add line drawing

CMakeLists.txt

@@ -85,8 +85,7 @@ endif()
 if(TWN_RENDERING_API MATCHES OPENGL_15)
         set(SYSTEM_SOURCE_FILES ${SYSTEM_SOURCE_FILES}
                 src/rendering/twn_gl_any_rendering.c
-                src/rendering/twn_gl_15_rendering.c
-                src/rendering/twn_gl_15_gpu_texture.c)
+                src/rendering/twn_gl_15_rendering.c)
 endif()
 
 set(TWN_THIRD_PARTY_SOURCE_FILES
@@ -142,7 +141,7 @@ set_target_properties(${TWN_TARGET} PROPERTIES
                                     C_STANDARD_REQUIRED ON
                                     C_EXTENSIONS ON) # extensions are required by stb_ds.h
 
-add_compile_definitions(${TWN_TARGET} $<$<BOOL:${TWN_FEATURE_PUSH_AUDIO}>:TWN_FEATURE_PUSH_AUDIO>)
+target_compile_definitions(${TWN_TARGET} PRIVATE $<$<BOOL:${TWN_FEATURE_PUSH_AUDIO}>:TWN_FEATURE_PUSH_AUDIO>)
 
 # precompile commonly used not-so-small headers
 target_precompile_headers(${TWN_TARGET} PRIVATE

include/twn_draw.h

@@ -42,6 +42,11 @@ TWN_API void draw_nine_slice(char const *texture,
                              float       border_thickness,  /* optional, default: 0 */
                              Color       color);            /* optional, default: all 255 */
 
+TWN_API void draw_line(Vec2 start,
+                       Vec2 finish,
+                       float thickness, /* optional, default: 1 */
+                       Color color);    /* optional, default: all 255 */
+
 /* pushes a textured 3d triangle onto the render queue */
 /* texture coordinates are in pixels */
 TWN_API void draw_triangle(char const *texture,

src/rendering/twn_draw.c

@@ -3,6 +3,7 @@
 #include "twn_engine_context_c.h"
 #include "twn_camera_c.h"
 #include "twn_types.h"
+#include "twn_util.h"
 #include "twn_vec.h"
 #include "twn_deferred_commands.h"
 
@@ -284,6 +285,20 @@ static void render_2d(void) {
                 break;
             }
 
+            /* TODO: batching */
+            case PRIMITIVE_2D_LINE: {
+                struct Render2DInvocation const invocation = {
+                    .primitive = current,
+                    .layer = layer,
+                };
+
+                if (current->line.color.a != 255)
+                    arrput(ghostly_invocations, invocation);
+                else
+                    arrput(opaque_invocations, invocation);
+                break;
+            }
+
             case PRIMITIVE_2D_TEXT: {
                 struct Render2DInvocation const invocation = {
                     .primitive = current,
@@ -320,6 +335,9 @@ static void render_2d(void) {
             case PRIMITIVE_2D_CIRCLE:
                 render_circle(&invocation.primitive->circle);
                 break;
+            case PRIMITIVE_2D_LINE:
+                render_line(&invocation.primitive->line);
+                break;
             case PRIMITIVE_2D_TEXT:
             default:
                 SDL_assert(false);
@@ -349,6 +367,9 @@ static void render_2d(void) {
             case PRIMITIVE_2D_TEXT:
                 render_text(&invocation.primitive->text);
                 break;
+            case PRIMITIVE_2D_LINE:
+                render_line(&invocation.primitive->line);
+                break;
             default:
                 SDL_assert(false);
         }
@@ -480,3 +501,28 @@ void issue_deferred_draw_commands(void) {
         }
     }
 }
+
+
+/* TODO: Support thickness */
+void draw_line(Vec2 start,
+               Vec2 finish,
+               float thickness,
+               Color color)
+{
+    if (fabsf(1.0f - thickness) >= 0.00001f)
+        log_warn("Thickness isn't yet implemented for line drawing (got %f)", (double)thickness);
+
+    LinePrimitive line = {
+        .start = start,
+        .finish = finish,
+        .thickness = thickness,
+        .color = color,
+    };
+
+    Primitive2D primitive = {
+        .type = PRIMITIVE_2D_LINE,
+        .line = line,
+    };
+
+    arrput(ctx.render_queue_2d, primitive);
+}

src/rendering/twn_draw_c.h

@@ -56,6 +56,13 @@ typedef struct SpritePrimitive {
     bool repeat;
 } SpritePrimitive;
 
+typedef struct LinePrimitive {
+    Vec2 start;
+    Vec2 finish;
+    float thickness;
+    Color color;
+} LinePrimitive;
+
 typedef struct RectPrimitive {
     Rect rect;
     Color color;
@@ -77,6 +84,7 @@ typedef struct TextPrimitive {
 
 typedef enum Primitive2DType {
     PRIMITIVE_2D_SPRITE,
+    PRIMITIVE_2D_LINE,
     PRIMITIVE_2D_RECT,
     PRIMITIVE_2D_CIRCLE,
     PRIMITIVE_2D_TEXT,
@@ -87,6 +95,7 @@ typedef struct Primitive2D {
 
     union {
         SpritePrimitive sprite;
+        LinePrimitive line;
         RectPrimitive rect;
         CirclePrimitive circle;
         TextPrimitive text;
@@ -288,6 +297,8 @@ VertexBuffer get_circle_element_buffer(void);
 
 void render_circle(const CirclePrimitive *circle);
 
+void render_line(const LinePrimitive *line);
+
 void render_rectangle(const RectPrimitive *rectangle);
 
 void finally_render_quads(Primitive2D const primitives[],

src/rendering/twn_gl_15_rendering.c

@@ -548,3 +548,13 @@ void finally_draw_command(DeferredCommandDraw command) {
     glBindBuffer(GL_ARRAY_BUFFER, 0);
     glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
 }
+
+void render_line(const LinePrimitive *line) {
+    finally_use_2d_pipeline();
+    glBegin(GL_LINES);
+        glColor4b(line->color.r, line->color.g, line->color.b, line->color.a);
+        glVertex2f(line->start.x, line->start.y);
+        glColor4b(line->color.r, line->color.g, line->color.b, line->color.a);
+        glVertex2f(line->finish.x, line->finish.y);
+    glEnd();
+}

src/rendering/twn_quads.c

@@ -170,6 +170,4 @@ void push_quad_payload_to_vertex_buffer_builder(struct QuadBatch batch,
 
         ((ElementIndexedQuadWithoutColorWithoutTexture *)builder->base)[index] = payload;
     }
-
-    SDL_assert(false);
 }