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fix circle rendering over new impl

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This commit is contained in:
veclav talica 2024-10-19 19:16:18 +03:00
parent 399b199266
commit a7b09b9f39
4 changed files with 24 additions and 12 deletions
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20
src/rendering/twn_circles.c
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@ -27,8 +27,10 @@ void create_circle_geometry(Vec2 position,
size_t num_vertices, size_t num_vertices,
Vec2 vertices[]) Vec2 vertices[])
{ {
SDL_assert(num_vertices <= CIRCLE_VERTICES_MAX);
/* the angle (in radians) to rotate by on each iteration */ /* the angle (in radians) to rotate by on each iteration */
float seg_rotation_angle = (360.0f / (float)num_vertices) * ((float)M_PI / 180); float seg_rotation_angle = (360.0f / (float)(num_vertices - 2)) * ((float)M_PI / 180);
vertices[0].x = (float)position.x; vertices[0].x = (float)position.x;
vertices[0].y = (float)position.y; vertices[0].y = (float)position.y;
@ -37,7 +39,7 @@ void create_circle_geometry(Vec2 position,
float start_x = 0.0f - radius; float start_x = 0.0f - radius;
float start_y = 0.0f; float start_y = 0.0f;
for (size_t i = 1; i < num_vertices + 1; ++i) { for (size_t i = 1; i < num_vertices - 1; ++i) {
float final_seg_rotation_angle = (float)i * seg_rotation_angle; float final_seg_rotation_angle = (float)i * seg_rotation_angle;
float c, s; float c, s;
@ -49,4 +51,18 @@ void create_circle_geometry(Vec2 position,
vertices[i].x += position.x; vertices[i].x += position.x;
vertices[i].y += position.y; vertices[i].y += position.y;
} }
// place a redundant vertex to make proper circling over shared element buffer
{
float final_seg_rotation_angle = (float)1 * seg_rotation_angle;
float c, s;
sincosf(final_seg_rotation_angle, &s, &c);
vertices[num_vertices - 1].x = c * start_x - s * start_y;
vertices[num_vertices - 1].y = c * start_y + s * start_x;
vertices[num_vertices - 1].x += position.x;
vertices[num_vertices - 1].y += position.y;
}
} }

1
src/rendering/twn_draw_c.h
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@ -23,7 +23,6 @@ extern Matrix4 camera_look_at_matrix;
#define QUAD_ELEMENT_BUFFER_LENGTH (65536 / 6) #define QUAD_ELEMENT_BUFFER_LENGTH (65536 / 6)
#define CIRCLE_VERTICES_MAX 2048 #define CIRCLE_VERTICES_MAX 2048
#define CIRCLE_ELEMENT_BUFFER_LENGTH (CIRCLE_VERTICES_MAX * 3)
typedef GLuint VertexBuffer; typedef GLuint VertexBuffer;

6
src/rendering/twn_gl_15_rendering.c
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@ -867,7 +867,7 @@ static void load_cubemap_side(const char *path, GLenum target) {
void render_circle(const CirclePrimitive *circle) { void render_circle(const CirclePrimitive *circle) {
static Vec2 vertices[CIRCLE_VERTICES_MAX]; static Vec2 vertices[CIRCLE_VERTICES_MAX];
int num_vertices = CIRCLE_VERTICES_MAX - 1; int num_vertices = MIN((int)circle->radius, CIRCLE_VERTICES_MAX);
create_circle_geometry(circle->position, create_circle_geometry(circle->position,
circle->radius, circle->radius,
@ -891,8 +891,8 @@ void render_circle(const CirclePrimitive *circle) {
command.color = circle->color; command.color = circle->color;
command.element_buffer = get_circle_element_buffer(); command.element_buffer = get_circle_element_buffer();
command.element_count = num_vertices * 3; command.element_count = (num_vertices - 2) * 3;
command.range_end = num_vertices * 3; command.range_end = (num_vertices - 2) * 3;
use_texture_mode(circle->color.a == 255 ? TEXTURE_MODE_OPAQUE : TEXTURE_MODE_GHOSTLY); use_texture_mode(circle->color.a == 255 ? TEXTURE_MODE_OPAQUE : TEXTURE_MODE_GHOSTLY);

9
src/rendering/twn_gl_any_rendering.c
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@ -65,9 +65,9 @@ VertexBuffer get_circle_element_buffer(void) {
if (buffer == 0) { if (buffer == 0) {
buffer = create_vertex_buffer(); buffer = create_vertex_buffer();
VertexBufferBuilder builder = build_vertex_buffer(buffer, sizeof (GLshort) * (CIRCLE_VERTICES_MAX - 1) * 3); VertexBufferBuilder builder = build_vertex_buffer(buffer, sizeof (GLshort) * (CIRCLE_VERTICES_MAX - 2) * 3);
for (size_t i = 1; i < CIRCLE_VERTICES_MAX; ++i) { for (size_t i = 1; i < CIRCLE_VERTICES_MAX - 1; ++i) {
/* first one is center point index, always zero */ /* first one is center point index, always zero */
GLshort indices[3]; GLshort indices[3];
@ -76,10 +76,7 @@ VertexBuffer get_circle_element_buffer(void) {
/* generated point index */ /* generated point index */
indices[1] = (GLshort)i; indices[1] = (GLshort)i;
size_t index = (i + 1) % (CIRCLE_VERTICES_MAX - 1); indices[2] = (GLshort)i + 1;
if (index == 0) /* don't use center for outer ring */
index = (CIRCLE_VERTICES_MAX - 1);
indices[2] = (GLshort)index;
push_to_vertex_buffer_builder(&builder, indices, sizeof indices); push_to_vertex_buffer_builder(&builder, indices, sizeof indices);
} }