From c49789f1f42c707827dd98ac8f539b4d0467f1f3 Mon Sep 17 00:00:00 2001
From: veclavtalica <veclavtalica@poto.cafe>
Date: Sat, 19 Oct 2024 20:02:39 +0300
Subject: [PATCH] make deferred space triangles work

---
 src/rendering/twn_gl_15_rendering.c | 79 ++++++++++++++++-------------
 1 file changed, 43 insertions(+), 36 deletions(-)

diff --git a/src/rendering/twn_gl_15_rendering.c b/src/rendering/twn_gl_15_rendering.c
index b548772..187e971 100644
--- a/src/rendering/twn_gl_15_rendering.c
+++ b/src/rendering/twn_gl_15_rendering.c
@@ -104,6 +104,9 @@ typedef struct {
     GLsizei element_count;
     GLsizei range_start, range_end;
 
+    /* could be either `element_count` with supplied `element_buffer`, or this, but not both */
+    GLsizei primitive_count;
+
     double depth_range_low, depth_range_high;
 } DeferredCommandDraw;
 
@@ -228,8 +231,7 @@ static void issue_deferred_draw_commands(void) {
                 /* TODO: don't assume a single vertex array ? */
                 SDL_assert(command.vertices.arity != 0);
                 SDL_assert(command.vertices.buffer);
-                SDL_assert(command.element_count != 0);
-                SDL_assert(command.element_buffer);
+                SDL_assert((command.element_buffer && command.element_count != 0) || command.primitive_count != 0);
 
                 glBindBuffer(GL_ARRAY_BUFFER, command.vertices.buffer);
                 glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, command.element_buffer);
@@ -274,15 +276,21 @@ static void issue_deferred_draw_commands(void) {
                         textures_bind(&ctx.texture_cache, command.texture_key);
                 }
 
-                if (command.range_start == command.range_end)
-                    glDrawElements(GL_TRIANGLES, command.element_count, GL_UNSIGNED_SHORT, NULL);
-                else
-                    glDrawRangeElements(GL_TRIANGLES,
-                                        command.range_start,
-                                        command.range_end,
-                                        command.element_count,
-                                        GL_UNSIGNED_SHORT,
-                                        NULL);
+                if (command.element_buffer) {
+                    SDL_assert(command.element_count != 0);
+                    if (command.range_start == command.range_end)
+                        glDrawElements(GL_TRIANGLES, command.element_count, GL_UNSIGNED_SHORT, NULL);
+                    else
+                        glDrawRangeElements(GL_TRIANGLES,
+                                            command.range_start,
+                                            command.range_end,
+                                            command.element_count,
+                                            GL_UNSIGNED_SHORT,
+                                            NULL);
+                } else {
+                    SDL_assert(command.primitive_count != 0);
+                    glDrawArrays(GL_TRIANGLES, 0, command.primitive_count);
+                }
 
                 /* state clearing */
 
@@ -735,37 +743,36 @@ void finally_draw_uncolored_space_traingle_batch(const MeshBatch *batch,
                                                  const TextureKey texture_key,
                                                  const VertexBuffer buffer)
 {
-    const size_t primitives_len = arrlenu(batch->primitives);
+    DeferredCommandDraw command = {0};
 
-    textures_bind(&ctx.texture_cache, texture_key);
+    command.vertices = (AttributeArrayPointer) {
+        .arity = 3,
+        .type = GL_FLOAT,
+        .stride = offsetof(struct UncoloredSpaceTrianglePayload, v1),
+        .offset = offsetof(struct UncoloredSpaceTrianglePayload, v0),
+        .buffer = buffer
+    };
 
-    use_texture_mode(textures_get_mode(&ctx.texture_cache, texture_key));
+    command.texcoords = (AttributeArrayPointer) {
+        .arity = 2,
+        .type = GL_FLOAT,
+        .stride = offsetof(struct UncoloredSpaceTrianglePayload, v1),
+        .offset = offsetof(struct UncoloredSpaceTrianglePayload, uv0),
+        .buffer = buffer
+    };
 
-    glBindBuffer(GL_ARRAY_BUFFER, buffer);
+    command.textured = true;
+    command.texture_key = texture_key;
 
-    /* vertex specification*/
-    glEnableClientState(GL_VERTEX_ARRAY);
-    glVertexPointer(3,
-                    GL_FLOAT,
-                    offsetof(struct UncoloredSpaceTrianglePayload, v1),
-                    (void *)offsetof(struct UncoloredSpaceTrianglePayload, v0));
+    const GLuint primitives_len = arrlenu(batch->primitives);
+    command.primitive_count = 3 * primitives_len;
 
-    glEnableClientState(GL_TEXTURE_COORD_ARRAY);
-    glClientActiveTexture(GL_TEXTURE0);
-    glTexCoordPointer(2,
-                      GL_FLOAT,
-                      offsetof(struct UncoloredSpaceTrianglePayload, v1),
-                      (void *)offsetof(struct UncoloredSpaceTrianglePayload, uv0));
+    DeferredCommand final_command = {
+        .type = DEFERRED_COMMAND_TYPE_DRAW,
+        .draw = command
+    };
 
-    /* commit for drawing */
-    glDrawArrays(GL_TRIANGLES, 0, 3 * (GLint)primitives_len);
-
-    glDisableClientState(GL_TEXTURE_COORD_ARRAY);
-    glDisableClientState(GL_VERTEX_ARRAY);
-
-    /* invalidate the buffer immediately */
-    glBufferData(GL_ARRAY_BUFFER, 0, NULL, GL_STREAM_DRAW);
-    glBindBuffer(GL_ARRAY_BUFFER, 0);
+    arrpush(deferred_commands, final_command);
 }