partially done work on total source tree rework, separation of engine context and game context, generalization of renderer for different backends as well as web platform target

src/rendering/twn_rendering.c

@@ -0,0 +1,150 @@
+#include "twn_rendering_c.h"
+#include "townengine/twn_rendering.h"
+#include "townengine/textures/internal_api.h"
+#include "townengine/context.h"
+#include "townengine/camera.h"
+
+#include "twn_rendering_platform.h"
+
+#include <SDL2/SDL.h>
+#include <stb_ds.h>
+
+#ifdef EMSCRIPTEN
+#include <GLES2/gl2.h>
+#else
+#include <glad/glad.h>
+#endif
+
+#include <stddef.h>
+#include <tgmath.h>
+
+
+/* TODO: have a default initialized one */
+t_matrix4 camera_projection_matrix;
+t_matrix4 camera_look_at_matrix;
+
+
+void render_queue_clear(void) {
+    /* this doesn't even _deserve_ a TODO */
+    /* if you're gonna remove it, this is also being done in main.c */
+    for (size_t i = 0; i < arrlenu(ctx.render_queue_2d); ++i) {
+        if (ctx.render_queue_2d[i].type == PRIMITIVE_2D_TEXT) {
+            free(ctx.render_queue_2d[i].text.text);
+        }
+    }
+    
+    /* since i don't intend to free the queues, */
+    /* it's faster and simpler to just "start over" */
+    /* and start overwriting the existing data */
+    arrsetlen(ctx.render_queue_2d, 0);
+
+    for (size_t i = 0; i < hmlenu(ctx.uncolored_mesh_batches); ++i)
+        arrsetlen(ctx.uncolored_mesh_batches[i].value.primitives, 0);
+}
+
+
+/* rectangle */
+void push_rectangle(t_frect rect, t_color color) {
+    struct rect_primitive rectangle = {
+        .rect = rect,
+        .color = color,
+    };
+
+    struct primitive_2d primitive = {
+        .type = PRIMITIVE_2D_RECT,
+        .rect = rectangle,
+    };
+
+    arrput(ctx.render_queue_2d, primitive);
+}
+
+
+static void render_2d(void) {
+    use_2d_pipeline();
+
+    const size_t render_queue_len = arrlenu(ctx.render_queue_2d);
+
+    size_t batch_count = 0;
+
+    for (size_t i = 0; i < render_queue_len; ++i) {
+        const struct primitive_2d *current = &ctx.render_queue_2d[i];
+
+        switch (current->type) {
+            case PRIMITIVE_2D_SPRITE: {
+                const struct sprite_batch batch =
+                    collect_sprite_batch(current, render_queue_len - i);
+
+                /* TODO: what's even the point? just use OR_EQUAL comparison */
+                set_depth_range((double)batch_count / UINT16_MAX, 1.0);
+                render_sprites(current, batch);
+
+                i += batch.size - 1; ++batch_count;
+                break;
+            }
+            case PRIMITIVE_2D_RECT:
+                render_rectangle(&current->rect);
+                break;
+            case PRIMITIVE_2D_CIRCLE:
+                render_circle(&current->circle);
+                break;
+            case PRIMITIVE_2D_TEXT:
+                render_text(&current->text);
+                break;
+        }
+    }
+}
+
+
+static void render_space(void) {
+    /* nothing to do, abort */
+    /* as space pipeline isn't used we can have fewer changes and initialization costs */
+    if (hmlenu(ctx.uncolored_mesh_batches) == 0)
+        return;
+
+    use_space_pipeline();
+
+    for (size_t i = 0; i < hmlenu(ctx.uncolored_mesh_batches); ++i) {
+        draw_uncolored_space_traingle_batch(&ctx.uncolored_mesh_batches[i].value,
+                                            ctx.uncolored_mesh_batches[i].key);
+    }
+}
+
+
+void render(void) {
+    textures_update_atlas(&ctx.texture_cache);
+
+    /* fit rendering context onto the resizable screen */
+    if (ctx.window_size_has_changed) {
+        if ((float)ctx.window_w / (float)ctx.window_h > RENDER_BASE_RATIO) {
+            float ratio = (float)ctx.window_h / (float)RENDER_BASE_HEIGHT;
+            int w = (int)((float)RENDER_BASE_WIDTH * ratio);
+            setup_viewport(
+                ctx.window_w / 2 - w / 2,
+                0,
+                w,
+                ctx.window_h
+            );
+        } else {
+            float ratio = (float)ctx.window_w / (float)RENDER_BASE_WIDTH;
+            int h = (int)((float)RENDER_BASE_HEIGHT * ratio);
+            setup_viewport(
+                0,
+                ctx.window_h / 2 - h / 2,
+                ctx.window_w,
+                h
+            );
+        }
+    }
+
+    clear_draw_buffer();
+    render_space();
+    render_2d();
+    swap_buffers();
+}
+
+
+void set_camera(const t_camera *const camera) {
+    /* TODO: skip recaulculating if it's the same? */
+    camera_projection_matrix = camera_perspective(camera);
+    camera_look_at_matrix    = camera_look_at(camera);
+}