From 607ee777036bff11d1b318f8cfa6fbc4d4d2298a Mon Sep 17 00:00:00 2001
From: nefrace <nefrace@gmail.com>
Date: Fri, 9 May 2025 22:12:20 +0300
Subject: [PATCH] Indexed rendering

---
 src/main.odin | 37 +++++++++++++++++++++++++++++--------
 1 file changed, 29 insertions(+), 8 deletions(-)

diff --git a/src/main.odin b/src/main.odin
index 0868982..0e4b845 100644
--- a/src/main.odin
+++ b/src/main.odin
@@ -33,11 +33,14 @@ main :: proc() {
 		{{-0.5, 0, 0}, {1, 0, 0}},
 		{{0, 1.0, 0}, {0, 1, 0}},
 		{{0.5, 0, 0}, {0, 0, 1}},
-		{{0.5, 0, 0}, {1, 1, 0}},
 		{{0, -0.5, 0}, {0, 1, 1}},
-		{{-0.5, -0, 0}, {1, 0, 1}},
 	}
 	vertices_byte_size := len(vertices) * size_of(vertices[0])
+
+	indices := []u16{0, 1, 2, 0, 2, 3}
+	indices_byte_size := len(indices) * size_of(indices[0])
+
+
 	vertex_attrs := []sdl.GPUVertexAttribute {
 		{location = 0, format = .FLOAT3, offset = 0}, // Position
 		{location = 1, format = .FLOAT3, offset = size_of(Vec3)}, // Color
@@ -46,14 +49,21 @@ main :: proc() {
 		gpu,
 		sdl.GPUBufferCreateInfo{usage = {.VERTEX}, size = u32(vertices_byte_size)},
 	)
+	index_buf := sdl.CreateGPUBuffer(
+		gpu,
+		sdl.GPUBufferCreateInfo{usage = {.INDEX}, size = u32(indices_byte_size)},
+	)
 
 	transfer_buf := sdl.CreateGPUTransferBuffer(
 		gpu,
-		sdl.GPUTransferBufferCreateInfo{usage = .UPLOAD, size = u32(vertices_byte_size)},
+		sdl.GPUTransferBufferCreateInfo {
+			usage = .UPLOAD,
+			size = u32(vertices_byte_size + indices_byte_size),
+		},
 	)
 	{ 	// Copy verticies to the transfer buffer
 
-		transfer_mem := sdl.MapGPUTransferBuffer(
+		transfer_mem := transmute([^]byte)sdl.MapGPUTransferBuffer(
 			gpu,
 			transfer_buf,
 			false,
@@ -61,6 +71,7 @@ main :: proc() {
 		defer sdl.UnmapGPUTransferBuffer(gpu, transfer_buf)
 
 		mem.copy(transfer_mem, raw_data(vertices), vertices_byte_size)
+		mem.copy(transfer_mem[vertices_byte_size:], raw_data(indices), indices_byte_size)
 	}
 
 	{ 	// Upload buffer to gpu
@@ -75,6 +86,12 @@ main :: proc() {
 			{buffer = vertex_buf, size = u32(vertices_byte_size)},
 			false,
 		)
+		sdl.UploadToGPUBuffer(
+			copy_pass,
+			{transfer_buffer = transfer_buf, offset = u32(vertices_byte_size)},
+			{buffer = index_buf, size = u32(indices_byte_size)},
+			false,
+		)
 	}
 	sdl.ReleaseGPUTransferBuffer(gpu, transfer_buf)
 
@@ -136,9 +153,6 @@ main :: proc() {
 				if ev.key.scancode == .ESCAPE do break loop
 			}
 		}
-		cmd_buf := sdl.AcquireGPUCommandBuffer(gpu)
-		swaptex: ^sdl.GPUTexture
-		ok = sdl.WaitAndAcquireGPUSwapchainTexture(cmd_buf, window, &swaptex, nil, nil);assert(ok)
 
 		rotation += 1 * delta
 
@@ -147,6 +161,11 @@ main :: proc() {
 			linalg.matrix4_rotate_f32(rotation, {0, 1, 0})
 		ubo := UBO{proj * model_mat}
 
+
+		cmd_buf := sdl.AcquireGPUCommandBuffer(gpu)
+		swaptex: ^sdl.GPUTexture
+		ok = sdl.WaitAndAcquireGPUSwapchainTexture(cmd_buf, window, &swaptex, nil, nil);assert(ok)
+
 		if swaptex != nil {
 			color_target := sdl.GPUColorTargetInfo {
 				texture     = swaptex,
@@ -163,8 +182,10 @@ main :: proc() {
 				&(sdl.GPUBufferBinding{buffer = vertex_buf}),
 				1,
 			)
+			sdl.BindGPUIndexBuffer(render_pass, {buffer = index_buf}, ._16BIT)
 			sdl.PushGPUVertexUniformData(cmd_buf, 0, &ubo, size_of(ubo))
-			sdl.DrawGPUPrimitives(render_pass, u32(len(vertices)), 1, 0, 0)
+			// sdl.DrawGPUPrimitives(render_pass, u32(len(vertices)), 1, 0, 0)
+			sdl.DrawGPUIndexedPrimitives(render_pass, 6, 1, 0, 0, 0)
 			sdl.EndGPURenderPass(render_pass)
 
 		}