1 files changed, 192 insertions, 0 deletions

diff --git a/src/render/imm.c b/src/render/imm.c
new file mode 100644
index 0000000..8a93488
--- /dev/null
+++ b/src/render/imm.c
@@ -0,0 +1,192 @@
+#include "imm_impl.h"
+
+#include <gfx/core.h>
+#include <gfx/render/imm.h>
+#include <gfx/render/llr.h>
+#include <gfx/util/shader.h>
+
+#include <math/aabb3.h>
+
+#include <assert.h>
+#include <string.h> // memcpy
+
+bool gfx_imm_make(Imm* renderer, GfxCore* gfxcore, LLR* llr) {
+  assert(renderer);
+  assert(gfxcore);
+  assert(llr);
+
+  const size_t num_triangle_verts = GFX_IMM_MAX_NUM_TRIANGLES * 3;
+
+  renderer->gfxcore = gfxcore;
+  renderer->llr     = llr;
+
+  renderer->triangles = gfx_make_geometry(
+      gfxcore,
+      &(GeometryDesc){.type         = Triangles,
+                      .buffer_usage = BufferDynamic,
+                      .num_verts    = num_triangle_verts,
+                      .positions3d  = (BufferView3d){
+                           .size_bytes = num_triangle_verts * sizeof(vec3)}});
+  if (!renderer->triangles) {
+    goto cleanup;
+  }
+
+  renderer->shader = gfx_make_immediate_mode_shader(gfxcore);
+  if (!renderer->shader) {
+    goto cleanup;
+  }
+
+  gfx_imm_set_colour(renderer, vec4_make(0.0f, 0.0f, 0.0f, 1.0f));
+
+  return true;
+
+cleanup:
+  gfx_imm_destroy(renderer);
+  return false;
+}
+
+void gfx_imm_destroy(Imm* renderer) {
+  assert(renderer);
+  assert(renderer->gfxcore);
+
+  if (renderer->triangles) {
+    gfx_destroy_geometry(renderer->gfxcore, &renderer->triangles);
+    // TODO: Could also destroy the geometry's buffers here.
+  }
+
+  if (renderer->shader) {
+    gfx_destroy_shader_program(renderer->gfxcore, &renderer->shader);
+  }
+}
+
+void gfx_imm_flush(Imm* renderer) {
+  assert(renderer);
+
+  if (renderer->num_triangle_verts > 0) {
+    gfx_update_geometry(
+        renderer->triangles,
+        &(GeometryDesc){
+            .num_verts   = renderer->num_triangle_verts,
+            .positions3d = (BufferView3d){
+                                          .data       = renderer->triangle_verts,
+                                          .size_bytes = renderer->num_triangle_verts * sizeof(vec3)}
+    });
+
+    gfx_llr_render_geometry(renderer->llr, renderer->triangles);
+
+    renderer->num_triangle_verts = 0;
+  }
+}
+
+void gfx_imm_start(Imm* renderer) {
+  assert(renderer);
+
+  // Shader uniforms are applied lazily.
+  // TODO: In the event that gfx_activate_shader_program() activates uniforms
+  //  automatically for convenience, call an overload here that doesn't do so.
+  // gfx_activate_shader_program(renderer->shader);
+  gfx_llr_set_shader(renderer->llr, renderer->shader);
+}
+
+void gfx_imm_end(Imm* renderer) {
+  assert(renderer);
+
+  gfx_imm_flush(renderer);
+  // gfx_deactivate_shader_program(renderer->shader);
+  gfx_llr_set_shader(renderer->llr, 0);
+}
+
+void gfx_imm_draw_triangles(
+    Imm* renderer, const vec3 verts[], size_t num_triangles) {
+  assert(renderer);
+  assert(verts);
+  const size_t new_verts = num_triangles * 3;
+  assert(
+      renderer->num_triangle_verts + new_verts <
+      (GFX_IMM_MAX_NUM_TRIANGLES * 3));
+
+  memcpy(
+      renderer->triangle_verts + renderer->num_triangle_verts, verts,
+      new_verts * sizeof(vec3));
+
+  renderer->num_triangle_verts += new_verts;
+}
+
+void gfx_imm_draw_triangle(Imm* renderer, const vec3 verts[3]) {
+  gfx_imm_draw_triangles(renderer, verts, 1);
+}
+
+void gfx_imm_draw_aabb2(Imm* renderer, aabb2 box) {
+  assert(renderer);
+
+  // clang-format off
+  const vec3 verts[4] = {
+      vec3_make(box.min.x, box.min.y, 0),    // 3 ---- 2
+      vec3_make(box.max.x, box.min.y, 0),    // |      |
+      vec3_make(box.max.x, box.max.y, 0),    // |      |
+      vec3_make(box.min.x, box.max.y, 0)};   // 0 ---- 1
+  // clang-format on
+
+#define tri(i0, i1, i2) verts[i0], verts[i1], verts[i2]
+  const vec3 tris[6] = {tri(0, 1, 2), tri(0, 2, 3)};
+#undef tri
+
+  gfx_imm_draw_triangles(renderer, tris, 2);
+}
+
+void gfx_imm_draw_aabb3(Imm* renderer, aabb3 box) {
+  assert(renderer);
+
+  // clang-format off
+  const vec3 vertices[8] = {
+      vec3_make(box.min.x, box.min.y, box.max.z), //     7 ----- 6
+      vec3_make(box.max.x, box.min.y, box.max.z), //    /       /|
+      vec3_make(box.max.x, box.max.y, box.max.z), //   3 ----- 2 |
+      vec3_make(box.min.x, box.max.y, box.max.z), //   |       | |
+      vec3_make(box.min.x, box.min.y, box.min.z), //   | 4 ----- 5
+      vec3_make(box.max.x, box.min.y, box.min.z), //   |/      |/
+      vec3_make(box.max.x, box.max.y, box.min.z), //   0 ----- 1
+      vec3_make(box.min.x, box.max.y, box.min.z)};
+  // clang-format on
+
+  gfx_imm_draw_box3(renderer, vertices);
+}
+
+void gfx_imm_draw_box3(Imm* renderer, const vec3 vertices[8]) {
+  assert(renderer);
+  assert(vertices);
+
+  //     7 ----- 6
+  //    /       /|
+  //   3 ----- 2 |
+  //   |       | |
+  //   | 4 ----- 5
+  //   |/      |/
+  //   0 ----- 1
+
+#define tri(i0, i1, i2) vertices[i0], vertices[i1], vertices[i2]
+  const vec3 tris[36] = {
+      // Front.
+      tri(0, 1, 2), tri(0, 2, 3),
+      // Right.
+      tri(1, 5, 6), tri(1, 6, 2),
+      // Back.
+      tri(5, 4, 7), tri(5, 7, 6),
+      // Left.
+      tri(4, 0, 03), tri(4, 3, 7),
+      // Top.
+      tri(3, 2, 6), tri(3, 6, 7),
+      // Bottom.
+      tri(0, 4, 5), tri(0, 5, 1)};
+
+  gfx_imm_draw_triangles(renderer, tris, 12);
+}
+
+void gfx_imm_set_colour(Imm* renderer, vec4 colour) {
+  assert(renderer);
+  assert(renderer->shader);
+
+  gfx_imm_flush(renderer);
+
+  gfx_set_vec4_uniform(renderer->shader, "Colour", colour);
+}