.window.gl_swap_window ();
@@ -85,43 +127,42 @@ fn main () -> anyhow::Result <()> {
 	
 	let mut event_pump = sdl_context.event_pump ().unwrap ();
 	
-	let vertex_shader = shader::ShaderObject::from_source (gl::VERTEX_SHADER, b"
-#define lowp
-#define mediump
-#define highp
-#line 0
-attribute highp vec4 attr_pos;
+	let shader_program = shader::shader_from_files ("shaders/terrain-vert.glsl", "shaders/terrain-frag.glsl");
+	let shader_locations = ShaderLocations::new (&shader_program)?;
 	
-void main (void) {
-	gl_Position = attr_pos;
-}
-	").map_err (|e| anyhow! ("Can't create vertex shader: {}", e))?;
+	let mut vertexes = vec![];
+	let mut indexes = vec![];
+	let mut start_index = 0;
 	
-	let fragment_shader = shader::ShaderObject::from_source (gl::FRAGMENT_SHADER, b"
-#define lowp
-#define mediump
-#define highp
-#line 0
-void main (void) {
-	gl_FragColor = vec4 (0.329, 0.431, 0.478, 1.0);
-}
-	").map_err (|e| anyhow! ("Can't create fragment shader: {}", e))?;
+	for y in 0..4 {
+		for x in 0..4 {
+			let (r, g, b) = if (x + y) % 2 == 0 {
+				(0.4, 0.4, 0.4)
+			}
+			else {
+				(0.6, 0.6, 0.6)
+			};
 			
-	let shader_program = shader::ShaderProgram::new (&vertex_shader, &fragment_shader).map_err (|e| anyhow! ("Can't link shader program: {}", e))?;
+			let x = x as f32;
+			let y = y as f32;
+			let i = start_index;
 			
-	let attr_pos = shader_program.get_attribute_location (&CString::new ("attr_pos".as_bytes ())?).try_into ()?;
+			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,
+			]);
+			indexes.extend (&[
+				i + 0, i + 1, i + 2,
+				i + 0, i + 2, i + 3,
+			]);
+			start_index += 4;
+		}
+	}
 	
-	let vertex_buffer = gpu_buffers::VertexBuffer::from_slice (&[
-		0.0, 0.0,
-		1.0, 0.0,
-		1.0, 1.0,
-		0.0, 1.0,
-	]);
-	
-	let index_buffer = gpu_buffers::IndexBuffer::from_slice_u32 (&[
-		0, 1, 2,
-		0, 2, 3
-	]);
+	let vertex_buffer = gpu_buffers::VertexBuffer::from_slice (&vertexes);
+	let index_buffer = gpu_buffers::IndexBuffer::from_slice_u32 (&indexes);
 	
 	let graphics_ctx = GraphicsContext {
 		window,
@@ -131,7 +172,7 @@ void main (void) {
 		index_buffer,
 		
 		shader_program,
-		attr_pos,
+		shader_locations,
 	};
 	
 	'running: loop {